NEW YORK—Adopting a relatively active lifestyle, by limiting the amount of time spent watching TV and having a moderate level of activity, could substantially lower the risk of becoming obese or developing type 2 diabetes, according to an article in the April 9 issue of the Journal of the American Medical Association (JAMA), a theme issue on obesity.

Lead author Frank B. Hu, MD, PhD, of the Harvard School of Public Health and Brigham and Women's Hospital, Boston, Mass, presented the findings of the study today at a JAMA media briefing on obesity at the New York Academy of Sciences.

According to a survey conducted in the United States in 1997, an adult male spent approximately 29 hours per week watching TV and an adult female spent 34 hours per week watching TV. Compared with other sedentary activities including sewing, playing board games, reading, writing, and driving a car, TV watching results in a lower metabolic rate, according to information in the article. Prolonged TV watching is also associated with obesity in children. Current public health campaigns to reduce obesity and type 2 diabetes have largely focused on increasing exercise, but have paid little attention to the reduction of sedentary behaviors.

Dr Hu and colleagues examined the relationship between various sedentary behaviors including prolonged TV watching and the risk of obesity and type 2 diabetes in adult women.

The study included 50 277 women who participated in the Nurses' Health Study, which was conducted from 1992 to 1998 among women from 11 states. This study included women with body mass indexes (BMI, kg/meters squared, a person's weight in kilograms divided by height in meters squared) of less than 30 (a BMI of ≥30 indicates obesity; a 5'4" women would have a BMI of 30 if she weighed 174 lbs.)

The study also included women who did not have a diagnosed cardiovascular disease, diabetes, or cancer and answered questions on physical activity and sedentary behavior at the start of the study. The diabetes analysis included 68 497 women who were free of diabetes, cardiovascular disease, or cancer at the beginning of the study.

Over the 6 years of follow-up, 3757 (7.5%) of the 50 277 women who had a BMI of less than 30 in 1992 became obese (BMI of ≥30). The researchers also diagnosed 1515 new cases of type 2 diabetes. They found that time spent watching TV was positively associated with risk of obesity and type 2 diabetes.

In further analysis that adjusted for age, smoking, exercise levels, and diet, each 2 hours per day increment of TV watching was associated with a 23% increase in obesity and a 14% increase in the risk for diabetes. Each additional 2 hours per day increment of sitting at work or away from home or driving was associated with a 5% increase in obesity and a 7% increase in diabetes.

In contrast, standing or walking around at home (2 hours a day) was associated with a 9% reduction in obesity and a 12% reduction in diabetes. Each hour per day of brisk walking was associated with a 24% reduction in obesity and a 34% reduction of diabetes. The researchers estimated that 30% of new cases of obesity and 43% of new cases of diabetes could have been prevented by adopting a relatively active lifestyle of less than 10 hours per week of TV watching and 30 minutes or more per day of brisk walking.

The researchers describe 3 ways that TV watching increases the risk for obesity and diabetes. "First, TV watching typically displaces physical activity and thus reduces energy expenditure," the authors write. "Second, TV watching results in increased food and total energy intake because individuals tend to eat while watching TV despite their low physical activity levels. Also, participants who spent more time watching TV tended to follow an unhealthy eating pattern," write the researchers. "Such an eating pattern is directly related to commercial advertisements and food cues appearing on TV and has been associated with risk of obesity and diabetes." Finally, the researchers write that " ... TV viewing results in lower energy expenditure compared with other sedentary activities like sewing, reading, writing, and driving a car."

NEW YORK—After 2 years, participants in a structured commercial weight loss program maintained a modest weight loss averaging about 6 pounds, while those trying to lose weight on their own had an average weight loss of less than a pound, according to an article published in the April 9 issue of the Journal of the American Medical Association (JAMA), a theme issue on obesity.

Lead author Stanley Heshka, PhD, of the New York Obesity Research Center, St Luke's/Roosevelt Hospital and Columbia University, New York, presented the findings of the study today at a JAMA media briefing on obesity at the New York Academy of Sciences.

