The complexity of malnutrition in people living with excess body weight

PURPOSE OF REVIEW: Malnutrition in people living with excess body weight is increasingly recognized but remains frequently overlooked because nutritional screening and assessment commonly rely on body mass index (BMI). This review highlights emerging evidence on protein-energy malnutrition, skeletal muscle mass loss, and micronutrient deficiencies in individuals with excess adiposity, and examines the influence of contemporary obesity treatments on these nutritional disturbances. RECENT FINDINGS: Reduced skeletal muscle mass and micronutrient deficiencies are increasingly recognized in individuals with overweight and obesity. Pharmacological therapies, particularly glucagon-like peptide-1 receptor agonists, and bariatric surgery, produce substantial weight loss accompanied by reductions in skeletal muscle mass. However, these changes may partly reflect physiological adaptations to energy restriction and improvements in muscle composition rather than pathological muscle depletion. Micronutrient deficiencies may occur because of both obesity and its treatment. SUMMARY: Malnutrition in individuals with overweight and obesity represents a complex clinical challenge that cannot be identified using BMI alone. Incorporating nutritional and body composition assessment into obesity treatment is essential to distinguish adaptive tissue changes from clinically significant nutritional compromise and to ensure weight-loss therapies optimize metabolic health while preserving nutritional and functional status.