Obesity and the Biological Clock: When Times Are out of Joint

May 10, 2012

Science Daily/Ludwig-Maximilians-Universitaet Muenchen (LMU)

Urgent appointments, tight work timetables and hectic social schedules structure modern life, and they very often clash with our intrinsic biological rhythms. The discrepancy results in so-called social jetlag, which can damage one's health. Among other effects, it can contribute to the development of obesity, as a new LMU study shows.

"Our surveys suggest that in Western societies two thirds of the population are burdened with a significant discrepancy between their internal time and the demands imposed by school and work schedules and leisure stress," says LMU chronobiologist Professor Till Roenneberg, who coined the term "social jetlag" to describe the phenomenon. If the rhythms dictated by our lifestyles are persistently out of phase with our biological clock, the risk of illness, such as high blood pressure and even cancer, rises.

Tired -- around the clock A team of researchers led by Roenneberg has now shown that social jetlag also contributes to another growing health problem, particularly in countries with a Western lifestyle -- obesity. Individuals who are overweight are at increased risk for serious metabolic diseases, such as diabetes. Many factors, in addition to excessive consumption of energy-rich foods, play a role in the development of obesity, and one of them is a lack of sleep. In persons who get too little sleep, the perception of hunger is perturbed, often leading to overeating.

And it is not just sleep duration that is important here. The LMU team has also found that social jetlag shows a significant association with increased body-mass index (BMI). The BMI, which is based on a quantitative relationship between weight and height, is used as a measure of body fat, and varies depending on age and sex.

Individuals with BMIs above the normal range are regarded as being overweight or obese. The results of the new study strongly indicate that a lifestyle that conflicts with our internal physiological rhythms can promote the development of obesity.

Moreover, it appears that the incidence of social jetlag is itself increasing, perhaps as a consequence of a general reduction in sleep duration."The ongoing debate on the usefulness of daylight-saving time (DST) should take note of our findings," remarks Roenneberg. "Just like conventional school and work schedules, DST disrupts our biological clock and subjects us to more social jetlag with all its consequences."

http://www.sciencedaily.com/releases/2012/05/120510132637.htm

New Research Explains How Proper Sleep is Important for Healthy Weight

May 7, 2012

Science Daily/Federation of American Societies for Experimental Biology

If you're counting calories to lose weight, that may be only part of the weight loss equation says a new research report published online in The FASEB Journal. In the report, French scientists show that impairments to a gene known to be responsible for our internal body clocks, called "Rev-Erb alpha," leads to excessive weight gain and related health problems. This provides new insights into the importance of proper alignment between the body's internal timing and natural environmental light cycles to prevent or limit excessive weight gain and the problems this weight gain causes.

According to Etienne Challet, Ph.D., a researcher involved in the work from the Department of Neurobiology of Rhythms at the Institute of Cellular and Integrative Neurosciences at the University of Strasbourg in Pascal, France,

"It is now clear that impairment of daily rhythms such as shift-work, exposure to artificial lighting, or jet-lag has multiple adverse effects on human health, every effort should be made to maintain or restore normal temporal organization and to avoid potentially disruptive behaviors such as nocturnal meals or light exposure at night."

To make this discovery, Challet and colleagues studied two groups of mice. One group was normal and the other group lacked the Rev-Erb alpha gene. In the mice lacking the Rev-Erb alpha gene, it was determined that they became obese and hyperglycaemic even if they ate the same quantity of food at the same time as normal mice.

Further scientific investigation showed that when the Rev-Erb alpha-deficient mice were compared to the normal mice, there was a major difference in the way Rev-Erb alpha-deficient mice metabolized the food they ate. The Rev-Erb alpha deficient mice created much more fat than the normal mice, and this occurred specifically during the feeding period. Additionally, the Rev-Erb-alpha deficient mice relied less on carbohydrate stores when at rest.

http://www.sciencedaily.com/releases/2012/05/120507113734.htm

Mid-afternoon slump? Why a sugar rush may not be the answer

Protein -- not sugar -- stimulates cells keeping us thin and awake, a new study suggests.

A new study has found that protein and not sugar activates the cells responsible for keeping us awake and burning calories. The research, published in the Nov. 17 issue of the scientific journal Neuron, has implications for understanding obesity and sleep disorders.

Wakefulness and energy expenditure rely on "orexin cells," which secrete a stimulant called orexin/hypocretin in the brain. Reduced activity in these unique cells results in narcolepsy and has been linked to weight gain.

Scientists at the University of Cambridge compared actions of different nutrients on orexin cells. They found that amino acids -- nutrients found in proteins such as egg whites -- stimulate orexin neurons much more than other nutrients.

"Sleep patterns, health, and body weight are intertwined. Shift work, as well as poor diet, can lead to obesity," said lead researcher Dr Denis Burdakov of the Department of Pharmacology and Institute of Metabolic Science. "Electrical impulses emitted by orexin cells stimulate wakefulness and tell the body to burn calories. We wondered whether dietary nutrients alter those impulses."

To explore this, the scientists highlighted the orexin cells (which are scarce and difficult to find) with genetically targeted fluorescence in mouse brains. They then introduced different nutrients, such as amino acid mixtures similar to egg whites, while tracking orexin cell impulses.

They discovered that amino acids stimulate orexin cells. Previous work by the group found that glucose blocks orexin cells (which was cited as a reason for after-meal sleepiness), and so the researchers also looked at interactions between sugar and protein. They found that amino acids stop glucose from blocking orexin cells (in other words, protein negated the effects of sugar on the cells).

These findings may shed light on previously unexplained observations showing that protein meals can make people feel less calm and more alert than carbohydrate meals.

"What is exciting is to have a rational way to 'tune' select brain cells to be more or less active by deciding what food to eat," Dr Burdakov said. "Not all brain cells are simply turned on by all nutrients, dietary composition is critical.

