Category: Diet and Weight Loss

Despite the increasing awareness of the problem of obesity in the United States, most Americans don't know whether they are gaining or losing weight, according to new research from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.

In 1714, the British government held a contest. They offered a large cash prize to anyone who could solve the vexing "longitude problem" — how to determine a ship's east/west position on the open ocean — since none of their naval experts had been able to do so.

Yo-yo dieting — the repetitive loss and regain of body weight, also called weight cycling — is prevalent in the Western world, affecting an estimated 10 percent to 40 percent of the population. The degree to which weight cycling may impact metabolism or thwart a person's ability to lose weight in the long run has been unclear — until now.

A Loyola study of high school students provides new evidence that a person's circle of friends may influence his or her weight.

Students were more likely to gain weight if they had friends who were heavier than they were. Conversely, students were more likely to get trimmer — or gain weight at a slower pace — if their friends were leaner than they were.

Results of the study by David Shoham, PhD, and colleagues are published in the journal PLoS ONE. Shoham is an assistant professor in the Department of Preventive Medicine & Epidemiology of Loyola University Chicago Stritch School of Medicine.

A student's social network also influences how active he or she is in sports. (By social networks, researchers mean face-to-face friends, not Facebook friends.)

"These results can help us develop better interventions to prevent obesity," Shoham said. "We should not be treating adolescents in isolation."

The study was designed to determine the reason why obesity and related behaviors cluster in social networks. Is it because friends influence one another's behavior? (This explanation is called "social influence.") Or is it simply because lean adolescents tend to have lean friends and heavier adolescents tend to have heavier friends? (This explanation is called "homophily, or more informally, "Birds of a feather flock together.") Researchers used a sophisticated statistical technique to determine how much of the link between obesity and social networks is due to social influence and how much is due to homophily. This statistical technique is called "stochastic actor-based model," or SABM.

The researchers examined data from two large high schools that participated in the National Longitudinal Study of Adolescent Health (Add Health). One school, referred to as "Jefferson High," is in a rural area and has mostly white students. The second school, "Sunshine High," is an urban school with a substantial racial and ethnic diversity. Students were surveyed during the 1994-95 school year and surveyed again the following school year.

Researchers examined data from 624 students at Jefferson High and 1,151 students at Sunshine High. Previously, researchers not affiliated with the current study asked students about their weight, friendships, sports activities and screen time. The body size measure they used was body mass index (BMI), which is calculated from a student's height and weight. A BMI over 25 is considered overweight and a BMI over 30 is considered obese.

Researchers found that part of the reason why obesity clusters in social networks was due to the way students selected friends. But even after controlling for this friend-selecting process, there still was a significant link between obesity and a student's circle of friends. For example, if a borderline overweight student at Jefferson High School had lean friends (average BMI 20), there was a 40 percent chance the student's BMI would drop in the future and a 27 percent chance it would increase. But if a borderline overweight student had obese friends (average BMI 30), there was a 15 percent chance the student's BMI would decrease and a 56 percent chance it would increase.

The findings, researchers concluded, show that social influence "tends to operate more in detrimental directions, especially for BMI; a focus on weight loss is therefore less likely to be effective than a primary prevention strategy against weight gain. Effective interventions will be necessary to overcome these barriers, requiring that social networks be considered rather than ignored."

Shoham noted the study has several limitations. All of the measures were based on self-reported data, which has known biases. Social network studies are observational rather than experimental, which limits researchers' ability to call the associations causal. The model also makes assumptions about how friendships form, are maintained, and dissolve over time, and these assumptions could not be directly tested. Also, the data were collected more than a decade ago — before Facebook and at a time when childhood obesity rates were much lower. Nevertheless, Shoham believes these results add to the vigorous debate over the relative importance of selection and peer influence in network studies of health. "Our results support the operation of both homophily and influence," he said. "Of course, no one study should ever be taken as conclusive and our future work will attempt to address many of these limitations."

As the United States confronts the growing epidemic of obesity among children and adults, a team of University of Colorado School of Medicine obesity researchers concludes that what the nation needs is a new battle plan — one that replaces the emphasis on widespread food restriction and weight loss with an emphasis on helping people achieve "energy balance" at a healthy body weight.

