Category: Diet and Weight Loss

Scientists at Children's Hospital Oakland Research Institute's (CHORI) Nutrition & Metabolism Center, led by National Medal of Science winner Bruce N. Ames, PhD, have developed a low-calorie fruit-based high fiber vitamin and mineral nutrition bar called the "CHORI-bar" that improves biological indicators (increased HDL-c and glutathione, lowered homocysteine) linked to risk of cardiovascular disease, cognitive decline, and associated decline in anti-oxidant defenses.

The CHORI-bar is intended to help restore optimal nutritional balance in people eating poor diets, and to help transition them to healthier eating habits. The bar is satiating and at only approximately 110 calories per bar, may be helpful in weight reduction programs.

The first research report on the CHORI-bar will appear in the August 2012 FASEB Journal (the Journal of the Federation of American Societies for Experimental Biology) published online on May 1, 2012.

Low intake of many vitamins and minerals is widespread in the U.S. After years of studying the interactions of vitamins and minerals with metabolic processes, Dr.Ames became convinced that modest deficiencies could be contributing to metabolic imbalances that increase risk of diseases associated with obesity and aging, such as diabetes, cancer, and heart disease. In 2006, he proposed the Triage Theory that provided a mechanistic rationale connecting modest vitamin/mineral deficiencies with disease (2), which was strongly supported by subsequent analyses (3,4).

In 2003, Dr. Ames and his colleague Mark Shigenaga, PhD, whose research focuses on the impact of food on gut function, embarked on the development of the CHORI-bar, an economical, low calorie, food supplement that could restore metabolic balance. Intestinal health is now widely recognized to be an important determinant of overall health. Food components that benefit gut health, such as certain soluble fibers and polyphenols, also deficient in typical Western diets, were included in the bar along with a number of other ingredients, all aimed at helping to restore optimal nutrition. Dr. Ames assembled a team of scientists and a collaboration was initiated with the Processed Foods Unit at the United States Department of Agriculture, Agricultural Research Service in Albany, Calif. to assist in the production of a tasty and nutritious bar.

Since the project began, a series of bar formulations were developed, and to date 11 small pilot trials were conducted to refine components and improve palatability from an almost inedible start to a tasty bar. Improvements are continuing to expand the number of disease risk biomarkers favorably impacted by the bar.

The FASEB Journal report describes the prototype bar developed in this program and presents results of a 2-week trial in 25 generally healthy adults led by CHORI-bar team member and pediatric cardiologist Michele Mietus-Snyder, MD. The participants varied in ages and BMI and ate two bars each day for 2-weeks. Included in the panel of assays at the beginning and end of the trial, in addition to standard measures of lipids, glucose metabolism, and inflammation, was ion mobility analysis (developed by CHORI Senior Scientist Ronald Krauss, MD, (5)) used to quantify lipoprotein sub-fractions, and a liquid chromatography linked tandem mass-spectrometry (LD/MS/MS) assay (developed by CHORI Associate Staff Scientist Jung Suh, MPH, PhD (6)) to measure thiol compounds and amino acid metabolites. This expanded panel of assays permitted a more in depth look at biomarkers and at clues to mechanisms underlying effects of the CHORI-bar.

Impressively, favorable metabolic changes occurred after only 2-weeks of bar intake, without guidelines as to whether to use the bar as a meal replacement or a supplement. For example, increased HDL cholesterol has been reported after intake of several individual bar ingredients, but at much higher doses than what is present in the bar. The possibility that bar ingredients are acting additively or synergistically is supported by some preliminary evidence.

Two examples from the results of this trial emphasize the fact that, with the right mixture of food components, pharmacological or supraphysiological doses are not needed to positively move metabolism in a healthy direction.

