Obesity Incidence According to Branched-Chain Amino Acid Intake and Plant-Based Diet Index Among Brazilian Adults: A Six-Year Follow-Up of the CUME Study.

BACKGROUND

Few studies have evaluated the impact of branched-chain amino acid (BCAA) intake on the risk of obesity in adults. The results are contradictory, and the causality has not been explored. This study assessed the association between BCAA intake and obesity incidence among Brazilian adults and investigated the potential moderating role of the plant-based index (PDI) in this relationship.

METHODS

A longitudinal study was conducted between 2016 and 2022, with 3090 participants (2043 women, 1047 men; mean age 34 years) from the Cohort of Universities of Minas Gerais (CUME) Study. Data were collected through an online questionnaire. The relationship between BCAA intake and obesity incidence was assessed using crude and adjusted Cox regression models. Restricted cubic spline analysis (RCS) was used to estimate the nonlinearity. The multiplicative interaction with PDI was tested.

RESULTS

The overall incidence of obesity was 192 cases (6.21%). The incidence was 16.4/1000 person-years in females; 21.8/1000 person-years in males; and 18.3/1000 person-years total, with a mean follow-up period of 3.4 years. Compared to the first tertile, the highest intake tertiles for BCAA (HR = 1.50, 95% CI = 1.03-2.18), isoleucine (HR = 1.52, 95% CI = 1.04-2.22), and leucine (HR = 1.51, 95% CI = 1.03-2.20) were independently associated with obesity risk. BCAA intake above 16 g/day increases the risk of obesity.

CONCLUSIONS

There was a positive association between the intake of BCAA, isoleucine, and leucine with the risk of obesity. The PDI accentuated the association between BCAA intake and obesity in both the lowest and highest quintiles.