Egcg

Green tea's EGCG combined with caffeine produces approximately 80 kcal/day additional expenditure above caffeine alone (Dulloo 1999). Senna-based 'detox teas' produce water/stool weight loss with no fat loss and health risks at chronic use. EFSA has not authorised weight management claims for any tea-based supplement. This article reviews what works and what doesn't.

Natural compounds with RCT evidence for metabolic rate effects: caffeine (100–150 kcal/day, Astrup 1990; tolerance-limited), EGCG from green tea (+80 kcal/day above caffeine, Dulloo 1999), capsaicin (+50 kcal/day, Ludy 2012; tolerance develops). L-carnitine has no evidence for metabolic rate increase in omnivores. B vitamins are essential cofactors but do not boost metabolism above baseline. Total achievable effect: ~200–350 kcal/day in non-tolerant individuals — less than one small meal.

Green tea contains two bioactive compounds — EGCG and caffeine — with documented effects on energy expenditure and fat oxidation. This article examines the mechanism, the quantified effect from clinical trials, and the conditions under which any benefit applies.

Supplement compounds with documented metabolic effects exist — but vary substantially in evidence quality, effect size, dose requirements, tolerance, and safety profile. This review applies systematic criteria to the most widely used metabolism supplement ingredients.

Teas vary substantially in their active compounds, mechanisms, and evidence quality for metabolic effects. This review covers green, oolong, black, white, and yerba mate teas with specific compound concentrations, quantified effects, tolerance caveats, and safety considerations.