To the Editor: Dr Lee and colleagues1 examined the relationship between physical activity and weight gain prevention. The study concluded that physical activity is inversely related to weight gain in women of normal weight, but not in women who are overweight. However, this conclusion may be flawed.
It seems that the authors did not take into account that normal weight and overweight individuals spend different amounts of time sitting vs standing. A pilot study suggested that obese people sit 2 hours longer, on average, than lean people.2 This difference may enable normal weight women to burn up to an extra 350 calories a day,2 a sum likely large enough to account for the study's findings.
Kwatra SG. Physical Activity and Preventing Weight Gain in Women. JAMA. 2010;303(24):2475-2476. doi:10.1001/jama.2010.825