"To combat obesity and insomnia in today's society, we need more information on how diet affects sleep and appetite cells. For now, research suggests that if you have a choice between jam on toast, or egg whites on toast, go for the latter! Even though the two may contain the same number of calories, having a bit of protein will tell the body to burn more calories out of those consumed."

Mediterranean diet and exercise can reduce sleep apnea symptoms

November 28, 2011

Science Daily/European Lung Foundation

Eating a Mediterranean diet combined with physical activity can help to improve some of the symptoms of sleep apnea, according to new research. The study, which is published online in the European Respiratory Journal, looked at the impact a Mediterranean diet can have on obese people with sleep apnea, compared to those on a prudent diet.

Obstructive sleep apnea syndrome (OSAS) causes frequent pauses of breathing to occur during sleep, which disrupts a person's normal sleeping pattern. It is one of the most prevalent sleep-related breathing disorders with approximately 2-4% of the adult population experiencing the condition. This percentage increases up to 20-40% with obesity, and weight loss is often an essential part of the recommended treatment plan.

The researchers, from the University of Crete in Greece, examined 40 obese patients suffering from OSAS. Twenty patients were given a prudent diet to follow, while the other 20 followed a Mediterranean diet. Both groups were also encouraged to increase their physical activity, mainly involving walking for at least 30 minutes each day.

In both groups, the patients also received continuous positive airway pressure (CPAP) therapy which involves wearing a mask that generates an air stream, keeping the upper airway open during sleep.

The researchers monitored the patients during a sleep study, known as polysomnography. This involved monitoring several markers for OSAS, including electrical activity in the brain, eye movements and snoring. The patients were examined at the start of the study and again 6 months later.

The results showed that people following the Mediterranean diet had a reduced number of disturbances, known as apneas, during the rapid eye movement (REM) stage of sleep, which usually accounts for approximately 25% of total sleep during the night.

The findings also revealed that people following the Mediterranean diet also showed a greater adherence to the calorie restricted diet, an increase in physical activity and a greater decrease in abdominal fat.

The results of this small sample did show an improvement during one stage of sleep for people with sleep apnea, however it did not show an overall improvement in severity of the condition. The authors suggest that further studies in a larger sample are required to fully understand the benefits of this diet.

Christopher Papandreou, lead author for the research, said: "This is the first study examining the impact of the Mediterranean diet in combination with physical activity on OSAS via changes in the human body. Our results showed that the number of disturbances during REM sleep was reduced more in the Mediterranean diet group than the other group. Recent reports have related an increase in disturbances during REM sleep with the risk of developing significant systemic consequences like diabetes type II. However, its clinical significance remains unclear. Finally, more studies are needed to examine the effect of the above diet on this sleep-related breathing disorder taking into account its anti-inflammatory and antioxidant properties."

http://www.sciencedaily.com/releases/2011/11/111102093043.htm

Boosting mental performance with fish oil?

October 21, 2011

Science Daily/Northumbria University

A particular fish oil (omega-3) supplement has been shown to improve blood flow to the brain during mental activity and to impact on certain aspects of mental performance in young adults, according to new research.

In the first of two studies, currently available in the online edition of the British Journal of Nutrition, researchers found that overall, taking either of two different types of fish oil supplement for three months had no consistent impact on mental function in 18 -- 35-year-olds, however they did find evidence of reduced mental fatigue and faster reaction times. Contrary to popular belief, these results suggest that taking omega-3 or fish oil supplements may not have an immediate or measureable impact on mental performance in healthy young adults, possibly due to the fact that this population is already performing at its mental peak or that higher doses or longer than 12 weeks supplementation are required.

Interestingly, in the second of these studies it was found that taking DHA-rich fish oil over the same time period did increase blood flow to active areas of the brain during performance of similar mental tasks. The researchers claim these findings could have implications for mental function later on in life, as evidence suggests regularly eating oily fish or taking omega-3 supplements may prevent cognitive decline and dementia, and increased blood flow to the brain may be a mechanism by which this occurs.

As these results suggest benefits may be seen with longer term supplementation in older age groups, researchers now plan to investigate this in people between the ages of 50 and 70 to assess the impact of a fish oil supplement on their memory, mental performance and blood flow to the brain.

Lead researcher Dr Philippa Jackson said: "If we can pinpoint both the behavioural and brain blood flow effects of this fatty acid in older healthy people, then the benefits for those with mental degenerative conditions associated with normal aging could be that much greater."

Researchers are hoping to recruit more people to take part in the study to investigate the effects of DHA in older people.

They are keen to hear from individuals who are generally healthy, living in or near the Newcastle area who feel their memory is not as good as it used to be and who don't currently eat oily fish on a regular basis or take omega-3 supplements.

Participants will be asked to take a DHA-rich supplement for six months, for which they will receive £50 and a 12 month supply of the supplement.

http://www.sciencedaily.com/releases/2011/10/111021074640.htm

Early to bed and early to rise: it's keeping kids leaner

September 30, 2011

Science Daily/American Academy of Sleep Medicine

Researchers recording the bedtimes and wake times of 2,200 Australian youths found that the night owls were 1.5 times more likely to become obese than the early birds, twice as likely to be physically inactive and 2.9 times more likely to sit in front of the TV and computer or play video games for more hours than guidelines recommend.

A study in the Oct. 1 issue of the journal Sleep recorded the bedtimes and wake times of 2,200 Australian participants, ages 9 to 16, and compared their weights and uses of free time over four days. Children who went to bed late and got up late were 1.5 times more likely to become obese than those who went to bed early and got up early. Furthermore, late-nighters were almost twice as likely to be physically inactive and 2.9 times more likely to sit in front of the TV and computer or play video games for more hours than guidelines recommend.

"The children who went to bed late and woke up late, and the children who went to bed early and woke up early got virtually the same amount of sleep in total," said co-author Carol Maher, PhD, a postdoctoral fellow with the University of South Australia. "Scientists have realized in recent years that children who get less sleep tend to do worse on a variety of health outcomes, including the risk of being overweight and obese. Our study suggests that the timing of sleep is even more important."