1) It is difficult to both raise HDL and lower homocysteine either pharmacologically or with dietary interventions. "Heart-healthy" diets most consistently linked to an increase in HDL-c are those that emphasize fat quality more than quantity, such as the Mediterranean diet. The CHORI-bar combines aspects of the Mediterranean diet with the most biologically active form of folate (5-methyl-tetrahydrofolate). The latter is expected to bypass the need for high levels of folate required to keep homocysteine at a healthy level in individuals with the TT MTHFR polymorphism, which is present in half the U.S. population.

2) Glutathione is the principal regulator of the cellular redox environment, and is important for preventing oxidative stress. Glutathione declines with age and is low in many diseases. Few drugs and only high doses of certain food constituents have been reported to raise glutathione, but only 2-weeks consumption of the bar was required.

Current research is continuing on several fronts. In addition to its potential to have an impact on public health, the CHORI-bar is a research tool that can elucidate mechanisms by which food components in the bar interact with metabolic pathways to favorably impact disease-relevant biomarkers. Two additional bars have been developed that expand the number of biomarkers improved by the bar to include measures of insulin resistance, inflammation, and additional elements of lipid metabolism, notably LDL cholesterol. Efforts are underway to combine attributes of all 3 bars in a single bar. A series of clinical trials have also been initiated that test the efficacy of the CHORI-bar in improving metabolism in individuals with diseases accompanied by metabolic dysregulation favorably impacted by the bar, including obesity, asthma, and hypertension. And finally, development of additional biomarker assays is underway to expand the classes of metabolic changes that can be detected, such as several different types of DNA damage.

NewsPsychology (Jan. 26, 2012) — A patient’s body mass index (BMI) may not be the only factor at play when a physician diagnoses a patient as obese. According to a new study led by researchers at the Johns Hopkins Bloomberg School of Public Health, the diagnosis could also depend on the weight of your physician. Researchers examined the impact of physician BMI on obesity care and found that physicians with a normal BMI, as compared to overweight and obese physicians, were more likely to engage their obese patients in weight loss discussions (30 percent vs. 18 percent) and more likely to diagnose a patient as obese if they perceived the patient’s BMI met or exceed their own (93 percent vs. 7 percent).

The results are featured in the January issue of Obesity.

“Our findings indicate that physicians with normal BMI more frequently reported discussing weight loss with patients than overweight or obese physicians. Physicians with normal BMI also have greater confidence in their ability to provide diet and exercise counseling and perceive their weight loss advice as trustworthy when compared to overweight or obese physicians,” said Sara Bleich, PhD, lead author of the study and an assistant professor with the Bloomberg School’s Department of Health Policy and Management. “In addition, obese physicians had greater confidence in prescribing weight loss medications and were more likely to report success in helping patients lose weight.”

Using a national cross-sectional survey of 500 primary care physicians, Bleich and colleagues from the Johns Hopkins School of Medicine assessed the impact of physician BMI on obesity care, physician self-efficacy, perceptions of role modeling and perceptions of patient trust in weight loss advice. Physicians with a self-reported BMI below 25 kg/m2 were considered to be of normal weight and physicians reporting a BMI at or above 25 kg/m2 were considered overweight or obese.

According to the Centers for Disease Control and Prevention (CDC) obesity affects more than one-third of the U.S. adult population and is estimated to cost $147 billion annually in related health care costs. Obesity increases the risk of many adverse health conditions including type 2 diabetes, coronary heart disease, stroke and high blood pressure. Despite guidelines for physicians to counsel and treat obese patients, previous studies have found only one-third of these patients report receiving an obesity diagnosis or weight-related counseling from their physicians.

“While our results suggest that obesity practices and beliefs differ by physician BMI, more research is need to understand the full impact of physician BMI on obesity care,” suggest the study’s authors.

“Physician self-efficacy to care for obese patients, regardless of their BMI, may be improved by targeting physician well-being and enhancing the quality of obesity-related training in medical school, residency or continuing medical education,” adds Bleich.

The research was supported by in part by the National Heart, Lung and Blood Institute and the Health Resources and Services Administration.

