Changes of Branched-Chain Amino Acids and Ectopic Fat in Response to Weight-loss Diets: the POUNDS Lost Trial

CONTEXT: Recent evidence has related circulating branch-chained amino acids (BCAAs) to ectopic fat distribution. OBJECTIVE: To investigate the associations of changes in plasma BCAAs induced by weight-loss diet interventions with hepatic fat and abdominal fat, and potential modification by different diets. DESIGN, SETTING, AND PARTICIPANTS: The current study included 184 participants from the 2-year Preventing Overweight and Using Novel Dietary Strategies (POUNDS Lost) trial with repeated measurements on plasma BCAAs, hepatic fat, and abdominal fat over 2 years. MAIN OUTCOME MEASURES: Repeated measurements of hepatic fat, abdominal fat distribution, including visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and total adipose tissue (TAT). RESULTS: Over 2 years, a decrease in total plasma BCAAs was significantly associated with improvement in hepatic density (a marker for hepatic fat; P = 0.02) and reductions in abdominal fat, including VAT, SAT, and TAT (all P < 0.05) in the main analyses. Additionally, we observed that decreases in BCAAs were associated with decreased insulin, homeostasis model assessment of insulin resistance, and triglycerides, independent of weight loss (all P < 0.05). Moreover, we found that dietary protein intake significantly modified the relation between changes in total plasma BCAAs and hepatic density at 6 months (Pinteraction = 0.01). Participants with a larger decrease in total BCAAs showed a greater increase in hepatic density when consuming a high-protein diet, compared with those with a smaller decrease or increase in total BCAAs. CONCLUSIONS: Our findings indicate that weight-loss diet-induced decrease in plasma BCAAs is associated with reductions of hepatic and abdominal fat. In addition, dietary protein intake may modify these associations.