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