4. Decreases in Abdominal Fat With Weight Loss

Rationale: Six acceptable RCTs on weight loss that measured waist circumferences all show that weight loss is associated with reductions in waist circumference (365, 369, 373, 375, 384, 399). Waist circumference is commonly used as a surrogate measure for abdominal visceral fat (420, 421).  Although no RCTs examined changes in visceral fat per se, one observational study (422) showed significant decreases in visceral fat with a mean weight loss of 12.9 kg (28.4 lb). 

In addition, many observational and non-RCT interventional studies have reported that weight loss caused by a variety of treatments reduces abdominal visceral fat levels (417, 423-428). Fat located in the abdominal region is associated with greater health risks than that in peripheral regions, e.g., the gluteal-femoral area (155-159, 429, 430).Many studies used the waist-to-hip ratio as the measure of abdominal fat; however, the panel considered waist circumference to be a better marker of abdominal fat content than the waist-to-hip ratio. For more information on abdominal fat, see Assessment and Classification of Overweight and Obesity.