Effect of continuous energy restriction combined with probiotic supplementation on parameters related to homeostatic and hedonic systems of food intake in adult men living with obesity: Data from a randomized, parallel, double-blind, placebo-controlled clinical trial.

BACKGROUND AND AIM: Continuous energy restriction (CER) effectively promotes body fat reduction; however, its effects on hunger regulation and the hedonic system (reward-related mechanisms) may compromise long-term weight maintenance. The gut microbiota has emerged as a potential target to support sustained weight loss; however, studies evaluating combined interventions, such as probiotics alongside CER, remain limited. This study aimed to evaluate whether probiotic supplementation enhanced the metabolic and behavioral effects of CER by examining appetite-related hormones (ghrelin, leptin, GLP-1, GIP, and PYY) and eating behavior parameters (emotional eating, cognitive restraint, and binge eating) in adult men with obesity.

METHODS: This was a 12-week randomized, double-blind, placebo-controlled, parallel-group clinical trial. We included adult males living with obesity, aged 25-44 years. The prescribed CER corresponded to a 30% reduction in total daily energy expenditure. Probiotic supplementation consisted of two 1 g sachets per day, each containing 1 × 109 colony-forming units (CFU) of each strain per sachet of Lactobacillus acidophilus NCFM (ATCC SD 5221), Lacticaseibacillus rhamnosus HN001 (ATCC SD 5675), Lacticaseibacillus paracasei Lpc-37 (ATCC SD 5275), and Bifidobacterium lactis HN019 (ATCC SD 5674). Primary outcomes included ghrelin and leptin levels. Secondary outcomes comprised glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), insulin, peptide YY (PYY), and adiponectin levels, as well as eating behavior dimensions and body composition. Binge eating, emotional eating, and cognitive restraint were assessed using the Three-Factor Eating Questionnaire.

RESULTS: Of the 49 participants randomized, 38 were included in the final analysis, with hormonal outcomes available for 25 participants. Significant time effects were observed, indicating that changes were primarily driven by CER, regardless of supplementation group. Ghrelin levels increased over time in both groups (p = 0.045; η2p = 0.164), whereas leptin levels decreased significantly (p < 0.001; η2p = 0.463). Eating behavior improved over time, with reductions in binge eating (p < 0.001; η2p = 0.413) and emotional eating (p = 0.007; η2p = 0.289), and an increase in cognitive restraint (p < 0.001; η2p = 0.650). Absolute fat mass also declined significantly (p < 0.001; η2p = 0.718), with no significant group × time interactions across outcomes. These null findings should be interpreted with caution, as the study was underpowered for ghrelin and emotional eating, potentially limiting the detection of intervention effects.

CONCLUSION: Twelve weeks of CER reduced fat mass and leptin levels and increased ghrelin concentrations, regardless of probiotic supplementation. Eating behavior scores also changed over time, with reductions in binge eating and emotional eating and an increase in cognitive restraint. However, no significant group × time interaction effects were observed, indicating that probiotic supplementation did not provide measurable additional benefits beyond CER for the outcomes assessed.