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Story Source:

The above story is reprinted from materials provided by Johns Hopkins Bloomberg School of Public Health, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Sara N. Bleich, Wendy L. Bennett, Kimberly A. Gudzune, Lisa A. Cooper. Impact of Physician BMI on Obesity Care and Beliefs. Obesity, 2012; DOI: 10.1038/oby.2011.402

A clear association between obesity and pain — with higher rates of pain identified in the heaviest individuals — was found in a study of more than one million Americans published January 19 in the online edition of Obesity. In "Obesity and Pain Are Associated in the United States," Stony Brook University researchers Arthur A. Stone, PhD., and Joan E. Broderick, Ph.D. report this finding based on their analysis of 1,010,762 respondents surveyed via telephone interview by the Gallop Organization between 2008 and 2010.

Previous small-scale studies have shown links between obesity and pain. The Stony Brook study took a very large sample of American men and women who answered health survey questions. The researchers calculated respondents' body mass index (BMI) based on questions regarding height and weight. Respondents answered questions about pain, including if they "experienced pain yesterday."

"Our findings confirm and extend earlier studies about the link between obesity and pain. These findings hold true after we accounted for several common pain conditions and across gender and age," says Dr. Stone, Distinguished Professor and Vice Chair, Department of Psychiatry and Behavioral Science, Stony Brook University School of Medicine, and an expert on patient reported measures of health, pain, and well-being.

Sixty three percent of the 1,010,762 people who responded to the survey were classified as overweight (38 percent) or obese (25 percent). Obese respondents were further classified into one of three obesity levels as defined by the World Health Organization. In comparison to individuals with low to normal weight, the overweight group reported 20 percent higher rates of pain. The percent increase of reported pain in comparison to the normal weight group grew rapidly in the obese groups: 68 percent higher for Obese 1 group, 136 percent higher for Obese 2 group, and 254 percent higher for Obese 3 group.

"We wanted to explore this relationship further by checking to see if it was due to painful diseases that cause reduced activity, which in turn causes increased weight," says Joan E. Broderick, Ph.D., Associate Professor in the Department of Psychiatry and Behavioral Science and School of Public Health at Stony Brook University, and lead investigator of a National Institutes of Health-funded study on how arthritis patients manage their own pain.

"We found that 'pain yesterday' was definitely more common among people with diseases that cause bodily pain. Even so, when we controlled for these specific diseases, the weight-pain relationship held up. This finding suggests that obesity alone may cause pain, aside from the presence of painful diseases," Dr. Broderick explains.

Interestingly, the pain that obese individuals reported was not driven exclusively by musculoskeletal pain, a type of pain that individuals carrying excess weight might typically experience.

Drs. Broderick and Stone also suggest that there could be several plausible explanations for the close obesity/pain relationship. These include the possibility that having excess fat in the body triggers complex physiological processes that result in inflammation and pain; depression, often experienced by obese individuals, is also linked to pain; and medical conditions that cause pain, such as arthritis, might result in reduced levels of exercise thereby resulting in weight gain. The researchers also indicated that the study showed as people get older, excess weight is associated with even more pain, which suggests a developmental process.

Drs. Broderick and Stone believe that the study findings support the importance of metabolic investigations into the causes of pain, as well as the need for further investigation of the obesity — pain link in U.S. populations.

When people in the U.S. are asked to provide their weight for research surveys, they underestimate their weight and overestimate their height, despite numerous public reports about increasing rates of obesity. Whites are more likely to do so than Blacks or Hispanics, a new study finds.

Many surveys about body weight rely on participants to report their height and weight, because it is less expensive and easier than measuring. Under-reporting one's body mass index (BMI) is common across all gender and ethnic groups, according to the study, but the researchers don't believe the practice makes a huge impact on how we view the nation's obesity numbers.

"In terms of studies examining risk factors of obesity, I don't think the under-reporting is a huge problem," said lead author Ming Wen, Ph.D., an associate professor in the Department of Sociology at the University of Utah.