Maher said mornings are more conducive to physical activity for young people than nights, which offer prime-time TV programming and social networking opportunities. This relationship between time of day and available activities might explain why more sedentary and screen-based behaviors were observed with later bedtimes, she said. At a time when research is showing that teenagers have a natural tendency to stay up late and wake late, the results of this study could stand as a warning.

"It is widely accepted that the sleep patterns of adolescents are fundamentally different from children and adults, and that it is normal for adolescents to stay up very late and sleep in late in the morning," Maher said. "Our findings show that this sleeping pattern is associated with unfavorable activity patterns and health outcomes, and that the adolescents who don't follow this sleep pattern do better."

Other findings from the University of South Australia study:

• ·      Early-bed/early-risers went to bed 70 to 90 minutes earlier, woke up 60 to 80 minutes earlier and accumulated 27 minutes more moderate to vigorous physical activity each day than late-risers.

• ·      Late-bed/late-risers watched TV, played video games or were online 48 minutes longer each day than early-bed/early risers, primarily between 7 p.m. and midnight.

• ·      Only 12 percent of late-bed/late-risers had an average of two hours or less screen time per day, which is recommended for children and teens by the Australian Department of Health and Aging. In comparison, 28 percent of early-bed/early risers met the recommendation for screen time.

• ·      On a broad scale, late-bed/late-risers replaced about 30 minutes of moderate to vigorous physical activity with 30 minutes of sedentary behavior each day, relative to the early-bed/early-rise group.

• ·      Body-mass index (BMI) scores were higher in late-risers than early-risers, and late-risers were more likely to be overweight or obese.

• ·      Late-bed/late-risers tended to have few siblings, live in major cities, come from lower household incomes and have a part-time job.

http://www.sciencedaily.com/releases/2011/09/110930052216.htm

Mindless eating: Losing weight without thinking

August 6, 2011

Science Daily/American Psychological Association

Dieters may not need as much willpower as they think, if they make simple changes in their surroundings that can result in eating healthier without a second thought, said a consumer psychologist at the American Psychological Association's 119th Annual Convention.

"Our homes are filled with hidden eating traps," said Brian Wansink, PhD, who presented his findings and strategies for a healthier lifestyle in a plenary address entitled "Modifying the Food Environment: From Mindless Eating to Mindlessly Eating Better."

"Most of us have too much chaos going on in our lives to consciously focus on every bite we eat, and then ask ourselves if we're full. The secret is to change your environment so it works for you rather than against you," Wansink said

Wansink identified several myths about eating behaviors as a way to explain why Americans, on average, have been getting fatter. "People don't think that something as simple as the size of a bowl would influence how much an informed person eats," he said.

However, several studies show exactly that, including Wansink's study of 168 moviegoers, who ate either fresh or stale popcorn from different size containers. People ate 45 percent more fresh popcorn from extra-large containers than large ones and the people who were eating stale popcorn ate 34 percent more from the extra-large buckets than people eating fresh popcorn, according to the study.

They just don't realize they're doing it," said Wansink. This strategy also applies to what we drink. His research found that people pour about 37 percent more liquid in short, wide glasses than in tall, skinny ones of the same volume.

Even a kid's cereal bowl can be a trap, according to Wansink. One study showed children of different weights who were given a 16 ounce bowl were more likely to serve themselves twice as much cereal than children given an 8 ounce bowl.

Another myth, according to Wansink, is that people know when they are full and stop before they overeat. His Food and Brand Lab at Cornell University tested this by designing a "bottomless bowl." They brought in 60 people for a free lunch and gave 22 ounce bowls of soup to half, while the other half unknowingly got 22 ounce bowls that were pressure-fed under the table and slowly refilled. The results: people with bottomless bowls ate 73 percent more than those with normal bowls, yet when asked, they didn't realize they had eaten more. "The lesson is, don't rely on your stomach to tell you when you're full. It can lie," Wansink said.

Simply being aware of such findings can help people make healthier choices, especially those who are already trying to eat healthier foods, according to Wansink. One of his studies showed that people lost up to two pounds a month after making several simple changes in their environment, including:

• ·      eating off salad plates instead of large dinner plates.
• ·      keeping unhealthy foods out of immediate line of sight and moving healthier foods to eye-level in the cupboard and refrigerator.
• ·      eating in the kitchen or dining room, not in front of the television.

"These simple strategies are far more likely to succeed than willpower alone. It's easier to change your environment than to change your mind," Wansink concluded.

http://www.sciencedaily.com/releases/2011/08/110805163541.htm

Think healthy, eat healthy: Scientists show link between attention and self-control

August 10, 2011

Science Daily/California Institute of Technology

You're trying to decide what to eat for dinner. Should it be the chicken and broccoli? The super-sized fast-food burger? Skip it entirely and just get some Rocky Road?

Making that choice, it turns out, is a complex neurological exercise. But, according to researchers from the California Institute of Technology (Caltech), it's one that can be influenced by a simple shifting of attention toward the healthy side of life. And that shift may provide strategies to help us all make healthier choices -- not just in terms of the foods we eat, but in other areas, like whether or not we pick up a cigarette.

Their research is described in a paper published in the July 27 issue of the Journal of Neuroscience.

When you decide what to eat, not only does your brain need to figure out how it feels about a food's taste versus its health benefits versus its size or even its packaging, but it needs to decide the importance of each of those attributes relative to the others. And it needs to do all of this more-or-less instantaneously.

Antonio Rangel, professor of economics and neuroscience at Caltech, has been studying this value-deriving and decision-making process for years now. Along with Todd Hare -- a former postdoc at Caltech who is now an assistant professor of neuroeconomics at the University of Zurich in Switzerland -- he published a paper in Science in 2009 describing differences in the brains of people who are better at exercising self-control than others. What they found was that while everyone uses the same area of the brain -- the ventral medial prefrontal cortex, or vmPFC -- to make value-laden decisions like what to munch on, there's a second brain area -- the dorsolateral prefrontal cortex, or dlPFC -- that seems to come to life when a person is using self-control during the decision-making process.

