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

Abstract

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.

Trial registration: ClinicalTrials.gov NCT00072995.

Keywords: branched-chain amino acid; ectopic fat; epidemiology; nutrition; weight-loss diet.

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Figures

Figure 1.

Hepatic density at 6-month according to tertile (T) categories of changes in total plasma BCAAs and valine in response to the high-/average-protein diet group. Data are means ± SEs values after adjustment for age, sex, ethnicity, baseline BMI, medication for controlling cholesterol, baseline values of valine or total BCAAs when appropriate, and baseline values of hepatic density. For ΔBCAAs from baseline to 6 months, median (25th, 75th) values were T1: –73.5 (–102.9, –55.9) µmol/L; T2: –15.8 (–30.2, –6.1) µmol/L; T3: 35.2 (19.3, 56.2) µmol/L, respectively. For ΔValine from baseline to 6 months, median (25th, 75th) values were T1: –42.4 (–61.0, –32.6) µmol/L; T2: –8.0 (–16.1, 0.2) µmol/L; T3: 24.0 (13.1, 31.3) µmol/L, respectively. For the average-protein group: T1, n = 30; T2, n = 22; T3, n = 30. For the high-protein group: T1, n = 23; T2, n = 32; T3, n = 23. BCAA, branched-chain amino acid; BMI, body mass index.