The study, which appears in the journal Ethnicity & Disease, relied on data from the 2007-2008 National Health and Nutrition Examination Survey (NHANES) and looked at reports from 2,672 men and 2,671 women. NHANES includes both self-reported and measured height, weight, and BMI grouped by gender and ethnicity. The researchers also looked at overweight and obesity status, education, age and poverty status.

Wen and her colleague, Lori Kowaleski-Jones, Ph.D., found that in all ethnic groups, both men and women overestimate their height. Women also under-report their BMI more than men do, and White women are more likely to do so compared to Black and Hispanic women. The authors speculated this was because White women have a stronger social "desire for a lean body" and were more acutely aware of their weight problems. Those who were overweight, in the oldest age group and who had a college education were also more likely to under-report their BMI.

The researchers said, however, the under-reporting bias is "generally small" with the range of difference between measured and self-reported BMI falling within the 1 BMI unit range.

Wen said their results highlight the care that should be taken when making comparisons of BMI across different U.S. socio-demographic groups.

Dori Rosenberg, Ph.D., an assistant investigator at Group Health Research Institute in Seattle who specializes in obesity prevention and control, agreed.

"The paper underscores that there may be slight differences by race or ethnicity which should be emphasized when making conclusions at the population level based on reported height and weight," she said. "Therefore, when studies are able to use measured height and weight, they should do so."

When it comes to diets, cookies and cake are off the menu. Now, in a surprising discovery, researchers from Tel Aviv University have found that dessert, as part of a balanced 600-calorie breakfast that also includes proteins and carbohydrates, can help dieters to lose more weight — and keep it off in the long run.

They key is to indulge in the morning, when the body's metabolism is at its most active and we are better able to work off the extra calories throughout the day, say Prof. Daniela Jakubowicz, Dr. Julio Wainstein and Dr. Mona Boaz of Tel Aviv University's Sackler Faculty of Medicine and the Diabetes Unit at Wolfson Medical Center, and Prof. Oren Froy of Hebrew University Jerusalem.

Attempting to avoid sweets entirely can create a psychological addiction to these same foods in the long-term, explains Prof. Jakubowicz. Adding dessert items to breakfast can control cravings throughout the rest of the day. Over the course of a 32 week-long study, detailed in the journal Steroids, participants who added dessert to their breakfast — cookies, cake, or chocolate — lost an average of 40 lbs. more than a group that avoided such foods. What's more, they kept off the pounds longer.

The scale tells the tale

A meal in the morning provides energy for the day's tasks, aids in brain functioning, and kick-starts the body's metabolism, making it crucial for weight loss and maintenance. And breakfast is the meal that most successfully regulates ghrelin, the hormone that increases hunger, explains Prof. Jakubowicz. While the level of ghrelin rises before every meal, it is suppressed most effectively at breakfast time.

Basing their study on this fact, the researchers hoped to determine whether meal time and composition impacted weight loss in the short and long term, says Prof. Jakubowicz, or if it was a simple matter of calorie count.

One hundred and ninety three clinically obese, non-diabetic adults were randomly assigned to one of two diet groups with identical caloric intake — the men consumed 1600 calories per day and the women 1400. However, the first group was given a low carbohydrate diet including a small 300 calorie breakfast, and the second was given a 600 calorie breakfast high in protein and carbohydrates, always including a dessert item (i.e. chocolate).

Halfway through the study, participants in both groups had lost an average of 33 lbs. per person. But in the second half of the study, results differed drastically. The participants in the low-carbohydrate group regained an average of 22 lbs. per person, but participants in the group with a larger breakfast lost another 15 lbs. each. At the end of the 32 weeks, those who had consumed a 600 calorie breakfast had lost an average of 40 lbs. more per person than their peers.

Realistic in the long run

One of the biggest challenges that people face is keeping weight off in the long-term, says Prof. Jakubowicz. Ingesting a higher proportion of our daily calories at breakfast makes sense. It's not only good for body function, but it also alleviates cravings. Highly restrictive diets that forbid desserts and carbohydrates are initially effective, but often cause dieters to stray from their food plans as a result of withdrawal-like symptoms. They wind up regaining much of the weight they lost during the diet proper.