Formal diet and exercise programs provide weight loss treatment to approximately 13% of women and 5% of men attempting to lose weight, according to background information in the article. However, obese participants in diet and exercise programs rarely achieve a weight in the normal range, and because weight lost is often regained there is a perception that nothing is accomplished by participation in such programs. Nevertheless, numerous studies have documented improvements in indicators of health with modest weight loss, which, if maintained over several years, may be clinically significant. Although commercial weight loss programs provide treatment to millions of clients, their efficacy has not been evaluated in rigorous long-term trials.

Heshka and colleagues conducted a study to compare weight loss and health benefits achieved and maintained through self-help weight loss vs the largest provider of commercial weight loss services in the United States (Weight Watchers). The study included overweight and obese men (n=65) and women (n=358) aged 18 to 65 years with a body mass index (BMI) of between 27 and 40. Body mass index is weight in kilograms divided by the height in meters squared. A 5'4" woman with a BMI of 27 would weigh 157 lbs.; a 5'4" woman with a BMI of 40 would weigh 232 lbs.

The study consisted of a 2-year, multicenter randomized clinical trial with clinic visits at 12, 26, 52, 78, and 104 weeks conducted at 6 academic research centers in the United States between January 1998 and January 2001. The participants were randomly assigned to either a self-help condition (n=212) consisting of two 20-minute counseling sessions with a nutritionist and provision of self-help resources or to a commercial weight loss program (n=211) consisting of a food plan, an activity plan, and a behavior modification plan, delivered at weekly meetings.

At 2 years, 150 participants (71%) in the commercial group and 159 (75%) in the self-help group completed the study. "The self-help group was able to lose and maintain approximately [2.86 to 3.08 lbs] for the first year, after which weight tended to increase until it returned to baseline [the weight at the beginning of the trial] at 2 years. The commercial group maintained a weight loss of [9.46 to 11 lbs] at the end of the first year and was [5.94 to 6.6 lbs] lower than baseline weight at the end of the second year," the researchers write. "Waist circumference, an independent cardiovascular risk factor, was also reduced in the commercial group by about [1.77 inches] at 1 year and [.98 inches] at 2 years." Body mass index also decreased more in the commercial group. Changes in blood pressure, cholesterol, glucose, and insulin levels were related to changes in weight in both groups, but between-group differences in biological parameters were mainly nonsignificant by year 2.

The authors add that it should be emphasized that this study reports on a particular commercial program with many unique aspects. "Our results should not be taken as representative of all commercial programs, many of which use other interventions, such as proprietary liquid formulas or diets that are not balanced."

NEW YORK—A new meta-analysis of studies of low-carbohydrate diets finds there is insufficient evidence to make recommendations for or against the use of these diets, according to an article published in the April 9 issue of the Journal of the American Medical Association (JAMA), a theme issue on obesity.

Lead author Dena M. Bravata, MD, MS, from Stanford University School of Medicine, Stanford, Calif, presented the findings of the study today at a JAMA media briefing on obesity at the New York Academy of Sciences.

Between 1960 and 2000, the prevalence of obesity among adults aged 20 years to 74 years in the United States increased from 13.4% to 30.9%, according to background information provided in the article. Results from the 1998 Behavioral Risk Factor Surveillance Survey indicate that roughly one third of US adults were trying to lose weight at that time, and another third were trying to maintain weight. The authors write, "Recently, low-carbohydrate diets have resurged in popularity as a means of rapid weight loss, yet their long-term efficacy and safety remain poorly understood." Over the past 5 years, 3 books on low-carbohydrate diets collectively sold millions of copies in the United States. Numerous professional organizations, including the American Dietetic Association and the American Heart Association have cautioned against the use of low-carbohydrate diets. There are concerns that these diets may have serious medical consequences.