In other words, when the dlPFC is active, it allows the vmPFC to take into account health benefits as well as taste when it assigns a value to a particular food.

The new study goes a step further, showing that there seem to be ways to help kickstart the dlPFC through the use of what Hare calls "external cues" that allow us to exhibit more self-control than we might have otherwise.

The researchers came to their conclusions based on data from a brain-imaging experiment conducted with 33 adult volunteers, none of whom were following a specific diet or trying to lose weight for any reason. Each of the volunteers was shown 180 different food items -- from chips and candy bars to apples and broccoli -- through a set of video goggles while in a functional magnetic resonance imaging (fMRI) machine.

The hungry subjects -- they were asked to fast for at least three hours prior to the experiment -- were given up to three seconds to respond to each picture with a decision about whether or not they'd want to eat the food shown after the experiment was over. They could either give the food a "strong no," a "no," a "yes," or a "strong yes." Once all of the images had been flipped through, a single food image was chosen at random; if the volunteer had said "yes" or "strong yes" to the idea of eating that food, he or she was served that item.

"Because only one random trial was selected to 'count,'" says Rangel, "the optimal strategy for subjects is to treat each decision as if it were the only one."

Simple, right? But here's the catch: before every 10 food choices, an instruction would come on the screen for five seconds telling the subjects either to "consider the healthiness," "consider the tastiness," or "make decisions naturally." This meant that of the 180 decisions, the subjects made 60 in each of the three "instruction conditions."

What this was meant to do, Rangel explains, is shift the subject's attention during the experiment and, potentially, shift the way in which they made decisions.

Afterward -- outside the scanner -- the subjects were asked to rate the same foods on both a tastiness scale (very untasty, untasty, tasty, very tasty) and a healthiness scale (very unhealthy, unhealthy, healthy, very healthy). That way, the researchers were able to associate the choices the subjects made during the brain scan with their stated perceptions of those foods' attributes -- showing that a subject who chose broccoli during the "consider the healthiness" portion of the test might think of it nonetheless as untasty.

The researchers then classified the foods for each subject based on that subject's ratings: unhealthy-untasty, healthy-untasty, unhealthy-tasty, and healthy-tasty. Unsurprisingly, people chose healthy-tasty foods no matter where their attention had been directed.

Things got interesting when the researchers looked at the other three categories, however. Among their findings:

• When thinking about healthiness, subjects were less likely to eat unhealthy foods, whether or not they deemed them to be tasty, and more likely to eat healthy-untasty foods.
• Being asked to think about healthiness led subjects to say "no" to foods more often than they did when asked to make decisions naturally.
• There were no real differences between the choices made during the "consider the tastiness" and "make decisions naturally" portions of the experiment.

When the researchers turned to the fMRI results, they found that the vmPFC was, as predicted, "more responsive to the healthiness of food in the presence of health cues," says Rangel. And, as they'd seen previously, the robustness of that response was due to the influence of the dlPFC -- that bastion of self-control -- which was much quieter when the study's subjects were thinking about taste or their own personal choice than when they were asked to throw healthiness into the equation.

"This increased influence of the health signals on the vmPFC results in an overall value for the food that is based more on its health properties than is the case when the subject's attention is not focused on healthiness," says Hare.

These results are most likely not limited just to choices about food, Hare says. "Our findings are also relevant to the current changes to cigarette warnings many governments have started to make," he notes. "These changes include adding graphical images of the health risks of smoking. It remains to be seen whether these images will be more effective in drawing attention to the unhealthiness of smoking than the text warnings. If the graphical warnings do increase attention to health, then our results suggest that they could decrease the desire to smoke."

Jonathan Malmaud, a former research assistant at Caltech who is now a graduate student at MIT, was also an author on the Journal of Neuroscience paper, "Focusing attention on the health aspects of foods changes value signals in the vmPFC and improves dietary choice." The scientists' work was funded by a grant from the National Science Foundation.

http://www.sciencedaily.com/releases/2011/07/110727122815.htm

'Love your body' to lose weight

July 18, 2011

Science Daily/BioMed Central Limited

Almost a quarter of men and women in England and over a third of adults in America are obese. Obesity increases the risk of diabetes and heart disease and can significantly shorten a person's life expectancy. New research published by BioMed Central's open access journal International Journal of Behavioral Nutrition and Physical Activity shows that improving body image can enhance the effectiveness of weight loss programs based on diet and exercise.

Researchers from the Technical University of Lisbon and Bangor University enrolled overweight and obese women on a year-long weight loss program. Half the women were given general health information about good nutrition, stress management, and the importance of looking after yourself. The other half attended 30 weekly group sessions (the intervention plan) where issues such as exercise, emotional eating, improving body image and the recognition of, and how to overcome, personal barriers to weight loss and lapses from the diet were discussed.

On the behavioral intervention plan women found that the way they thought about their body improved and that concerns about body shape and size were reduced. Compared to the control group they were better able to self-regulate their eating and they lost much more weight, losing on average 7% of their starting weight compared to less than 2% for the control group.

Dr. Teixeira from Technical University of Lisbon, who led the research, said, "Body image problems are very common amongst overweight and obese people, often leading to comfort eating and more rigid eating patterns, and are obstacles to losing weight.

Our results showed a strong correlation between improvements in body image, especially in reducing anxiety about other peoples' opinions, and positive changes in eating behavior. From this we believe that learning to relate to your body in healthier ways is an important aspect of maintaining weight loss and should be addressed in every weight control program."

http://www.sciencedaily.com/releases/2011/07/110717204913.htm

Moderate Sleep and Less Stress May Help with Weight Loss

May 26, 2011

Science Daily/Kaiser Permanente

If you want to increase your chances of losing weight, reduce your stress level and get adequate sleep. A new Kaiser Permanente study found that people trying to lose at least 10 pounds were more likely to reach that goal if they had lower stress levels and slept more than six hours but not more than eight hours a night.

