Interpreting weight losses from lifestyle modification trials: using categorical data.

Although studies in obese subjects using weight loss medications typically report mean and categorical weight loss, results from diet and exercise intervention trials typically only report mean weight change from baseline along with a level of significance. These data alone do not give clinicians or administrators the data needed to determine the probability that an individual will achieve clinically relevant weight loss. Thus, it is difficult to decide which patients, employees or health plan enrollee would benefit from the type and level of support used in a clinical trial. Our goal was to assess what fraction of subjects enrolled in lifestyle modification interventions achieved clinically significant weight loss. Thus, we requested categorical weight loss data from several investigators who had published results from studies involving either a high- or low-intensity lifestyle modification intervention arm. These categorical data indicate that a substantial fraction of subjects in each lifestyle modification intervention achieved clinically meaningful weight loss, even when the average weight loss is modest.