Though they consumed the same daily amount of calories, "the participants in the low carbohydrate diet group had less satisfaction, and felt that they were not full," she says, noting that their cravings for sugars and carbohydrates were more intense and eventually caused them to cheat on the diet plan. "But the group that consumed a bigger breakfast, including dessert, experienced few if any cravings for these foods later in the day."

Ultimately, this shows that a diet must be realistic to be adopted as part of a new lifestyle. Curbing cravings is better than deprivation for weight loss success, Prof. Jakubowicz concludes.

Researchers at the University of Turku and Aalto University have found new evidence for the role of the brain in obesity.

In most western countries the annual increase in the prevalence and the severity of obesity is currently substantial. Although obesity typically results simply from excessive energy intake, it is currently unclear why some people are prone to overeating and gaining weight.

Because the central nervous system is intimately involved in processing of hunger signals and controlling food intake, it is possible that the cause of weight gain and obesity might be in the brain.

Researchers at the University of Turku and Aalto University have now found new evidence for the role of the brain in obesity. The researchers measured the functioning brain circuits involved in with multiple brain imaging methods.

The results revealed that in obese versus lean individuals, brain glucose metabolism was significantly higher in the brain's striatal regions, which are involved in processing of rewards. Moreover, obese individual's reward system responded more vigorously to food pictures, whereas responses in the frontal cortical regions involved in cognitive control were dampened.

"The results suggest that obese individuals' brains might constantly generate signals that promote eating even when the body would not require additional energy uptake," says Adjunct Professor Lauri Nummenmaa from the University of Turku.

"The results highlight the role of the brain in obesity and weight gaining. The results have major implications on the current models of obesity, but also on development of pharmacological and psychological treatments of obesity," Nummenmaa says.

The participants were morbidly obese individuals and lean, healthy controls. Their brain glucose metabolism was measured with positron emission tomography during conditions in which the body was satiated in terms of insulin signalling. Brain responses to pictures of foods were measured with functional magnetic resonance imaging.

The research is funded by the Academy of Finland, Turku University Hospital, University of Turku, Åbo Akademi University and Aalto University.

The results were published on January 27th, 2012 in scientific journal PLoS ONE.

 An Oregon State University researcher has reviewed the body of evidence around weight loss supplements and has bad news for those trying to find a magic pill to lose weight and keep it off — it doesn't exist.

Melinda Manore reviewed the evidence surrounding hundreds of weight loss supplements, a $2.4 billion industry in the United States, and said no research evidence exists that any single product results in significant weight loss — and many have detrimental health benefits.

The study is online in the International Journal of Sport Nutrition and Exercise Metabolism.

A few products, including green tea, fiber and low-fat dairy supplements, can have a modest weight loss benefit of 3-4 pounds (2 kilos), but it is important to know that most of these supplements were tested as part of a reduced calorie diet.

"For most people, unless you alter your diet and get daily exercise, no supplement is going to have a big impact," Manore said.

Manore looked at supplements that fell into four categories: products such as chitosan that block absorption of fat or carbohydrates, stimulants such as caffeine or ephedra that increase metabolism, products such as conjugated linoleic acid that claim to change the body composition by decreasing fat, and appetite suppressants such as soluble fibers.

She found that many products had no randomized clinical trials examining their effectiveness, and most of the research studies did not include exercise. Most of the products showed less than a two-pound weight loss benefit compared to the placebo groups.

"I don't know how you eliminate exercise from the equation," Manore said. "The data is very strong that exercise is crucial to not only losing weight and preserving muscle mass, but keeping the weight off."

Manore, professor of nutrition and exercise sciences at OSU, is on the Science Board for the President's Council on Fitness, Sports and Nutrition. Her research is focused on the interaction of nutrition and exercise on health and performance.

