That late-night snack: Worse than you think

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.

"How or why a person gains weight is very complicated, but it clearly is not just calories in and calories out," said Fred Turek, professor of neurobiology and physiology in the Weinberg College of Arts and Sciences and director of the Center for Sleep and Circadian Biology. "We think some factors are under circadian control. Better timing of meals, which would require a change in behavior, could be a critical element in slowing the ever-increasing incidence of obesity."

The findings could have implications for developing strategies to combat obesity in humans, as the United States and the world battle what has been called an "obesity epidemic." More than 300 million adults worldwide are obese, including more than a third of American adults.

Details of the obesity study, which was led by Turek, will be published online Sept. 3 by the journal Obesity.

"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.

Over a period of six weeks, both groups of mice were allowed to eat as much high-fat diet as they wanted during their daily 12-hour feeding phase. (Much like many humans, mice have a preference for high-fat food.) Since mice are nocturnal, the 12-hour feeding phase was during the day for those fed during normal sleeping hours and during the night for those fed during naturally wakeful hours. Food was not provided during the other 12 hours of their day.

Our circadian clock, or biological timing system, governs our daily cycles of feeding, activity and sleep, with respect to external dark and light cycles. Recent studies have found the body's internal clock also regulates energy use, suggesting the timing of meals may matter in the balance between caloric intake and expenditure.

The researchers next plan to investigate the molecular mechanisms behind their observation that eating at the "wrong" time can lead to weight gain.

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Quercetin does not enhance athletic performance

The antioxidant quercetin is increasingly being marketed as a supplement that boosts athletic performance, but a new University of Georgia study finds that it is no better than a placebo.

Professor Kirk Cureton, head of the department of kinesiology in the UGA College of Education, and his colleagues tested quercetin in a double-blind, placebo-controlled study that assessed a variety of measures, including the ability of muscles to synthesize energy, cycling performance, perceived exertion and strength loss following exercise. The researchers, whose results appear in the early online edition of the Journal of Applied Physiology, found that quercetin did not improve athletic performance in any of the measures they examined.

“We did not see any performance enhancing effect of quercetin,” Cureton said. “To a certain extent that was disappointing because our hypothesis, based on previous studies in mice, was that we would see positive effects. But our findings are important because they suggest that results from the animal studies shouldn’t be generalized to humans.”

Quercetin is a naturally occurring antioxidant found in the skins of fruits, leafy vegetables, and berries, as well as in black tea, red wine and various fruit juices. It is sold as a supplement in nutrition stores and is an ingredient in sports drinks such as FRS Energy, which is promoted by cyclist Lance Armstrong.

In mice, quercetin has been shown to stimulate the production of mitochondria, which are the energy producing components of muscle cells and other tissue. One study found that mice supplemented with quercetin increased their running endurance by up to 37 percent.

In humans, however, the results have been mixed. An early and widely-cited study reported improvements in performance during a cycling time trial, but Cureton notes that data from the experimental group was not compared to the control group, making the statistical significance of the finding unclear. Published studies on competitive runners and cyclists have found no improvement in performance. A recent published study by the same researchers who reported mitochondrial and endurance increases in mice, however, found that volunteers who consumed a drink containing quercetin saw a 13 percent improvement in endurance. Cureton said the reason for the conflicting results is unknown, but added that several other studies currently in review for publication also have found no performance-enhancing effect.

Cureton and his colleagues hypothesized that the athletes used in the previous studies might not have benefitted from quercetin because they had already maximized their mitochondrial density through aerobic training. To address that possibility, the researchers recruited 30 men who were healthy but not endurance trained and randomly assigned them to either an experimental group or a placebo group.


The experimental group consumed a sports drink containing 250 milligrams of quercetin four times a day for up to 16 days, a dose and duration similar to previous human studies and comparable to studies in mice. The placebo group received the same sports drink without quercetin.

Because the mechanisms of quercetin’s action are unclear, the researchers examined a number of variables in what is the most comprehensive study to date on its effect on athletic performance. The variables included:

The rate at which muscles synthesize energy after strenuous exercise;
Peak oxygen consumption;
The rate of perceived exertion during cycling;
Metabolic changes, such as the percentage of energy derived from fats and carbohydrates (more conditioned individuals tend to use more fat for energy);
Performance on a cycling test; and
Strength loss following prolonged cycling.

Cureton notes that had there been a performance-enhancing effect of quercetin, a sample size of 30 would have been sufficient to detect it. Plant-based compounds related to quercetin, such as resveratrol, have been similarly touted for their health benefits based primarily on animal studies, but Cureton said his findings should serve as a reminder that the gold-standard of science is randomized, double-blinded studies in humans.