In a paper published in the July 3 issue of the journal Circulation, James O. Hill, PhD. and colleagues at the Anschutz Health and Wellness Center take on the debate over whether excessive food intake or insufficient physical activity cause obesity, using the lens of energy balance — which combines food intake, energy expended through physical activity and energy (fat) storage — to advance the concept of a "regulated zone," where the mechanisms by which the body establishes energy balance are managed to overcome the body's natural defenses towards preserving existing body weight. This is accomplished by strategies that match food and beverage intake to a higher level of energy expenditure than is typical in America today, enabling the biological system that regulates body weight to work more effectively. Additional support for this concept comes from many studies showing that higher levels of physical activity are associated with low weight gain whereas comparatively low levels of activity are linked to high weight gain over time.

"A healthy body weight is best maintained with a higher level of physical activity than is typical today and with an energy intake that matches," explained Hill, professor of pediatrics and medicine and executive director of the Anschutz Health and Wellness Center at the University of Colorado Anschutz Medical Campus and the lead author of the paper. "We are not going to reduce obesity by focusing only on reducing food intake. Without increasing physical activity in the population we are simply promoting unsustainable levels of food restriction. This strategy hasn't worked so far and it is not likely to work in the future.

As Dr. Hill explains, "What we are really talking about is changing the message from 'Eat Less, Move More" to 'Move More, Eat Smarter.' "

The authors argue that preventing excessive weight gain is a more achievable goal than treating obesity once it is present. Here, the researchers stress that reducing calorie intake by 100 calories a day would prevent weight gain in 90 percent of the adult population and is achievable through small increases in physical activity and small changes in food intake.

People who have a low level of physical activity have trouble achieving energy balance because they must constantly use food restriction to match energy intake to a low level of energy expenditure. Constant food restriction is difficult to maintain long-term and when it cannot be maintained, the result is positive energy balance (when the calories consumed are greater than the calories expended) and an increase in body mass, of which 60 percent to 80 percent is usually body fat. The increasing body mass elevates energy expenditure and helps reestablish energy balance. In fact, the researchers speculate that becoming obese may be the only way to achieve energy balance when living a sedentary lifestyle in a food-abundant environment.

Using an exhaustive review of the energy balance literature as the basis, the researchers also refuted the popular theory that escalating obesity rates can be attributed exclusively to two factors — the change in the American diet and the rise in overall energy intake without a compensatory increase in energy expenditure. Using rough estimates of increases in food intake and decreases in physical activity from 1971 to 2000, the researchers calculated that were it not for the physiological processes that produce energy balance, American adults would have experienced a 30 to 80 fold increase in weight gain during that period, which demonstrates why it is not realistic to attribute obesity solely to caloric intake or physical activity levels. In fact, energy expenditure has dropped dramatically over the past century as our lives now require much less physical activity just to get through the day. The authors argue that this drop in energy expenditure was a necessary prerequisite for the current obesity problem, which necessitates adding a greater level of physical activity back into our modern lives.

"Addressing obesity requires attention to both food intake and physical activity, said co-author John Peters, PhD., assistant director of the Anschutz Health and Wellness Center. "Strategies that focus on either alone will not likely work."

In addition, the researchers conclude that food restriction alone is not effective in reducing obesity, explaining that although caloric restriction produces weight loss, this process triggers hunger and the body's natural defense to preserve existing body weight, which leads to a lower resting metabolic rate and notable changes in how the body burns calories. As a result, energy requirements after weight loss can be reduced from 170 to 250 calories for a 10 percent weight loss and from 325 to 480 calories for a 20 percent weight loss. These findings provide insight concerning weight loss plateau and the common occurrence of regaining weight after completing a weight loss regimen.

Recognizing that energy balance is a new concept for to the public, the researchers call for educational efforts and new information tools that will teach Americans about energy balance and how food and physical activity choices affect energy balance.

A Web-based program featuring successful strategies of others who have lost weight may be an effective strategy for weight loss, according to Penn State College of Medicine researchers.

Researchers created a website called AchieveTogether and evaluated the weight-loss success of users. They compared users with a group of people attempting to lose weight on their own, and then allowed that second group access to the site 12 weeks later.