"What people want is to lose weight and maintain or increase lean tissue mass," Manore said. "There is no evidence that any one supplement does this. And some have side effects ranging from the unpleasant, such as bloating and gas, to very serious issues such as strokes and heart problems."

As a dietician and researcher, Manore said the key to weight loss is to eat whole grains, fruits, vegetables and lean meats, reduce calorie intake of high-fat foods, and to keep moving. Depending on the individual, increasing protein may be beneficial (especially for those trying to not lose lean tissue), but the only way to lose weight is to make a lifestyle change.

"Adding fiber, calcium, protein and drinking green tea can help," Manore said. "But none of these will have much effect unless you exercise and eat fruits and vegetables."

Manore's general guidelines for a healthy lifestyle include:

• Do not leave the house in the morning without having a plan for dinner. Spontaneous eating often results in poorer food choices.
• If you do eat out, start your meal with a large salad with low-calorie dressing or a broth-based soup. You will feel much fuller and are less likely to eat your entire entrée. Better yet: split your entrée with a dining companion or just order an appetizer in addition to your soup or salad.
• Find ways to keep moving, especially if you have a sedentary job. Manore said she tries to put calls on speaker phone so she can walk around while talking. During long meetings, ask if you can stand or pace for periods so you don't remain seated the entire time
• Put vegetables into every meal possible. Shred vegetables into your pasta sauce, add them into meat or just buy lots of bags of fruits/vegetables for on-the-go eating.
• Increase your fiber. Most Americans don't get nearly enough fiber. When possible, eat "wet" sources of fiber rather than dry — cooked oatmeal makes you feel fuller than a fiber cracker.
• Make sure to eat whole fruits and vegetables instead of drinking your calories. Eat an apple rather than drink apple juice. Look at items that seem similar and eat the one that physically takes up more space. For example, eating 100 calories of grapes rather than 100 calories of raisins will make you feel fuller.
• Eliminate processed foods. Manore said research increasingly shows that foods that are harder to digest (such as high fiber foods) have a greater "thermic effect" — or the way to boost your metabolism.

Women who work a rotating (irregular) schedule that includes three or more night shifts per month, in addition to day and evening working hours in that month, may have an increased risk of developing type 2 diabetes when compared with women who only worked days or evenings, according to a new study led by researchers at Harvard School of Public Health (HSPH). In addition, the researchers found that extended years of rotating night shift work was associated with weight gain, which may contribute to the increased risk of type 2 diabetes.

Previous studies have focused on the association between shift work and risk of cancer and cardiovascular disease. The HSPH study is the largest study so far to look at the link between shift work and type 2 diabetes and the first large study to follow women. The findings were published online Dec. 6, 2011 in the open access journal PLoS Medicine.

"Long-term rotating night shift work is an important risk factor for the development of type 2 diabetes and this risk increases with the numbers of years working rotating shifts," said An Pan, research fellow in HSPH's Department of Nutrition and the study's lead author.

The researchers, led by Pan and senior author Frank Hu, professor of nutrition and epidemiology, analyzed data on more than 69,269 U.S. women, ages 42 to 67, in the Nurses' Health Study I, tracked from 1988 to 2008, and 107,915 women, ages 25 to 42, in the Nurses' Health Study II, tracked from 1989 to 2007. About 60% of the nurses performed more than one year of rotating night shift work at baseline; about 11% in Nurses' Health Study I had more than 10 years of rotating night shift work at baseline, and about 4% in Nurses' Health Study II worked more than 10 years of rotating night shifts at baseline, and this proportion increased during the follow-up.

The researchers found that the longer women worked rotating night shifts, the greater their risk of developing type 2 diabetes. Those women who worked rotating night shifts for three to nine years faced a 20% increased risk; women who worked nights for 10 to 19 years had a 40% rise in risk; and women who worked night shifts for over 20 years were 58% more at risk. In addition, women who worked rotating night shifts gained more weight and were more likely to become obese during the follow-up.