“The take home message here is that promising results in mice don’t necessarily translate to humans,” Cureton said.

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Eating frequently = better health!

University of Texas at Austin economist Daniel Hamermesh used data from the American Time Use Survey from the U.S. Bureau of Labor Statistics to examine how much time Americans spend eating meals each day and how much time they spend "grazing" - snacking or drinking while working, watching TV or doing some other activity.

"When their time becomes more valuable, people substitute grazing for eating, essentially switching to multi-tasking," Hamermesh said. "Overall, better health is associated with more time spent eating, but especially with spreading that time over more meals per day."

Hamermesh found that more than half of all adults graze each day, with their grazing time almost equaling the time they spend eating meals. The average American adult spends about two-and-a-half hours eating or grazing every day.

Among the other findings:

• Men graze less but spend more time eating meals than women, a finding that Hamermesh said was surprising because men are more likely to be in the workforce, and grazing while working is commonplace. In all, men spend about three-and-a-half more minutes a day eating meals than women.

• Better-educated people eat more frequently, spend more total time eating, graze more frequently and spend more total time grazing than those with less education. Workers with a post-graduate education, for example, spend about 25 more minutes a day eating meals than high school dropouts.

• Higher earners also spend more time eating individual meals, graze more frequently and spend more time during each individual grazing episode. A worker who earns $75,000 per year spends five more minutes more per day eating, and almost the same extra time grazing, than one who earns $25,000.

• Those who spend more time eating have a lower body mass index (BMI), on average, and view themselves as healthier than those who spend less time eating. The impact on BMI appears to come from eating more frequently and spreading the impact of the food over more meals. Spreading eating time across another meal is associated with a BMI that is 0.2 lower—not huge, but still a few pounds less for a person of average height.

Hamermesh has done extensive research using data from the American Time Use Survey. He has also done research on labor demand, time use, social insurance programs and unusual applications of labor economics to such areas suicide, sleep, beauty and other subjects.

A copy of the report is available at http://www.nber.org/papers/w15277.

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Waist-hip Ratio Better than BMI for Gauging Obesity

in Elderly

Body mass index (BMI) readings may not be the best gauge of obesity in older adults, according to new research from UCLA endocrinologists and geriatricians. Instead, they say, the ratio of waist size to hip size may be a better indicator when it comes to those over 70.

In a new study published online in the peer-reviewed journal Annals of Epidemiology, researchers from the David Geffen School of Medicine at UCLA found that the waist-to-hip circumference ratio was a better yardstick for assessing obesity in high-functioning adults between the ages of 70 and 80, presumably because the physical changes that are part of the aging process alter the body proportions on which BMI is based.

"Basically, it isn't BMI that matters in older adults — it's waist size," said Dr. Preethi Srikanthan, UCLA assistant professor of endocrinology and the study's lead investigator. "Other studies have suggested that both waist size and BMI matter in young and middle-aged adults and that BMI may not be useful in older adults; this is one of the first studies to show that relative waist size does matter in older adults, even if BMI does not matter."

Using data from the MacArthur Successful Aging Study — a longitudinal study of high-functioning men and women between the ages of 70 and 79 — researchers examined all-cause mortality risk over 12 years by BMI, waist circumference and waist-hip ratio. They adjusted for gender, race, baseline age and smoking status. The average age of participants was 74.

Obesity is often associated with premature mortality because it leads to an increased risk of diabetes, heart attack, stroke and other major health problems, the study authors say.

The researchers found no association between all-cause mortality and BMI or waist circumference; the link was only with waist-hip ratio. In women, each 0.1 increase in the waist-hip ratio was associated with a 28 percent relative increase in mortality rate (the number of deaths per 100 older adults per year) in the group sampled. Thus, if the waist-hip ratio rose from 0.8 to 0.9 or from 0.9 to 1.0, it would mean a 28 percent relative increase in the death rate. Put another way, if hip size is 40 inches, an increase in waist size from 32 to 36 inches signaled a 28 percent relative death-rate increase.

The relationship was not graded in men. Instead there was a threshold effect: The rate of dying was 75 percent higher in men with a waist-hip ratio greater than 1.0 — that is, men whose waists were larger than their hips — relative to those with a ratio of 1.0 or lower. There was no such relationship with either waist size or BMI.

The study may have some limitations, the authors noted. For instance, participants' BMI may be underestimated because height and weight were self-reported and older adults tend to report those numbers from their younger, peak years. Also, waist-hip ratios, waist circumference and BMI numbers were based on single measurements, limiting the researchers' ability to gauge how changing body size in old age can affect mortality risk.