"Internet-based weight loss programs could help address the obesity epidemic, as they can be widely shared and used with low costs," said Jennifer L. Kraschnewski, M.D., M.P.H., assistant professor of medicine and public health sciences. "Existing Internet-based weight-loss strategies have largely promoted weight-loss strategies designed by health professionals, including goal-setting and features to promote social interaction. These programs have had modest short-term effects, suggesting that exploring alternative approaches may be beneficial."

The researchers used positive deviance to design their Web-based program. Positive deviance is the idea that solutions to problems exist within a population experiencing that problem. By generalizing what behaviors or approaches work for those who are most successful — typically the top 10 percent — strategies are developed that may help the general population achieve certain goals.

"Positive deviance has been used in diverse health-related interventions, but has not previously been used in weight-loss interventions," Kraschnewski said.

For AchieveTogether, users were educated on 36 weight-loss behaviors identified in a previous study of people who maintained a weight loss of at least 30 pounds. These behaviors were evaluated by a physician for safety.

Participants logged in to the site at least once a week and were asked to record their weight, height and frequency of using the weight loss practices. They were matched to three role models closest to them for gender, age and target body weight and could then view their role model's strategies for weight loss.

Participants developed a weight-loss plan by choosing as many of the strategies as they wanted and were encouraged to choose at least one.

"At each log in, participants received tailored feedback to help them choose which practices to keep doing or learned ways to adapt them based on their own activity," Kraschnewski said.

Users of the AchieveTogether website lost about 4.5 pounds more weight than the control group. Results were published in American Journal of Preventative Medicine.

"While this is modest weight loss, it is in the range we have seen for other Internet-based weight loss programs, including those with more human contact," Kraschnewski said. "Because AchieveTogether, or a similar program, can be offered free, it could increase physician referrals for weight management and be a cost effective way to promote weight loss on a public health scale."

Future research will look at how to increase engagement with the website, examine individual characteristics associated with different outcomes and explore best how to use the experience of a diverse group to build a more complete program of weight loss interventions and management.

Other researchers on the project were Heather L. Stuckey, D. Ed., Liza S. Rovniak, Ph.D., M.P.H., Jennifer M. Poger, M.Ed., and Christopher Sciamanna, M.D., M.P.H., Department of Medicine, Penn State College of Medicine; Erik B. Lehman, M.S., and Donna K. Kephart, M.H.A., Department of Public Health Sciences, Penn State College of Medicine; Madhu Reddy, Ph.D., College of Information Sciences and Technology, Penn State; and Elliot J. Coups, Ph.D., Department of Health Education and Behavioral Science, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School.

This study was funded under a grant with the Pennsylvania Department of Health using Tobacco CURE Funds and by the National Institutes of Health.

study carried out in Spain reveals that certain healthy habits, like eating more than four times a day or not eating too fast, are associated with lower body fat levels independently of exercise habits during free time.

The key to preventing obesity is in keeping up healthy eating habits and this is not a new concept. But, a new study headed by the Institute of Food Science and Technology and Nutrition (ICTAN) of the Spanish National Research Council (CSIC) goes one step further.

The study shows that certain healthy habits, like eating more than four scheduled meals a day or not eating too fast, are associated with lower body fat levels independently of exercise habits during free time.

Data on fat levels were obtained by taking the sum of six skin folds and the waist circumference of 1,978 adolescents (1,017 girls) between the ages of 13 and 18 years from five Spanish cities (Granada, Madrid, Murcia, Santander and Zaragoza). The role that physical activity during free time plays on fat levels was also assessed.

"To clarify the effects of dietary habits on obesity it is vital to study them along with other lifestyle habits such as physical activity," explained Sonia Gómez Martínez, lead author of the study and researcher at the ICTAN's department of Metabolism and Nutrition.

The young men were taller, weighed more, had a larger waist circumference, and ate faster during meals. However, according to the study published in the Journal of Adolescent Health, their accumulated fat rate was lower.

Furthermore, the authors observed that eating breakfast on a daily basis is especially beneficial in the case of young men who do not do any exercise since those who skipped this meal showed higher body fat values.

Gómez Martínez stated that "the results obtained have shown that one in every four girls and one in every three boys in Spain are overweight or obese." However, only 18.5% of the boys did not do some form of sport as opposed to 48.5% of the girls.

Special requirements

Sexual maturity and the increase in size and weight determine the nutritional needs of adolescents, who grow by approximately 20% of their adult height and 50% of their muscle and bone mass during puberty.