After taking into account body weight in the analyses, the increased risk of type 2 diabetes for women who worked rotating night shifts was reduced but remained statistically significant. For example, women who worked rotating night shifts for more than 20 years had 24% increased risk. These findings indicate that the relationship between night shift work and type 2 diabetes is partly explained by increased weight.

While the findings need to be confirmed in men and in some ethnic groups (96% of the participants were white Caucasians) and further studies are needed to identify underlying mechanisms for the association, the results are of potential public health significance due to the large number of workers who work rotating night shifts.

According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 15 million Americans work full time on evening shifts, night shifts, rotating shifts, or other irregular schedules. Shift work has been shown to disrupt sleeping patterns and other body rhythms, and has been associated with obesity and metabolic syndrome, conditions associated with type 2 diabetes.

"This study raises the awareness of increased obesity and diabetes risk among night shift workers and underscores the importance of improving diet and lifestyle for primary prevention of type 2 diabetes in this high risk group," said Hu. Studies also are needed to evaluate type 2 diabetes risk in other shift work schedules, such as evening shifts or permanent night shifts.

Support for this study was provided by the National Institutes of Health and career development awards from the National Heart, Lung, and Blood Institute.

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Journal Reference:

1. An Pan, Eva S. Schernhammer, Qi Sun, Frank B. Hu. Rotating Night Shift Work and Risk of Type 2 Diabetes: Two Prospective Cohort Studies in Women. PLoS Medicine, 2011; 8 (12): e1001141 DOI: 10.1371/journal.pmed.1001141

There is no doubt that eating a balanced diet is essential for maintaining a healthy body weight as well as appropriate arousal and energy balance, but the details about how the nutrients we consume are detected and processed in the brain remain elusive. Now, a research study discovers intriguing new information about how dietary nutrients influence brain cells that are key regulators of energy balance in the body.

The study, published by Cell Press in the November 17 issue of the journal Neuron, suggests a cellular mechanism that may allow brain cells to translate different diets into different patterns of activity.

"The nutritional composition of meals, such as the protein:carbohydrate (sugar) ratio has long been recognized to affect levels of arousal and attention," explains senior study author, Dr. Denis Burdakov, from the University of Cambridge. "However, while certain specialized neurons are known to sense individual nutrients, such as the sugar glucose, it remains unclear how typical dietary combinations of nutrients affect energy balance-regulating brain circuits."

Dr. Burdakov and colleagues studied how physiological mixtures of nutrients influenced "orexin/hypocretin" neurons, which are known to be critical regulators of wakefulness and energy balance in the body. Previous research had demonstrated that orexin/hypocretin neurons are inhibited by glucose. Surprisingly, the current study revealed that physiologically relevant mixtures of amino acids, the nutrients derived from proteins (such as egg white), stimulated and activated the orexin/hypocretin neurons. The researchers went on to show that when orexin/hypocretin neurons were simultaneously exposed to amino acids and sugars, the amino acids served to suppress the inhibitory influence of glucose.

Taken together, these results support a new and more complex nutrient-specific model for dietary regulation of orexin/hypocretin neurons. "We found that activity in the orexin/hypocretin system is regulated by macronutrient balance rather than simply by the caloric content of the diet, suggesting that the brain contains not only energy-sensing cells, but also cells that can measure dietary balance," concludes Dr Burdakov. "Our data support the idea that the orexin/hypocretin neurons are under a 'push-pull' control by sugars and proteins. Interestingly, although behavioral effects are beyond the scope of our study, this cellular model is consistent with reports that when compared with sugar-rich meals, protein-rich meals are more effective at promoting wakefulness and arousal."

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Journal Reference:

1. Mahesh M. Karnani, John Apergis-Schoute, Antoine Adamantidis, Lise T. Jensen, Luis de Lecea, Lars Fugger, Denis Burdakov. Activation of Central Orexin/Hypocretin Neurons by Dietary Amino Acids. Neuron, 2011; 72 (4): 616 DOI: 10.1016/j.neuron.2011.08.027

Contrary to popular belief, most college students don't gain anywhere near 15 pounds during their freshman year, according to a new nationwide study.

