"Boost your metabolism" is overused as a marketing phrase. The actual biological reality: resting metabolic rate (RMR) is mostly a function of body composition, age, and genetics. But there are a handful of interventions with real evidence — the six below each produce measurable shifts in energy expenditure.

1. Build and keep muscle

Each kilogram of muscle burns roughly 13 kcal/day at rest versus 4 kcal/day for fat mass. Ten kg more muscle over a decade of training = ~100 extra kcal/day, indefinitely. The single highest-leverage metabolic intervention available.

2. Eat protein at every meal

Thermic effect: 20-30 % of protein calories are burned digesting it, versus 5-10 % for carbs and 0-3 % for fats. A 100 g protein day translates to ~100-150 "free" kcal burned relative to an equivalent-calorie low-protein day.

3. Interval training (2x/week)

EPOC (after-burn) keeps oxygen consumption elevated for hours post-workout. Intervals produce noticeably more EPOC than equivalent steady-state cardio.

4. Drink cold water

Small but real thermogenic effect from warming ingested water. Five 250 ml glasses of cold water/day adds maybe 20-40 kcal burn — trivial individually, but the practice also supports general hydration which affects a bunch of other metabolic markers.

5. Sleep 7-8 hours

Undersleep suppresses thyroid hormone and raises cortisol — both of which slow metabolism and drive fat storage. The single most commonly-ignored metabolic intervention.

6. Caffeine and green tea (modest effect)

EGCG + caffeine combined lift metabolic rate 3-5 % for several hours. Not dramatic, but compounds with the other interventions.

What doesn't work

"Metabolism-boosting" spices, apple-cider-vinegar shots as metabolism fixes, breakfast being non-negotiable, six small meals — these are variations on wellness folklore with weak or null evidence. Save the attention for the six above.