To determine the efficacy of a weight loss and physical activity intervention on the adverse health risks of severe obesity.

The prevalence of severe obesity is increasing markedly, as is the prevalence of comorbid conditions such as hypertension and type 2 diabetes mellitus; however, apart from bariatric surgery and pharmacotherapy, few clinical trials have evaluated the treatment of severe obesity.

Objective

To determine the efficacy of a weight loss and physical activity intervention on the adverse health risks of severe obesity.

Design, setting, and participants

A single-blind randomised trial was conducted from February 2007 through to 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.

Interventions

One year of intensive lifestyle intervention consisting of diet and physical activity. One group (initial physical activity) was randomised to diet and physical activity for 12 months; the other group (delayed physical activity) had the identical dietary intervention, but with physical activity delayed for six months.

Main outcome measures

Changes in weight. Secondary outcomes were additional components comprising cardio-metabolic risk, including waist circumference, abdominal adipose tissue, and hepatic fat content.

Results

Of 130 participants randomised, 101 (78%) completed the 12-month follow-up assessments. Although both intervention groups lost a significant amount of weight at six months, the initial activity group lost significantly more weight in the first six 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 =.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 =.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.

In this case study, you will need to critically comment on the strength of the evidence presented in this study and how you might apply it to the local population.