Clinical ScienceAdipose triglyceride lipase and hormone-sensitive lipase protein expression in subcutaneous adipose tissue is decreased after an isoenergetic low-fat high-complex carbohydrate diet in the metabolic syndrome

The objective was to determine the contribution of dietary fat quantity and composition to lipolysis and lipolytic gene expression in humans in relation to obesity, insulin resistance, and the metabolic syndrome (MetS). Men and women with the MetS were randomly assigned to one of four isoenergetic diets: a high-fat saturated fat diet (n = 10), a high-fat monounsaturated fat diet (n = 7), and two low-fat high-complex carbohydrate (LFHCC) diets, one supplemented with 1.24 g/day long-chain n-3 PUFA (LFHCC: n = 7, LFHCCn-3: n = 8). Subcutaneous adipose tissue biopsies were taken before and after the 12-week dietary intervention period. ATGL and HSL mRNA and protein expression was determined. Whole body rate of appearance of free fatty acids (RaFFA) was determined by intravenous infusion of [2H2]-palmitate in a subgroup of men (n = 20). Adipose tissue ATGL and HSL mRNA and protein expression was not affected by alterations in dietary fat composition. Pooled analysis comparing the low- and high-fat diets showed that ATGL and HSL protein expression was significantly reduced after the LFHCC diets (P = .04), irrespective of long-chain n-3 PUFA. Moreover, LFHCC diets lowered fasting insulin, HOMAIR, and (LDL)-cholesterol concentrations (P ≤ .05). Changes in ATGL and HSL protein expression was positively associated with changes in whole body RaFFA (P < .03). The low-fat high-complex carbohydrate diets reduced ATGL and HSL protein expression and significantly improved circulating lipids and insulin sensitivity. Under isoenergetic conditions, dietary fat quantity, rather than composition, may be most important for modulating subcutaneous adipose tissue ATGL and HSL protein expression.