"This study suggests that when people are trying to lose weight, they should try to get the right amount of sleep and reduce their stress," said lead author Charles Elder, MD, MPH, an investigator with the Kaiser Permanente Center for Health Research in Portland, Ore., who also leads Integrative Medicine at Kaiser Permanente Northwest.

"Some people may just need to cut back on their schedules and get to bed earlier. Others may find that exercise can reduce stress and help them sleep. For some people, mind/body techniques such as meditation also might be helpful."

People with the lowest stress levels who also got more than six hours, but not more than eight hours, of sleep were most likely to lose at least 10 pounds. In fact, nearly three-quarters of this group moved on to the second phase of the trial, and were twice as likely to be successful as those who reported the highest stress levels and got six or fewer hours of sleep per night.

http://www.sciencedaily.com/releases/2011/03/110329095440.htm

Maternal Obesity Puts Infants at Risk of Iron Deficiency

May 1, 2011

Science Daily/American Academy of Pediatrics

Babies born to obese mothers are at risk for iron deficiency, which could affect infant brain development, according to a study presented on April 30 at the Pediatric Academic Societies (PAS) annual meeting in Denver.

In nonpregnant adults, obesity-related inflammation hinders the transport of iron through the intestine, increasing the risk of iron deficiency anemia. When a woman is pregnant, iron is transferred through the intestine to the placenta, but it is not known how maternal obesity affects newborn iron status. Fetal iron status is important because 50 percent of the iron needed for infant growth is obtained before birth.

In this study, researchers studied 281 mother/newborn pairs. The women's body mass index was calculated before delivery, and a score of 30 or above was defined as obese. Investigators also determined infants' iron level by analyzing umbilical cord blood.

Results showed evidence of impaired iron status in newborns of women who were obese.

"These findings are important because iron deficiency in infancy is associated with impaired brain development, and we should understand all risk factors for iron deficiency in infancy," said Pamela J. Kling, MD, FAAP, principal investigator and associate professor of pediatrics/neonatology at the University of Wisconsin-Madison.

The researchers are investigating why obesity during pregnancy is a risk factor for poorer iron status at birth, Dr. Kling said.

"In nonpregnant adults, obesity has been linked to poorer dietary iron absorption and to diabetes, so both factors may contribute," she said. "Additionally, the link may be due to larger fetuses, because obesity during pregnancy results in larger fetuses, and iron needs are proportional to fetal size."

The study results also have important implications because the prevalence of obesity in women of childbearing age is increasing.

http://www.sciencedaily.com/releases/2011/04/110430133125.htm

Sleep Loss Limits Fat Loss

October 5, 2010

Science Daily/University of Chicago Medical Center

Cutting back on sleep reduces the benefits of dieting, according to a study published October 5, 2010, in the Annals of Internal Medicine.

When dieters in the study got a full night's sleep, they lost the same amount of weight as when they slept less. When dieters got adequate sleep, however, more than half of the weight they lost was fat. When they cut back on their sleep, only one-fourth of their weight loss came from fat.

They also felt hungrier. When sleep was restricted, dieters produced higher levels of ghrelin, a hormone that triggers hunger and reduces energy expenditure.

"If your goal is to lose fat, skipping sleep is like poking sticks in your bicycle wheels," said study director Plamen Penev, MD, PhD, assistant professor of medicine at the University of Chicago. "Cutting back on sleep, a behavior that is ubiquitous in modern society, appears to compromise efforts to lose fat through dieting. In our study it reduced fat loss by 55 percent."

Getting adequate sleep also helped control the dieters' hunger. Average levels of ghrelin did not change when dieters spent 8.5 hours in bed. When they spent 5.5 hours in bed, their ghrelin levels rose over two weeks from 75 ng/L to 84 ng/L.

Higher ghrelin levels have been shown to "reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase hepatic glucose production to support the availability of fuel to glucose dependent tissues," the authors note. "In our experiment, sleep restriction was accompanied by a similar pattern of increased hunger and … reduced oxidation of fat."

The tightly controlled circumstances of this study may actually have masked some of sleep's benefits for dieters, suggested Penev. Study subjects did not have access to extra calories. This may have helped dieters to "stick with their lower-calorie meal plans despite increased hunger in the presence of sleep restriction," he said.

The message for people trying to lose weight is clear, Penev said. "For the first time, we have evidence that the amount of sleep makes a big difference on the results of dietary interventions. One should not ignore the way they sleep when going on a diet. Obtaining adequate sleep may enhance the beneficial effects of a diet. Not getting enough sleep could defeat the desired effects."

http://www.sciencedaily.com/releases/2010/10/101004211637.htm

Disrupted Circadian Rhythm May Cause Triglycerides to Rise

August 4, 2010

Science Daily/Cell Press

When the circadian rhythm gets thrown off, it could come with an unexpected side effect: high triglycerides. The discovery, based on studies in mice with a "broken clock," helps to explain the normal rise and fall in triglycerides, which happens at about the same time each day, according to researchers who report their findings in the August issue of Cell Metabolism, a Cell Press publication.

"We show that the normal up and down [of triglycerides] is lost in clock mutants," said M. Mahmood Hussain of SUNY Downstate Medical Center. "They have high triglycerides all the time." An elevated triglyceride level is a risk factor for atherosclerosis and heart disease.

Several biological, physiological, and behavioral activities show a characteristic recurrence with 24-hour intervals attuned to sunrise and sunset, the researchers explained. That circadian rhythm is driven by the interaction of so-called clock genes.

In normal mice, plasma triglycerides double or triple over the course of the day, reaching their lowest point at night when the nocturnal animals eat and are most active, the new report shows. In clock mutants, triglyceride levels don't change; rather, they stay high all the time.

