Effect of Low-Carbohydrate vs Low-Fat Diet Intervention on Visceral Fat in a 12-Month Randomized Controlled Trial

Dietary restriction via a healthy low-fat (HLF) diet or a healthy low-carbohydrate (HLC) diet vary in their effects on adiposity and metabolism. The HLC diet, but not HLF diet, may preferentially reduce visceral adipose tissue (VAT), the major adipose tissue contributing to metabolic deregulation. In a 12-month weight loss trial, DIETFITS (Diet Intervention Examining The Factors Interacting with Treatment Success), we compared VAT loss between HLF and HLC diets by randomizing adults to either diet. VAT was measured using dual-energy x-ray absorptiometry. Linear mixed models analyzed associations between diet and VAT. Among 449 participants (60% women; mean age 39 years), VAT loss was significantly greater for those eating the HLC diet compared to the HLF diet at 6 months [10.6cm ² ; 95% confidence interval (CI): 5,16.2] and 12 months (6.3cm ² ; 95% CI: 0.6,12). Preferential VAT loss was greater in participants eating the HLC diet at 6 months only. Men experienced greater HLC diet-induced VAT loss than women. Insulin secretion status did not modify VAT loss. HLC diet reduced metabolically harmful VAT, particularly during the first 6 months of diet. Lowering VAT has the potential to reduce risk for cardiometabolic disease. Sex differences should be considered in designing effective dietary interventions.