High-Protein Diet Intervention Based on Whey Protein Supplementation Improves Weight Cycling by Reducing Metaflammation

<strong>Background</strong> Weight cycling, characterized by repeated weight regain after weight loss in individuals with obesity, exacerbates long-term metabolic burden and increases the risk of chronic diseases. Exploring intervention strategies based on food components is therefore of great significance. <strong>Objective</strong> This study investigates the effects of a high-protein diet (HPD) supplemented with whey protein on weight change and metaflammation, exploring its underlying molecular mechanisms. <strong>Methods</strong> Ninety-four subjects with obesity and weight cycling were recruited for a three-month HPD intervention supplemented with whey protein. Body composition, basal metabolism, and biochemical parameters were assessed pre- and post-intervention. A weight-cycling mouse model was used to compare the effects of HPD and calorie-restricted diet (CRD) interventions on metaflammation and weight cycling. Bioinformatics and machine learning were utilized to analyze adipose tissue metaflammation and immune microenvironment changes focusing on the regulation of biochemical pathways. <strong>Results</strong> The HPD led to significant reductions in body weight, body fat percentage, waist-to-hip ratio, and visceral fat index, alongside improvements in muscle mass, blood glucose, lipid levels, and blood pressure (<em>P &lt; </em>0.05). The HPD significantly reduced systemic and adipose tissue metaflammation via the TLR4-NLRP3 pathway. Protein levels of NLRP3 and TLR4 in white adipose tissue were lower in the HPD and CRD groups compared to the weight cycling group (<em>P &lt; </em>0.05). Machine learning identified key genes predicting weight regain—IFNGR1 and SCRN2. Single-cell analysis revealed enriched macrophages and IFNGR1-high NK cells, suggesting their roles in metaflammation inhibition. <strong>Conclusion</strong> Supplementation of a high-protein diet with whey protein effectively reduces metaflammation, decreases body weight and fat, and improves metabolic health in individuals with obesity and weight cycling. These benefits are associated with downregulation of the TLR4-NLRP3 pathway and activation of the Wnt pathway. Metaflammation driven by M1 macrophages and NK cells is linked to weight cycling, with IFNGR1 and SCRN2 serving as potential markers for long-term weight control.