The researchers delved further into the mechanism linking the animal's internal clocks to triglycerides. They found that a core component of the circadian circuitry -- a protein known as CLOCK -- controls levels of another protein (called microsomal triglyceride transfer protein, or MTP) that helps to ferry triglycerides through the bloodstream. That control takes place via yet another transcription factor.

"Metabolic syndrome and obesity are major metabolic disorders characterized by high plasma lipid concentrations," the researchers conclude. "Plasma lipids are tightly controlled by mechanisms regulating their production and clearance. Here, we show that light-entrained mechanisms involving clock genes also play a role in regulating plasma triglyceride."

If the findings in mice can be extrapolated to humans, it suggests that the effects of drugs designed to lower triglyceride levels by acting on MTP might depend on when they are taken each day, the researchers said.

"The dose needed may vary depending on the time of day," Hussain said. "Now we can start to think about [the role of] drug timing in controlling disease states."

The findings also suggest that activities that disrupt the circadian rhythm -- staying up until 2:00 a.m. or traveling overseas -- might come with real consequences for lipid metabolism, he added.

http://www.sciencedaily.com/releases/2010/08/100803132736.htm

Preterm Births Higher Among Overweight and Obese Mothers

July 20, 2010

Science Daily/BMJ-British Medical Journal

Overweight and obese women are at greater risk of giving birth to a preterm baby compared with normal weight women, finds a study published online in the British Medical Journal.

Overweight and obesity is now the most common pregnancy complication in many developed countries and also some developing countries. For example, in the United Kingdom, 33% of pregnant women are overweight or obese. In India, 26% of pregnant women are overweight and a further 8% are obese, while in China, 16% are overweight or obese.

They found that the overall risk of preterm birth before 37 weeks was not significantly different among overweight or obese women compared with normal weight women.

However, there was a 30% increased risk of induced preterm birth before 37 weeks among overweight or obese women after accounting for publication bias, which is the tendency for studies to be published only if their results are positive. The heavier the woman, the higher the risk of induced preterm birth before 37 weeks, with very obese women at 70% greater risk than normal weight women.

Overweight or obese women also had a higher risk of early preterm birth (before 32 or 33 weeks). Again, the heavier the woman, the higher the risk of early preterm birth, with very obese women at 82% greater risk than normal weight women.

Although overweight or obese women had a lower risk of delivering a low birth weight baby than normal weight women, especially in developing countries, this effect disappeared after publication bias was taken into account. "Clinicians need to be aware that maternal overweight or obesity is not protective against low birth weight and consider surveillance when indicated," warn the authors.

"Ideally, overweight or obese women should have pregnancy counselling so that they are informed of their perinatal risks and can try to optimise their weight before pregnancy," they conclude.

http://www.sciencedaily.com/releases/2010/07/100720212929.htm

That Late-Night Snack: Worse Than You Think

September 7, 2009

Science Daily/Northwestern University

Eat less, exercise more. Now there is new evidence to support adding another "must" to the weight-loss mantra: eat at the right time of day.

A Northwestern University study has found that eating at irregular times -- the equivalent of the middle of the night for humans, when the body wants to sleep -- influences weight gain. The regulation of energy by the body's circadian rhythms may play a significant role. The study is the first causal evidence linking meal timing and increased weight gain.

"One of our research interests is shift workers, who tend to be overweight," said lead author Deanna M. Arble, a doctoral student in Turek's lab. "Their schedules force them to eat at times that conflict with their natural body rhythms. This was one piece of evidence that got us thinking -- eating at the wrong time of day might be contributing to weight gain. So we started our investigation with this experiment."

Simply modifying the time of feeding alone can greatly affect body weight, the researchers found. Mice that were fed a high-fat diet during normal sleeping hours gained significantly more weight (a 48 percent weight increase over their baseline) than mice eating the same type and amount of food during naturally wakeful hours (a 20 percent increase over their baseline). There was no statistical difference between the two groups regarding caloric intake or the amount of activity.

http://www.sciencedaily.com/releases/2009/09/090903110800.htm

Another Reason to Avoid High-Fat Diet: It Can Disrupt Our Biological Clock

December 31, 2008

Science Daily/Hebrew University of Jerusalem

Indulgence in a high-fat diet can not only lead to overweight because of excessive calorie intake, but also can affect the balance of circadian rhythms – everyone’s 24-hour biological clock, Hebrew University of Jerusalem researchers have shown.

The biological clock regulates the expression and/or activity of enzymes and hormones involved in metabolism, and disturbance of the clock can lead to such phenomena as hormone imbalance, obesity, psychological and sleep disorders and cancer.

While light is the strongest factor affecting the circadian clock, Dr. Oren Froy and his colleagues of the Institute of Biochemistry, Food Science and Nutrition at the Hebrew University’s Robert H. Smith Faculty of Agriculture, Food and Environment in Rehovot, have demonstrated in their experiments with laboratory mice that there is a cause-and-effect relation between diet and biological clock imbalance.

To examine this thesis, Froy and his colleagues, Ph.D. student Maayan Barnea and Zecharia Madar, the Karl Bach Professor of Agricultural Biochemistry, tested whether the clock controls the adiponectin signaling pathway in the liver and, if so, how fasting and a high-fat diet affect this control. Adiponectin is secreted from differentiated adipocytes (fat tissue) and is involved in glucose and lipid metabolism. It increases fatty acid oxidation and promotes insulin sensitivity, two highly important factors in maintaining proper metabolism.

The researchers fed mice either a low-fat or a high-fat diet, followed by a fasting day, then measured components of the adiponectin metabolic pathway at various levels of activity. In mice on the low-fat diet, the adiponectin signaling pathway components exhibited normal circadian rhythmicity. Fasting resulted in a phase advance. The high-fat diet resulted in a phase delay. Fasting raised and the high-fat diet reduced adenosine monophosphate-activated protein kinase (AMPK) levels. This protein is involved in fatty acid metabolism, which could be disrupted by the lower levels.