Teresa Seeman and Arun S. Karlamangla, both also of UCLA, were co-authors on the study.
The National Institute on Aging funded this research.

The UCLA Division of Geriatrics, within the department of medicine at the David Geffen School of Medicine at UCLA offers comprehensive outpatient and inpatient services at several convenient locations and works closely with other UCLA programs to improve and maintain the quality of life of seniors. UCLA geriatricians are specialists in managing the overall health of people age 65 and older and treating medical disorders that frequently affect the elderly, including falls and immobility, urinary incontinence, memory loss and dementia, arthritis, high blood pressure, heart disease, osteoporosis, and diabetes. UCLA geriatricians can knowledgeably consider and address a broad spectrum of health-related factors — including medical, psychological and social — when treating patients.

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Cutting ‘Hidden’ Salt Could Lower Blood Pressure

Many people think twice before adding a dash of salt to their food, but don’t realize that the majority of dietary sodium comes from packaged foods and eating out, according to a new study.

Reducing sodium intake to recommended levels could result in 11.1 million fewer cases of high blood pressure each year and reduce health care costs by as much as $18 billion as an added benefit, say researchers led by Kartika Palar, a doctoral fellow at Pardee RAND Graduate School.

In the United States, the maximum daily sodium recommendation is 2,300 milligrams but the average person consumes 3,400 milligrams per day, according to the study.
The authors simulated models of different sodium-reduction scenarios, pulling from population-level data on sodium intake, blood pressure and medication use from the National Health and Nutrition Examination Survey, conducted from 1999 to 2004.

The study appears in the September/October 2009 issue of the American Journal of Health Promotion.

Jasminka Ilich, Ph.D., a professor at Florida State University, is not affiliated with the study. Since the surveys were done several years ago, she said, “It is possible that the actual intake of sodium in the population has changed due to already huge public education and efforts to reduce sodium [therefore] rendering lower dollar savings than calculated in this study.”

Ilich agrees with the authors that bringing sodium intake to down to recommended levels would be a major undertaking.

“Sodium is present in all foods, but most abundantly in processed foods. On average, individuals get over 70 percent of their sodium from processed foods. Therefore, there isn’t much leverage in reducing table salt or added salt during cooking,” Ilich said.
“Policy interventions that target processed and restaurant foods, which account for the majority of average sodium intake in the U.S. — not salt added at the table — may be especially promising,” Palar said.

Ilich said the most efficient approach would be to educate the public about reading labels and about substituting or avoiding foods with high sodium content.
She said there is controversy about whether all people with hypertension would see improvement with sodium reduction. “There is another school of thought, according to which only sodium-sensitive people, about 6 percent of the adult population, can lower their blood pressure by reducing sodium intake.” Ilich said.

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Exercise Minimizes Weight Regain

Exercise Reduces Appetite, Burns Fat, And Lowers ‘Defended’ Body Weight

Exercise helps prevent weight regain after dieting by reducing appetite and by burning fat before burning carbohydrates, according to a new study with rats. Burning fat first and storing carbohydrates for use later in the day slows weight regain and may minimize overeating by signaling a feeling of fullness to the brain.

The University of Colorado Denver study also found that exercise prevents the increase in the number of fat cells that occurs during weight regain, challenging the conventional wisdom that the number of fat cells is set and cannot be altered by dietary or lifestyle changes.

These coordinated physiological changes in the brain and the body lower the ‘defended’ weight, that is, the weight that our physiology drives us to achieve, and suggest that the effects of exercise on these physiological processes may make it easier to stay on a diet.

The study is “Regular exercise attenuates the metabolic drive to regain weight after long term weight loss.” Paul S. MacLean, Janine A. Higgins, Holly R. Wyatt, Edward L. Melanson, Ginger C. Johnson, Matthew R. Jackman, Erin D. Giles, Ian E. Brown and James O. Hill, all of the University of Colorado Denver, conducted the study. The American Physiological Society published the research in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology.

How exercise works

Weight gain is, on the surface, remarkably simple, occurring when the calories consumed exceeds the calories expended. On closer examination, the process is remarkably complex. Laboratory, animals eat according to physiological signals that may suppress appetite or arouse the desire to eat. These signals are relatively weak in humans, as their intake is largely influenced by psychological, cognitive and lifestyle factors. After dieting, however, the physiological signals emerge to play a more substantial role in controlling intake. Being persistently hungry after losing weight with restricted diets is a big part of the weight regain problem. Most people are unable to ignore this physiological cue and are pushed by their biology to overeat and regain the weight they worked so hard to lose.

