Fat burners: what really works, and what’s just marketing hype

No supplement can make you lose weight. Weight loss is based on a sustained calorie deficit. Here’s what ‘fat burners’ can — and cannot — offer alongside this principle.

The only mechanism that matters

Losing body fat means burning more energy than you consume. Everything else — meal timing, food choices, supplements — simply helps you maintain that deficit more comfortably.

What has a proven effect

Caffeine

This is the best-researched ingredient: it slightly increases energy expenditure and reduces the perception of exertion. The effect remains modest, and tolerance develops after a few weeks of daily use.

Protein

Although often underestimated as an aid to weight loss, protein is actually the most effective tool: it has a strong satiating effect, is highly thermogenic, and, above all, helps preserve muscle mass whilst in a calorie deficit. A whey protein snack keeps you fuller for longer than a sugary snack with the same calorie content.

Fibre

Volume, satiety, regular bowel movements: fibre makes the calorie deficit much more bearable, at no extra cost.

What is overrated

• Exotic ‘fat-burning’ extracts: marginal effects, often measured in vitro or on very small sample sizes.
• Raspberry ketones, garcinia: no convincing evidence in humans.
• Endless ‘thermogenic’ formulas: caffeine is responsible for most of the perceived effect.

The strategy that works

A moderate calorie deficit (300 to 500 kcal), 1.6 to 2.2 g of protein per kilo to protect muscle mass, strength training to give the body a reason to retain that mass, and sleep. The rest is secondary.

Products containing caffeine are not recommended for people with heart conditions, high blood pressure, anxiety or sleep disorders, or for pregnant or breastfeeding women. This information is provided for guidance only and is not a substitute for the advice of a healthcare professional. If you have a medical condition, are undergoing treatment, are pregnant or are breastfeeding, seek advice from your doctor before taking any supplements.