EFFECTS OF DIET AND PHYSICAL ACTIVITY INTERVENTIONS

Date Posted: October 12, 2010
Authors: Goodpaster BH, DeLany JP, Otto AD, et al.
Citation: JAMA 2010;Oct 9:[Epub ahead of print].



Question:
What are the effects of weight loss and physical activity intervention on the adverse health risks of severe obesity?

Methods:
A single-blind randomized trial was conducted from February 2007 through April 2010 at the University of Pittsburgh. Participants were 130 (37% African American) severely obese (class II or III) adult participants without diabetes recruited from the community. Patients were provided a 1-year intensive lifestyle intervention consisting of diet and physical activity. One group (initial physical activity) was randomized to diet and physical activity for the entire 12 months; the other group (delayed physical activity) had the identical dietary intervention, but with physical activity delayed for 6 months. Primary outcome was change in weight. Secondary outcomes were additional components comprising cardiometabolic risk, including waist circumference, abdominal adipose tissue, and hepatic fat content.

Results:
There was no difference between groups for: mean age 46 years, 10% men, mean body mass index 43.5 kg/m2, and 75% had class III obesity. Of 130 participants randomized, 101 (78%) completed the 12-month follow-up assessments. Although both intervention groups lost a significant amount of weight at 6 months, the initial-activity group lost significantly more weight in the first 6 months compared with the delayed-activity group (10.9 kg, 95% confidence interval [CI], 9.1-12.7 vs. 8.2 kg, 95% CI, 6.4-9.9; p = 0.02 for group × time interaction). Weight loss at 12 months, however, was similar in the two groups (12.1 kg, 95% CI, 10.0-14.2 vs. 9.9 kg, 95% CI, 8.0-11.7; p = 0.25 for group × time interaction). Waist circumference, visceral abdominal fat, hepatic fat content, blood pressure, and insulin resistance were all reduced in both groups. The addition of physical activity promoted greater reductions in waist circumference and hepatic fat content.

Conclusions:
Among patients with severe obesity, a lifestyle intervention involving diet combined with initial or delayed initiation of physical activity resulted in clinically significant weight loss and favorable changes in cardiometabolic risk factors.

Perspective:
The findings are intuitive. Experience in our center is that patients who commit to both exercise and diet do better with weight loss and metabolic parameters, at least in part because of improved diet compliance in those who exercise