The obesity epidemic shows no signs of abating. There is an urgent need to push back against the environmental forces that are producing gradual weight gain in the population. Using data from national surveys, we estimate that affecting energy balance by 100 kilocalories per day (by a combination of reductions in energy intake and increases in physical activity) could prevent weight gain in most of the population. This can be achieved by small changes in behavior, such as 15 minutes per day of walking or eating a few less bites at each meal. Having a specific behavioral target for the prevention of weight gain may be key to arresting the obesity epidemic.

The current epidemic of obesity is caused largely by an environment that promotes excessive food intake and discourages physical activity. Although humans have evolved excellent physiological mechanisms to defend against body weight loss, they have only weak physiological mechanisms to defend against body weight gain when food is abundant. Control of portion size, consumption of a diet low in fat and energy density, and regular physical activity are behaviors that protect against obesity, but it is becoming difficult to adopt and maintain these behaviors in the current environment. Because obesity is difficult to treat, public health efforts need to be directed toward prevention.

OBJECTIVEOverweight and obese individuals are encouraged to lose 5–10% of their body weight to improve cardiovascular disease (CVD) risk, but data supporting this recommendation are limited, particularly for individuals with type 2 diabetes.RESEARCH DESIGN AND METHODSWe conducted an observational analysis of participants in the Look AHEAD (Action For Health in Diabetes) study (n = 5,145, 40.5% male, 37% from ethnic/racial minorities) and examined the association between the magnitude of weight loss and changes in CVD risk factors at 1 year and the odds of meeting predefined criteria for clinically significant improvements in risk factors in individuals with type 2 diabetes.RESULTSThe magnitude of weight loss at 1 year was strongly (P < 0.0001) associated with improvements in glycemia, blood pressure, tryiglycerides, and HDL cholesterol but not with LDL cholesterol (P = 0.79). Compared with weight-stable participants, those who lost 5 to <10% ([means ± SD] 7.25 ± 2.1 kg) of their body weight had increased odds of achieving a 0.5% point reduction in HbA1c (odds ratio 3.52 [95% CI 2.81–4.40]), a 5-mmHg decrease in diastolic blood pressure (1.48 [1.20–1.82]), a 5-mmHg decrease in systolic blood pressure (1.56 [1.27–1.91]), a 5 mg/dL increase in HDL cholesterol (1.69 [1.37–2.07]), and a 40 mg/dL decrease in triglycerides (2.20 [1.71–2.83]). The odds of clinically significant improvements in most risk factors were even greater in those who lost 10–15% of their body weight.CONCLUSIONSModest weight losses of 5 to <10% were associated with significant improvements in CVD risk factors at 1 year, but larger weight losses had greater benefits.

BACKGROUND Weight loss is recommended for overweight and obese individuals with type 2 diabetes based on short-term studies, but long-term effects on cardiovascular disease remain unknown. We examined whether intensive lifestyle intervention for weight loss decreased cardiovascular morbidity and mortality in overweight or obese adults with type 2 diabetes. METHODS We randomly assigned 5,145 overweight or obese individuals with type 2 diabetes recruited at 16 US centers to intensive lifestyle intervention (the intervention group), which promoted weight loss through decreased calorie intake and increased physical activity, or diabetes support and education (the control group). The primary outcome was the first post-randomization occurrence of a composite cardiovascular outcome (cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, or hospitalized angina) over a planned maximum follow-up of 13.5 years. RESULTS The trial was stopped early based on a futility analysis when median follow-up was 9.6 years. Weight loss was greater in the intervention group than the control group throughout (8.6% vs. 0.7% at 1 year; 6.0% vs. 3.5% at study end). Intensive lifestyle intervention also produced greater reductions in hemoglobin A1c and greater initial improvements in fitness and all cardiovascular risk factors, except LDL cholesterol. The primary outcome occurred in 403 patients in the intervention group and in 418 in the control group (1.83/100 person-years and 1.92/100 person-years, respectively; hazard ratio 0.95; 95% CI 0.83 to 1.09, p=0.505). CONCLUSION In our study, intensive lifestyle intervention focused on weight loss did not reduce cardiovascular events in overweight or obese adults with type 2 diabetes. (Funded by the Department of Health and Human Services and others; ClinicalTrials.gov number, NCT00017953.)