Such processes require a high amount of energy and nutrients and so the diet should be designed to meet such requirements. During adolescence, the three most important minerals are calcium, iron and zinc.

Whereas calcium is essential for bone growth, iron is involved in haematologic tissue (red blood cells) and muscle tissue growth, and zinc plays a part is bone and muscle growth. It is also linked to hair and nail growth.

Dietary recommendations for adolescents include drinking three or four glasses of milk or yoghurt for calcium, vitamin D and riboflavin; five or more portions of fruit and vegetables; two portions of lean protein foods; six to twelve portions of cereal, pasta, rice and potatoes; and eat foods rich in fat and sugar in moderation.

Overweight women may never escape the painful stigma of obesity – even after they have shed the pounds, new research suggests.

The study, by the University of Hawaii at Mānoa, The University of Manchester, and Monash University, examined whether anti-fat prejudice against women persisted even after they had lost significant weight and were now thin.

The researchers asked young men and women to read vignettes describing a woman who had either lost weight (70 pounds/32 kilograms) or had remained weight stable, and who was either currently obese or currently thin. Participants were then asked their opinions about this woman on a number of attributes, such as how attractive they found her, and their overall dislike for fat people.

The team found that participants in the study – published in the journal Obesity – expressed greater bias against obese people after reading about women who had lost weight than after reading about women who had remained weight stable, regardless of whether the weight-stable woman was thin or obese.

"We were surprised to find that currently thin women were viewed differently depending on their weight history," said Dr Janet Latner, study lead at the University of Hawaii at Mānoa, US. "Those who had been obese in the past were perceived as less attractive than those who had always been thin, despite having identical height and weight."

One of the more disturbing findings from the study, the researchers noted, was that negative attitudes towards obese people increase when participants are falsely told that body weight is easily controllable.

Co-author, Dr Kerry O'Brien, from the University of Manchester's School of Psychological Sciences and Monash University in Melbourne, Australia, said: "The message we often hear from society is that weight is highly controllable, but the best science in the obesity field at the moment suggests that one's physiology and genetics, as well as the food environment, are the really big players in one's weight status and weight-loss.

"Weight status actually appears rather uncontrollable, regardless of one's willpower, knowledge, and dedication. Yet many people who are perceived as 'fat' are struggling in vain to lose weight in order to escape this painful social stigma. We need to rethink our approaches to, and views of, weight and obesity."

The findings, say the authors, demonstrate that residual obesity stigma persists against individuals who have ever been obese, even when they have lost substantial amounts of weight. Obesity stigma is so powerful and enduring that it appears to even outlast the obesity itself.

Dr Latner added: "Descriptions of weight loss, such as those often promoted on television, may significantly worsen obesity stigma. Believing that obese people can easily lose weight may make individuals blame and dislike obese people more.

"The findings demonstrate that residual obesity stigma persists against individuals who have ever been obese, even when they have lost substantial amounts of weight. Obesity stigma is so powerful and enduring that it may even outlast the obesity itself. Given the great number of people who may be negatively affected by this prejudice, obesity discrimination clearly needs to be reduced on a societal level."

For years the Mediterranean diet has been associated with a lesser chance of illness and increased well-being. A new study has now linked it to mental and physical health too.

The Mediterranean diet, which is characterised by the consumption of fruit, vegetables, pulses (beans, peas, chickpeas and lentils etc.) , fish, olive oil and nuts, has been proven to be beneficial to the health in terms of a lesser chance of chronic illness and a lower mortality rate.

A new study headed by the University of Las Palmas de Gran Canaria and the University of Navarra took the next step and analysed the influence of the Mediterranean diet on the quality of life of a sample of more than 11,000 university students over a period of four years.

"The progressive aging of the population in developed countries makes it even more interesting to find out those factors that can increase quality of life and the health of the population," as explained by Patricia Henríquez Sánchez, researcher at the centre in the Canary Islands and lead author of the study.

Dietary intake data was taken at the beginning of the study and self-perceived quality of life was measured after the four year monitoring period. In order to ascertain whether the Mediterranean diet was followed, consumption of vegetables, pulses, fruit, nuts, cereals and fish was positively valued whereas consumption of meat, diary products and alcohol was negatively valued.

