Rct

Apple cider vinegar has one well-replicated effect relevant to weight management: modest post-meal blood glucose blunting via acetic acid. A single Japanese RCT found 0.75–1.2 kg more weight loss over 12 weeks with daily ACV. Evidence is real but modest. Safety considerations (tooth enamel, oesophageal irritation) are clinically important.

Three categories of food have RCT evidence for increasing metabolic rate: high-protein foods (via thermic effect and lean mass preservation), caffeine-containing foods (via sympathomimetic stimulation), and capsaicin-rich chillies (via TRPV1 activation). Effect sizes are quantified. Other commonly promoted 'metabolism-boosting' foods have weak or no trial evidence.