In an article soon to be published by the journal Endocrinology, the researchers suggest that this high-fat diet could contribute to obesity, not only through its high caloric content, but also by disrupting the phases and daily rhythm of clock genes. They contend also that high fat-induced changes in the clock and the adiponectin signaling pathway may help explain the disruption of other clock-controlled systems associated with metabolic disorders, such as blood pressure levels and the sleep/wake cycle.

http://www.sciencedaily.com/releases/2008/12/081228191054.htm

Fat Intake Negatively Influences the Sleep Pattern in Healthy Adults

June 12, 2008

Science Daily/American Academy of Sleep Medicine

Total fat intake and dinner fat intake seem to influence negatively the sleep pattern in healthy adults, according to a research abstract that will be presented on June 10 at SLEEP 2008, the 22nd Annual Meeting of the Associated Professional Sleep Societies (APSS).

"We showed that an increased fat intake was associated with a lower percentage of REM sleep, a higher arousal index and apnea-hypopnea index, and a lower sleep efficiency," said Crispim. "These results showed that total fat intake and dinner fat intake seem to influence negatively the sleep pattern. However, researches in the nutrition and sleep area should be carried out to better understand these associations."

"Previous studies have demonstrated that circadian distribution of food intake is capable of modifying endocrine and metabolic patterns during sleep. However, studies of the influence of food intake distribution on sleep pattern are scarce. This study, which analyzed the influence of energy intake on the sleep patterns in healthy subjects, concluded that total energy intake and late-night snack energy intake may increase sleep fragmentation in healthy subjects, which might increase the effects of sleep restriction on nutritional and metabolic balance. New studies on this area are needed to better understand theses associations," said Zalcman.

http://www.sciencedaily.com/releases/2008/06/080610072056.htm

Sleep Problems Linked to Obesity, Lower Quality of Life in School-Aged Children

June 10, 2008

Science Daily/American Academy of Sleep Medicine

A research abstract that will be presented on June 10 at SLEEP 2008, the 22nd Annual Meeting of the Associated Professional Sleep Societies (APSS), finds an increased prevalence of sleep problems among school-aged children who are obese and an association between increased weight and lower quality of life.

According to the results, children who were obese had poorer scores for sleep onset delay, sleep-disordered breathing, sleep duration, and daytime sleepiness, compared to children who were overweight or healthy weight. Weight category was a significant predictor of parent-reported physical, psychosocial, and total quality of life scores, as well as child-reported physical functioning scores. Weight category and sleep problem category were significant predictors of child-reported psychosocial and total quality of life scores.

While an increasing number of adults are considered obese, the number of obese children is also on the rise. Obesity can increase children's risk for developing obstructive sleep apnea (OSA), a sleep-related breathing disorder that causes your body to stop breathing during sleep. OSA, which can disturb your sleep numerous times on any given night, can result in daytime sleepiness, as well as an increased risk of stroke, diabetes and heart disease. OSA is a serious sleep disorder that can be harmful, or even fatal, if left untreated.

It is recommended that school-aged children get between 10-11 hours of nightly sleep and children in pre-school between 11-13 hours.

http://www.sciencedaily.com/releases/2008/06/080610072004.htm

Children of older mothers do better

The benefits associated with being born in a later year outweigh the biological risks associated with being born to an older mother

April 12, 2016

Science Daily/Max-Planck-Gesellschaft

The benefits associated with being born in a later year outweigh the biological risks associated with being born to an older mother.

Most previous research suggests that the older women are when they give birth, the greater the health risks are for their children. Childbearing at older ages is understood to increase the risk of negative pregnancy outcomes such as Down syndrome, as well as increase the risk that the children will develop Alzheimer's disease, hypertension, and diabetes later in life.

However, despite the risks associated with delaying childbearing, children may also benefit from mothers delaying childbearing to older ages. These are the findings from a new study conducted by Mikko Myrskylä, the director of the Max Planck Institute for Demographic Research (MPIDR),) and his colleague Kieron Barclay at the London School of Economics, that has been published today in Population and Development Review.

Both public health and social conditions have been improving over time in many countries. Previous research on the relationship between maternal age and child outcomes has ignored the importance of these macro-level environmental changes over time. From the perspective of any individual parent, delaying childbearing means having a child with a later birth year. For example, a ten-year difference in maternal age is accompanied by a decade of changes to social and environmental conditions. Taking this perspective, this new MPIDR-study shows that when women delay childbearing to older ages their children are healthier, taller, and more highly educated. It shows that despite the risks associated with childbearing at older ages, which are attributable to aging of the reproductive system, these risks are either counterbalanced, or outweighed, by the positive changes to the environment in the period during which the mother delayed her childbearing.

For example, a woman born in 1950 who had a child at the age of 20 would have given birth in 1970. If that same woman had a child at 40, she would have given birth in 1990. "Those twenty years make a huge difference," explains Mikko Myrskylä. A child born in 1990, for example, had a much higher probability of going to a college or university than somebody born 20 years earlier.

Barclay and Myrskylä used data from over 1.5 million Swedish men and women born between 1960 and 1991 to examine the relationship between maternal age at the time of birth, and height, physical fitness, grades in high school, and educational attainment of the children. Physical fitness and height are good proxies for overall health, and educational attainment is a key determinant of occupational achievement and lifetime opportunities.

They found that when mothers delayed childbearing to older ages, even as old as 40 or older, they had children who were taller, had better grades in high school, and were more likely to go to university. For example, comparing two siblings born to the same mother decades apart, on average the child born when the mother was in her early 40s spends more than a year longer in the educational system than his or her sibling born when the mother was in her early 20s.

