This Week in JAMA FREE

A JAMA THEME ISSUE
Edited by Phil B. Fontanarosa, MD

Based on data from Behavioral Risk Factor Surveillance System telephone surveys, 1991 to 1998, Mokdad and colleaguesArticle found that the prevalence of obesity (body mass index [BMI] ≥30 kg/m²) among US adults aged 18 years or older rose from 12.0% in 1991 to 17.9% in 1998. Increases in the prevalence of obesity occurred in all states, in both sexes, and across all age groups, races, and educational levels. In an analysis of dataArticle from 16,884 adults aged 25 years or older who participated in the Third National Health and Nutrition Examination Survey (NHANES III), Must and colleaguesArticle found that as the severity of excess weight increased from overweight (BMI, 25.0 to 29.9 kg/m²) through obesity class 3 (BMI ≥40.0 kg/m²), the prevalence of type 2 diabetes mellitus, gallbladder disease, hypertension, and osteoarthritis in both sexes and coronary heart disease in women increased. Using mortality hazard ratios associated with BMI from 6 US prospective cohort studies and 1991 population data from NHANES III, Allison and colleagues estimated the annual number of deaths attributable to obesity among US adults to be 280,184. More than 80% of deaths attributable to overweight or obesity occurred among persons with BMIs of 30 kg/m² or greater. In an editorialArticle, Koplan and Dietz call for a comprehensive national program to prevent and treat obesity.

To determine the effect of dietary composition on levels of insulin secretion, weight gain, and other cardiovascular disease (CVD) risk factors, Ludwig and colleagues analyzed data from 2909 adults, aged 18 to 30 years at enrollment and followed up for 10 years, in the Coronary Artery Risk Development in Young Adults Study. Fasting insulin levels, weight gain over 10 years, and other CVD risk factors were inversely related to levels of dietary fiber intake. In contrast, intake of fat, carbohydrate, and protein had inconsistent or weak associations with fasting insulin levels and other CVD risk factors.

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Cardiorespiratory fitness may be as important as other disease conditions and risk factors predictive of mortality. Wei and colleagues report that among 25,714 adult men enrolled between 1970 and 1993 and followed up through 1994, obese men (body mass index [BMI] ≥30 kg/m²) had a 2.6 times higher risk of cardiovascular disease (CVD) mortality and a 1.9 times higher risk of all-cause mortality compared with normal-weight men. The strongest predictor of mortality in all BMI groups was baseline CVD, but the risk of mortality associated with low cardiorespiratory fitness was comparable to the risks associated with diabetes mellitus, high cholesterol levels, hypertension, and smoking in all BMI groups, and was highest among obese men compared with overweight and normal-weight men.

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The effectiveness of strategies to prevent and treat obesity in adults and children is often limited and of short duration. Among 115 sedentary, overweight women aged 25 to 45 years randomly assigned to traditional continuous exercise (long-bout exercise, LB group), multiple short-bout exercise (SB group), or multiple short-bout exercise with home exercise equipment (SBEQ group), Jakicic and colleaguesArticle found that at 18 months, weight loss in the SBEQ group was significantly greater compared with that in the SB group and was similar to that in the LB group. Weekly duration of exercise for months 13 through 18 was significantly greater in the SBEQ group compared with the other 2 groups. In a study of 192 third- and fourth-grade children, Robinson foundArticle that the group that received a 6-month classroom curriculum to reduce television, videotape, and video game use had significant relative decreases in body mass index and other anthropometric measures of adiposity compared with the control group. The amount of television viewing and the frequency of eating meals in front of the television decreased significantly in the intervention group compared with the control group, but changes in high-fat food intake, moderate-to-vigorous physical activity, and cardiorespiratory fitness were similar.

Genetic factors that regulate energy balance and body weight.

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Gene technology applied to mice and rice helps attack, respectively, problems of obesity and malnutrition.

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Results of a preliminary controlled trial of exogenous recombinant leptin administration demonstrate a dose-response relationship with weight and fat loss in lean and obese subjects.

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Fewer than half of obese patients reportArticle being counseled by a health care professional about weight loss and only about one third of a national sample of patients report being counseled about exercise.

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For your patients: A primer on obesity.

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