Rather than adding "the freshman 15," as it is commonly called, the average student gains between about 2.5 and 3.5 pounds during the first year of college.

And college has little to do with the weight gain, the study revealed. The typical freshman only gains about a half-pound more than a same-age person who didn't go to college.

"The 'freshman 15' is a media myth," said Jay Zagorsky, co-author of the study and research scientist at Ohio State University's Center for Human Resource Research.

"Most students don't gain large amounts of weight. And it is not college that leads to weight gain — it is becoming a young adult."

The results suggest that media reporting of the freshman 15 myth may have serious implications.

"Repeated use of the phrase 'the freshman 15,' even if it is being used just as a catchy, alliterative figure of speech, may contribute to the perception of being overweight, especially among young women," Zagorsky said.

"Weight gain should not be a primary concern for students going off to college."

Zagorsky conducted the study with Patricia Smith of the University of Michigan-Dearborn. The study will appear in the December 2011 issue of the journal Social Science Quarterly.

The study uses data from 7,418 young people from around the country who participated in the National Longitudinal Survey of Youth 1997. The NLSY97 interviewed people between the ages of 13 and 17 in 1997 and then interviewed the same people each year since then. The NLSY is conducted by Ohio State's Center for Human Resource Research for the U.S. Bureau of Labor Statistics.

Among many other questions, respondents were asked their weight and college status each year.

Other studies have shown that college students tend to underestimate their weight by half a pound to 3 pounds. But if people are consistent in underestimating their weight from year to year, it would not impact these results, Zagorsky said.

The study found that women gained an average of 2.4 pounds during their freshman year, while men gained an average of 3.4 pounds. No more than 10 percent of college freshman gained 15 pounds or more — and a quarter of freshman reported actually losing weight during their first year.

"It's worth noting that while there's this focus on weight gain among freshman, we found that one in four actually lost weight," Zagorsky said.

The researchers examined a variety of factors that may be associated with freshman weight gain, including whether they lived in a dormitory, went to school full or part time, pursued a two-year or four-year degree, went to a private or public institution, or was a heavy drinker of alcohol (consuming six or more drinks on at least four days per month.)

None of these factors made a significant difference on weight gain, except for heavy drinking. Even then, those who were heavy drinkers gained less than a pound more than students who did not drink at that level.

Zagorsky said it was particularly significant that dorm living did not add to weight gain, since one hypothesis has been that the dorm environment encourages weight gain during the freshman year.

"There has been concern that access to all-you-can-eat cafeterias and abundant fast food choices, with no parental oversight, may lead to weight gain, but that doesn't seem to hold true for most students," he said.

The results do show, however, that college students do gain weight steadily over their college years.

The typical woman gains between seven and nine pounds, while men gain between 12 and 13 pounds.

"Not only is there not a 'freshman 15,' there doesn't appear to be even a 'college 15' for most students," Zagorsky said.

Over the course of the entire college career, students who both worked and attended college gained an extra one-fifth of a pound for each month they worked.

The researchers also examined what happened to college students' weight after they graduated. They found that in the first four years after college, the typical respondent gained another 1.5 pounds per year.

"College students don't face an elevated risk of obesity because they gain a large amount of weight during their freshman year," Zagorsky said.

"Instead, they have moderate but steady weight gain throughout early adulthood. Anyone who gains 1.5 pounds every year will become obese over time, no matter their initial weight."

Although most students don't need to worry about large weight gains their freshman year, Zagorsky said they still should focus on a healthy lifestyle.

"Students should begin developing the habit of eating healthy foods and exercising regularly. Those habits will help them throughout their lives."

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Journal Reference:

1. Jay L. Zagorsky, Patricia K. Smith. The Freshman 15: A Critical Time for Obesity Intervention or Media Myth?Social Science Quarterly, 2011; DOI: 10.1111/j.1540-6237.2011.00823.x