Energy-expenditure

The thermic effect of food (TEF) — energy expended in digestion, absorption, and processing — varies substantially between macronutrients and food types. High-protein and high-fibre foods have the highest metabolic costs. This article reviews TEF evidence and practical dietary implications.

Metabolism is the sum of biochemical processes that convert food into ATP. Total daily energy expenditure has four components: BMR (60–70%, calculated with Mifflin-St Jeor), TEF (10%), NEAT (15–30%, 350–750 kcal/day variation — Levine 1999), and exercise. Lean mass is the primary driver of BMR. Metabolic adaptation (Leibel 1995: −250 kcal/day) explains why weight loss slows — and why understanding the physiology is essential for long-term management.

Total daily energy expenditure is influenced by diet composition, protein intake, meal timing, and specific bioactive compounds. This article reviews the mechanistic and clinical evidence on dietary strategies to increase metabolic rate.