Some people are successful at keeping the weight off, and those tracked by The National Weight Control Registry share a number of common characteristics, including a program of regular exercise. The aim of this investigation was to uncover how exercise affects the body’s physiology to minimize weight regain.

The researchers used obesity-prone rats. For the first 16 weeks, the rats ate a high-fat diet, as much as they wanted, and remained sedentary. They were then placed on a diet. For the following two weeks, the animals ate a low-fat and low-calorie diet, losing about 14% of their body weight. The rats maintained the weight loss by dieting for eight more weeks. Half the rats exercised regularly on a treadmill during this period while the other half remained sedentary.

In the final 8-weeks, the relapse phase of the study, the rats stopped dieting and ate as much low-fat food as they wanted. The rats in the exercise group continued to exercise and the sedentary rats remained sedentary.

Compared to the sedentary rats, the exercisers:

regained less weight during the relapse period

developed a lower ‘defended’ body weight

burned more fat early in the day, and more carbohydrates later in the day

accumulated fewer fat cells and less abdominal fat during relapse

reduced the drive to overeat

enhanced the ability to balance energy intake with energy expended

During feeding, the sedentary group preferentially burned carbohydrates while sending fat from the diet to fat tissue. This preferential fuel use stores more calories because it requires less energy to store fat than to store carbohydrates. In addition, burning away the body’s carbohydrates may contribute to the persistent feeling of hunger and large appetite of the sedentary animals.

Exercise blunted this fuel preference, favoring the burning of fat for energy needs and saving ingested carbohydrates so that they could be used later in the day. Taken together, the exercise led to a much lower appetite and fewer calories ending up in fat tissue.

The researchers also found that exercise prevented the increase in the number of fat cells observed with weight regain in sedentary rats. In sedentary rats, a population of very small, presumably new, fat cells appears early in the relapse process. Small, new fat cells would not only accelerate the process of regain, but also increase fat storage capacity in the abdomen. It would also explain why sedentary rats overshoot their previous weight when they relapse.

Conventional wisdom holds that the number of fat cells is determined by genetics, rather than being regulated by diet or lifestyle. Because this effect of exercise is a novel finding, the team will do further research to demonstrate that exercise is, indeed, preventing the formation of new fat cells early in relapse and not simply altering the size of pre-existing fat cells.

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Estrogen Supplements Not as Effective as Claimed

Dietary supplements claiming to help postmenopausal women with bone health may not be doing what they say, according to new research from Purdue University.

"We found that some plant-derived isoflavones have a modest effect on suppressing bone loss during post-menopause, but more concerning is many dietary supplements that claim to have the power of estrogen do not," said Connie Weaver, distinguished professor of foods and nutrition. "It's buyer beware. Some of the supplements in our study claimed to be substitutes for estrogen, yet they weren't effective at all or weren't as effective as some of the current treatments for osteoporosis."

Women who are menopausal or postmenopausal produce less estrogen, and that leads to bone loss. More than 2 million women in the United States reach menopause each year, according to the National Women's Health Resource Center.

Estrogen hormone replacement therapy was the traditional treatment, but it is no longer recommended for the long term because of links to stroke, embolism and breast cancer. Some individuals have harmful side effects with long-term use of bisphosphonates, the current main class of osteoporosis treatment drugs.

"This is a reminder that it's better to build up a good healthy skeleton than to rely on a drug to fix it later," Weaver said. "Healthy bones can be maintained by a good diet that is rich in calcium and regular exercise that includes strength training."

Weaver, who also is co-director of the Botanicals Research Center for Age Related Diseases, and her team looked at four popular isoflavones: soy cotyledon, soy germ, red clover and kudzu. These plant-derived phytoestrogens are claimed to protect bone health from estrogen loss, which can lead to osteoporosis and even fractures.

The researchers compared the four isoflavones to a traditional bisphosphonate treatment, risedronate and estrogen plus progesterone. These traditional therapies decreased bone loss 22 percent to 24 percent, but only soy isoflavones from the cotyledon and germ significantly decreased bone loss by 9 percent and 5 percent, respectively. The findings are available online and will be published in the October edition of the Journal of Clinical Endocrinology and Metabolism.

The findings also indicate that the soy cotyledon was more effective because of its higher genistein content. Weaver's team is currently evaluating the role of genistein more closely.

"Before, we might have assumed that any isoflavone was equally effective, but we found that for a supplement to work it was

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