Dr Bravata and colleagues conducted a search of the medical literature for studies published between 1966 and February 2003 with keywords including low carbohydrate and diet. The authors analyzed the data to synthesize the literature on low-carbohydrate diets to evaluate changes in weight, serum lipids (cholesterol), fasting serum glucose, fasting serum insulin, and blood pressure among adults using low-carbohydrate diets as outpatients.

The authors found 107 articles reporting data on 3268 participants, of whom 663 received lower carbohydrate diets (60 g/d or less of carbohydrates)—and only 71 had the lowest-carbohydrate diets—20 g/d or less of carbohydrates (the recommended threshold for some of the most popular diets).

"No study evaluated diets of 60 g/d or less of carbohydrates in participants with a mean age older than 53 years. Only 5 studies evaluated these diets for more than 90 days," the authors report. "Among obese patients, weight loss was associated with longer diet duration, restriction of calorie intake, but not with reduced carbohydrate content. Low-carbohydrate diets had no significant adverse effect on serum lipid, fasting serum glucose, and fasting serum insulin levels, or blood pressure."

"Our quantitative synthesis ... on the efficacy and safety of low-carbohydrate diets suggests that there is insufficient evidence to make recommendations for or against the use of these diets. Despite the large number of Americans who have apparently adopted this approach to weight loss and/or weight maintenance, we know little of its effects or consequences," the authors write. "We found insufficient evidence to conclude that lower-carbohydrate content is independently associated with greater weight loss compared with higher-carbohydrate content. We did find, however, that diets that restricted calorie intake and were longer in duration were associated with weight loss. Given the limited evidence in this review, when lower-carbohydrate diets result in weight loss, it also is likely due to the restriction of calorie intake and longer duration rather than carbohydrate intake."

NEW YORK—With the number of children and teenagers who are overweight increasing at an alarming rate, and effective and lasting weight loss difficult to achieve, preventing obesity will play an important role in decreasing its prevalence, according to an editorial published in the April 9 issue of the Journal of the American Medical Association (JAMA), a theme issue on obesity.

Jack A. Yanovski, MD, PhD, Head of the Unit on Growth and Obesity, National Institute of Child Health and Human Development, and Susan Z. Yanovski, MD, Director, Obesity and Eating Disorders Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Md, write about the treatment of pediatric obesity.

Susan Z. Yanovski, MD, presented the editorial today at a JAMA media briefing on obesity at the New York Academy of Sciences.

"The proportion of children and adolescents who are overweight, defined as a body mass index exceeding the 95th percentile for age and sex based on norms from the 1960s, has tripled in the past 3 decades. This dramatic increase in overweight has not been confined to US children and adolescents; pediatric overweight is also increasing in other countries," the authors write. They add that greater body weight has been found to predispose children and adolescents to many of the medical complications of obesity found in adults, including hypertension, type 2 diabetes, steatohepatitis (liver disorder), sleep apnea, and to problems unique to childhood and adolescence, including accelerated skeletal development and certain orthopedic disorders.

"Overweight during childhood and adolescence also appears to be an important independent predictor of health risks and mortality in later life, even when adult weight is taken into account. Thus, it seems clear that one of the most compelling medical challenges of the 21st century is to develop effective strategies to prevent and treat pediatric obesity," they write.

"As the number of children and adolescents with severe obesity and [accompanying] medical problems increases, the inclination for clinicians to consider intensive treatments, including pharmacotherapy and surgery, becomes greater. Given the many ways in which children and adolescents differ from adults, physicians must not conclude that treatments found safe and effective in adults will have similar safety and effectiveness in pediatric populations."

The authors note that while it is appropriate to consider intensive treatments in severely obese adolescents with multiple illnesses, such treatments should be regarded as investigational at this time and should be performed as part of a closely monitored research study. "Clinicians should consider referring severely obese children and adolescents to experienced, specialized pediatric obesity centers, so that intensive treatment can be performed by a team of professionals that may include physicians, dietitians, behaviorists, and exercise specialists with expertise in pediatric and adolescent medicine."

