Plant-Based Diets as a Therapeutic Strategy for Obesity: Modulation of Adipogenesis, Inflammation, Energy Homeostasis, and Metabolic Dysfunction

Background and Objectives: Obesity is a chronic, relapsing disease driven by dysregulated energy balance, appetite, adipose tissue function, and metabolic homeostasis. Dietary modification remains central to long-term management. Plant-based diets (PBDs), particularly those emphasizing minimally processed plant foods, are associated with lower adiposity and improved cardiometabolic health. This review synthesizes human evidence on weight-loss efficacy and mechanisms linking PBDs to obesity and adiposity-related outcomes. Methods: Following PRISMA-ScR guidance, PubMed and Scopus were searched for English-language adult human studies published from January 2010 to August 2026. Of 1439 records identified and 1297 screened after deduplication, 168 studies met the inclusion criteria and were synthesized descriptively. Results: Human studies support beneficial effects of PBDs on spontaneous energy intake, insulin sensitivity, visceral and ectopic lipid accumulation, and circulating lipid profiles. Clinical trials indicate that PBDs can support weight loss, although superiority over other dietary approaches needs further exploration. Proposed mechanisms include lower dietary energy density and greater satiation, improved lipid partitioning, increased postprandial energy expenditure, reduced oxidative and inflammatory stress, and altered gut microbial metabolism and enteroendocrine signaling. Evidence also suggests diet-responsive epigenetic changes. Direct human evidence for effects on central appetite circuitry, brown or beige adipose tissue, and weight-independent molecular pathways remains limited. Conclusions: High-quality PBDs represent a biologically coherent and scalable strategy for obesity management, with evidence suggesting benefits for energy intake and selected aspects of cardiometabolic health, including energy intake, insulin resistance, lipid metabolism, systemic inflammation, and gut-derived signaling. These effects position high-quality PBDs as a promising strategy for reducing the risk of obesity-related complications, including type 2 diabetes, cardiovascular disease, MASLD, and selected cancers. Further well-designed controlled trials will help clarify the independent contributions of dietary composition and the beneficial effects mediated through reduced energy intake and sustained weight loss.