# Modulation of the Kynurenine Pathway in Obese Mexican Navy Women Following a Structured Weight Loss Program: A Pre–Post-Intervention Study

## TL;DR

A 12-week weight loss program in obese Mexican Navy women reduced body weight and improved metabolic and psychological markers, including changes in the kynurenine pathway.

## Contribution

This study explores how a structured weight loss program modulates the kynurenine pathway in obese women, linking metabolic and psychological improvements.

## Key findings

- The weight loss program significantly reduced body weight, BMI, fat mass, fasting insulin, and C-reactive protein.
- Serum concentrations of tryptophan, kynurenine, and kynurenic acid decreased following the intervention.
- Higher KYNA-related ratios were inversely associated with depressive symptoms.

## Abstract

Background: Obesity is characterized by chronic low-grade inflammation and metabolic disturbances, including an altered tryptophan (Trp) catabolism through the kynurenine pathway (KP). Since the KP is closely linked to immune activity, energy metabolism, and hepatic function, modulating its flux through lifestyle interventions has gained interest as a potential therapeutic strategy. Objective: This exploratory study aimed to investigate the impact of a structured 12-week weight loss program (WLP) on serum KP metabolites in a sample of Mexican women with obesity. Methods: This study involved a pre–post-intervention design conducted in twenty-four women with clinically diagnosed obesity from the Mexican Navy who underwent a structured 12-week weight loss program combining a hypocaloric diet with moderate-intensity aerobic exercise; no control group was included. Anthropometric parameters, serum biochemistry, and circulating levels of Trp, kynurenine (KYN), kynurenic acid (KYNA), and 3-hydroxykynurenine (3-HK) were assessed before and after intervention. Psychological assessments of anxiety and depression were also conducted in a subset of participants. Results: The WLP significantly reduced body weight, BMI, fat mass, fasting insulin, and C-reactive protein levels. Serum concentrations of Trp, KYN, and KYNA decreased, while 3-HK showed a non-significant upward trend. Enzymatic indexes revealed a significant increase in the 3-HK/KYN ratio and a decrease in the KYNA/3-HK ratio, suggesting a shift toward kynurenine monooxygenase (KMO) branch. Notably, higher KYNA-related ratios were inversely associated with depressive symptoms. Conclusions: These findings position the KP as a responsive metabolic interface potentially linking improvements in body composition, liver function, and psychological status during structured weight loss efforts.