In their statistical analyses, Barclay and Myrskylä compared siblings who share the same biological mother and father. Siblings share 50% of their genes, and also grow up in the same household environment with the same parents. "By comparing siblings who grew up in the same family it was possible for us to pinpoint the importance of maternal age at the time of birth independent of the influence of other factors that might bias the results" said Kieron Barclay.

"The benefits associated with being born in a later year outweigh the individual risk factors arising from being born to an older mother. We need to develop a different perspective on advanced maternal age. Expectant parents are typically well aware of the risks associated with late pregnancy, but they are less aware of the positive effects" said Myrskylä.

https://www.sciencedaily.com/releases/2016/04/160412104810.htm

Mommy and me: Study shows how affectionate mothering can combat the effects of maternal depression

February 11, 2016

Science Daily/University of Utah

Certain parenting strategies can combat the negative impacts of maternal depression on an infant, suggests the first study of its kind. The work sought to investigate how a depressed mother's neuroendocrine response to stress can program the infant's hypothalamic-pituitary-adrenal axis, a set of signals and relationships between the hypothalamus, the pituitary gland and the adrenals. The hypothalamic-pituitary-adrenal axis is responsible for creating cortisol, a hormone released in response to stress.

Poverty, lack of education and exposure to violence can undeniably impact a child's life trajectory significantly. But how can a mother's exposure and potentially depressive reactions to these stressors impact a child before his/her life even begins? A depressed mother's response to stress can pass through the placenta to negatively impact the fetus in ways that manifest after birth such as birth weight, brain development and increased susceptibility to various ailments.

The first study of its kind, "The contributions of maternal sensitivity and maternal depressive symptoms to epigenetic processes and neuroendocrine functioning," led by University of Utah assistant professor Elisabeth Conradt in the Department of Psychology, found that certain parenting strategies can combat the negative impacts of maternal depression on an infant. The findings were published in Child Development.

The mechanics of stress relief

Conradt's study sought to investigate how a depressed mother's neuroendocrine response to stress can program the infant's hypothalamic-pituitary-adrenal axis, a set of signals and relationships between the hypothalamus, the pituitary gland and the adrenals. The hypothalamic-pituitary-adrenal axis is responsible for creating cortisol, a hormone released in response to stress.

Existing research with animal models suggest that this programming can occur after birth through epigenetic mechanisms, or changes in gene expression that do not change the genes themselves and can be passed between generations, through the quality of the mother's caregiving.

"We were curious about whether maternal behavior could "buffer" the child against the effects of maternal depression, and if this buffering could be observed at the level of the infant's epigenome," said Conradt.

Inspired by these animal studies, Conradt's team sought to determine whether, and how, the quality of the postnatal environment, specifically maternal sensitivity, is related to DNA methylation of genes involved in hypothalamic-pituitary-adrenal axis functioning and infants' neuroendocrine functioning in humans.

DNA methylation is when a methyl group is added to an individual cytosine (one of the four main building blocks of DNA and RNA). When the methyl group is added to a gene promoter, the region of DNA that initiates gene expression, this leads to reduced gene activity.

Prior research indicates that being depressed while pregnant and exposure to childhood abuse is related to increased DNA methylation, and subsequently reduced gene activity, of key stress-related genes including the glucoroticoid receptor gene (NR3C1) and 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2).

Increased methylation of 11β-HSD2 leads to greater exposure of the fetus to maternal cortisol while increased methylation of NR3C1 results in fewer glucocorticoid receptors to which cortisol can bind and therefore greater levels of cortisol in the blood.

Conscious detachment: Ignoring babies to induce stress

To investigate whether DNA methylation of NR3C1 and 11β-HSD2 was related to maternal depressive symptoms and/or maternal sensitivity, Conradt and her team worked with 128 infants of women with self-reported symptoms of depression and obtained DNA (to test for methylation) from the infants through cheek swabs and cortisol levels from their saliva.

The infants each participated in three two-minute face-to-face play episodes with their mothers. The first play episode required normal play between mother and infant, the second episode required that the mothers be unresponsive to their infants and the third episode was a reunion episode where mothers were allowed to interact again.

Maternal sensitivity, recorded every 30 seconds, was assessed using four scales. First, maternal acceptance: Willingness and ability of the mother to follow her infant's lead. Second, demandingness: the degree to which the mother required her infant to behave a certain way. Third, responsiveness: Both the mother's awareness of her infant's signals and her response to them, regardless of the appropriateness of response. Fourth, appropriate touch: The mother's ability to touch her infant in a gentle and affectionate manner as opposed to a more intrusive manner.

The researchers took a pre-stress cortisol sample from each infant prior to entering the lab and two post-stress samples after the unresponsive play episode and after the reunion play episode. A cheek swab for DNA was taken after the second play episode.

When put to the test, sensitivity beat stress

The research team found that greater levels of maternal sensitivity were related to lower levels of cortisol. While there were no differences in DNA methylation among infants whose mothers scored high on sensitivity, infants whose mothers were both less sensitive and had high depressive symptoms had higher levels of methylation and more cortisol.

Furthermore, mothers with depressive symptoms who were more responsive and engaged in more appropriate touch during face-to-face play had infants with less DNA methylation compared to mothers with depressive symptoms who were also insensitive.

Having a sensitive caregiver, therefore, appears to buffer infants from the exposure of the mother's depressive symptoms. Infants aren't aware of whether their caregivers are depressed or not; they are only aware of how they're treated. This study is the first to demonstrate that certain forms of maternal caregiving can have such an effect.

"Many mothers struggle with depression but interact quite sensitively with their infants. In these instances, the mother may be "turning on" certain genes that we think allow infants to manage stress in adaptive ways," Conradt summarized.

Conradt and her team are currently replicating and extending this study with first-time pregnant women in Utah to better understand whether parenting can buffer the infant to the effects of prenatal exposure to stress and depression.

"We are excited about the possibility that this research may lead to specific ways one can effectively intervene with pregnant women at risk for postpartum depression."

https://www.sciencedaily.com/releases/2016/02/160211185003.htm