"Rapid advances in basic and clinical science are elucidating the complex genetic, psychosocial, metabolic, and environmental factors that contribute to the development of obesity and its [other] conditions. This research will lead to improved methods for prevention and treatment of obesity in the years ahead. Researchers should be encouraged to include children and adolescents in clinical research studies of obesity prevention and treatment, so that the risks and benefits from therapeutic advances can be established in pediatric populations."

The April issue of the Archives of Surgery is devoted to a review of current trends in the surgical treatment of morbid obesity. The costs associated with the treatment of obesity are substantial, with billions of dollars spent yearly in the United States on weight reduction, with a large portion spent on treatment of health complications resulting from obesity.

An estimated 64.5% of American adults (more than 120 million people) are overweight or obese, an increase from 45% in 1960. The incidence of juvenile obesity has doubled in the last 20 years, affecting an estimated 15% of children between 6 and 19 years old. Obesity has been predicted to surpass smoking as the leading cause of preventable deaths in the United States.

In 1991, the second National Institutes of Health Consensus Conference concluded that surgery should be offered to severely obese patients who do not respond to other treatments to reduce their weight. Since then, 2 procedures have become standard in surgically treating obesity. The Roux-en-Y gastric bypass procedure (where the stomach is reduced to a small [about 1 ounce] pouch and much of the small intestine is bypassed) and adjustable gastric banding (where the stomach is reduced by placing a band around the top portion of the stomach that can be tightened or loosened) are the 2 most common surgical procedures for treating obesity.

ARTICLES FROM THE APRIL ISSUE OF THE ARCHIVES OF SURGERY:

HISTORICAL OVERVIEW

Kenneth G. MacDonald, Jr, MD, of the Brody School of Medicine at East Carolina University, Greenville, NC, gives an overview of the growing epidemic of obesity and the history of some of the surgical remedies that have been used to treat obesity. Dr MacDonald defines obesity, names its associated complications such as diabetes mellitus and hypertension, and discusses its prevalence and some of the surgical procedures available for treating obesity including jejunoileal bypass, modern malabsorptive procedures, and gastric restrictive procedures.

SURGICAL INNOVATIONS

Edward E. Mason, MD, PhD, of the University of Iowa College of Medicine, Iowa City, discusses surgical techniques used in weight loss surgeries of the past and outlines some innovations in surgical weight loss operations that could improve its safety and success in the future.

LAPAROSCOPIC PROCEDURES

Daniel R. Cottam, MD, of University of Pittsburgh, Pittsburgh, Pa, and colleagues discuss the past and future of laparoscopic procedures for treating obesity. Laparoscopic banding and Roux-En-Y procedures are detailed.

GASTRIC BANDING

Paul E. O'Brien, MD, FRACD, of Monash University, Melbourne, Australia, and colleagues summarize surgical techniques, complications, and successes associated with laparoscopic adjustable gastric banding, a procedure that reduces the stomach to a small pouch using band placed around the top of the stomach. Laparoscopic adjustable gastric banding has been in clinical use for 8 years.

COSTS OF OBESITY & QUALITY OF LIFE

Edward H. Livingston, MD, of Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, Calif, and Aaron S. Fink, MD, of Veterans Affairs Medical Center and Emory University, Atlanta, Ga, talk about the costs associated with surgical procedures to reduce weight and quality of life issues that patients must address after surgery. Recent estimates are that $70 billion or 9.4% of all health care costs are attributable to treating obesity and obesity-related complications, according to the article.

GHRELIN

David E. Cummings, MD, and Michael H. Shannon, MD, of University of Washington, Veterans Affairs Puget Sound Health Care System, Seattle give a brief overview of the role of the hormone ghrelin in regulating appetite and body weight. Ghrelin is an appetite-stimulating hormone that holds promise as a potential target for treating obesity.

PROLONGED TV WATCHING LINKED TO OBESITY AND DIABETES