Published in the European Journal of Clinical Nutrition, the results reveal that those who stick more to the Mediterranean diet score higher on the quality of life questionnaire in terms of physical and mental well-being. This link is even stronger in terms of physical quality of life.

The Mediterranean Pyramid

Henríquez states that "the Mediterranean diet is an important factor associated with better quality of life and can be considered as a healthy food model." Its food pyramid combines food to be eaten daily, weekly and occasionally.

Main meals should never lack three basic elements: cereals, fruit and vegetables and dairy products. Furthermore, it must include a daily intake of 1.5 and 2 litres of water. Olive oil constitutes the main source of fat for its nutritional quality and moderate consumption of wine and other fermented beverages is recommended.

Furthermore, fish, lean meat and eggs are sources of high quality animal protein. Fish and seafood are also sources of healthy fats.

At the top of the pyramid are sugar, sweets, cakes, pastries and sweetened beverages that should be consumed occasionally and in small amounts.

 Calcium supplements might increase the risk of having a heart attack, and should be "taken with caution," concludes research published in the online issue of the journal Heart.

Furthermore, boosting overall calcium intake from dietary sources confers no significant advantage in terms of staving off heart disease and stroke, the findings indicate.

Previous research has linked higher calcium intake with a lowered risk of high blood pressure, obesity, and type 2 diabetes, all of which are risk factors for heart disease and stroke.

And calcium supplements are commonly recommended to elderly people and women who have gone through the menopause to prevent bone thinning.

The authors base their findings on almost 24,000 participants of one of the German arms of the European Prospective Investigation into Cancer and Nutrition (EPIC) study in Heidelberg.

All the participants were aged between 35 and 64 when they joined the study in 1994-8.

Normal diet for the preceding 12 months was assessed using food frequency questionnaires and they were quizzed about whether they regularly took vitamin or mineral supplements.

Their health was tracked for an average of 11 years, during which time 354 heart attacks, 260 strokes, and 267 associated deaths occurred.

After taking account of factors likely to influence the results, those whose diets included a moderate amount (820 mg daily) of calcium from all sources, including supplements, had a 31% lower risk of having a heart attack than those in the bottom 25% of calcium intake.

But those with an intake of more than 1100 mg daily did not have a significantly lower risk. There was no evidence that any level of calcium intake either protected against or increased the risk of stroke, which backs up the findings of other research, say the authors.

But when the analysis looked at vitamin/mineral supplements, it found that those who took calcium supplements regularly were 86% more likely to have a heart attack than those who didn't use any supplements.

And this risk increased further among those who used only calcium supplements. They were more than twice as likely to have a heart attack as those who didn't take any supplements.

The authors conclude: "This study suggests that increasing calcium intake from diet might not confer significant cardiovascular benefits, while calcium supplements, which might raise [heart attack] risk, should be taken with caution."

In an accompanying editorial, Professors Ian Reid and Mark Bolland from the Faculty of Medical and Health Science at the University of Auckland in New Zealand, say that the safety of calcium supplements "is now coming under increasing scrutiny."

They point to previous research, showing a link between these supplements and kidney stones, and gut and abdominal symptoms, and note that while trial evidence suggests that calcium supplements cut levels of cardiovascular risk factors, this doesn't actually translate into fewer heart attacks and strokes.

They also suggest that many women taking calcium supplements to ward off brittle bones are already healthier than those who don't, and that the overall protective effect is modest — in the order of just 10%.

The evidence that dietary calcium is helpful while calcium supplements are not can be explained by the fact that dietary calcium is taken in small amounts, spread throughout the day, so is absorbed slowly, they say.

Supplements, on the other hand, cause calcium levels in the blood to soar above the normal range, and it is this flooding effect which might ultimately be harmful, they suggest.

"Calcium supplements have been widely embraced by doctors and the public, on the grounds that they are a natural and therefore safe way of preventing osteoporotic fractures," they write.

"It is now becoming clear that taking this micronutrient in one or two daily [doses] is not natural, in that it does not reproduce the same metabolic effects as calcium in food," they say.

Given that it is neither safe nor effective, boosting calcium intake from supplements should be discouraged, they contend.

And they conclude: "We should return to seeing calcium as an important component of a balanced diet, and not as a low cost panacea to the universal problem of postmenopausal bone loss."