MuscleTech Hydroxycut Hardcore Elite

Caffeine· evidence: Strong

Caffeine is one of the best-supported performance aids, with consistent research showing it can improve endurance, strength and alertness. The doses used in research are usually 3–6 mg per kg of body weight, taken about an hour before exercise.

The catch is the dose: it adds to any coffee, tea or energy drinks you already have, and it can disrupt sleep if taken later in the day. There is no authorised health claim for caffeine and sports performance in the UK.

Typical dose: Research doses are 3–6 mg per kg of body weight

Safety: High caffeine content. Not recommended for children or pregnant or breastfeeding women. Healthy adults should keep total caffeine from all sources to no more than 400 mg a day and 200 mg at a time. Avoid late in the day and do not combine with other caffeine products.

Research we looked at:
Guest NS et al. (2021). International Society of Sports Nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr 18:1.
EFSA NDA Panel (2015). Scientific opinion on the safety of caffeine. EFSA Journal 13(5):4102.

Yohimbe / yohimbine· evidence: Insufficient

Yohimbine comes from the bark of the African yohimbe tree. It is a stimulant that acts on the nervous system, and it is sold in some fat burners on the idea that it helps release stored fat. There is very little good human evidence for fat loss: one small study in athletes is often quoted.

EFSA was unable to set a safe intake for yohimbe bark in food, and yohimbine is a prescription-only medicine in the UK. We make no claims about its effects and would not recommend it.

Typical dose: No safe dose has been established for food supplements

Safety: Can cause a fast heart rate, raised blood pressure, anxiety, panic, sweating, headaches and sleeplessness, and the effects are worse alongside caffeine. Do not use if you have a heart condition, high blood pressure, anxiety or other mental health conditions, kidney or liver problems, or take antidepressants or blood pressure medicine. Not for under-18s, pregnancy or breastfeeding.

Research we looked at:
EFSA ANS Panel (2013). Scientific opinion on the evaluation of the safety in use of Yohimbe (Pausinystalia yohimbe (K. Schum.) Pierre ex Beille). EFSA Journal 11(7):3302.
Ostojic SM (2006). Yohimbine: the effects on body composition and exercise performance in soccer players. Res Sports Med 14(4):289–299.

Green coffee bean extract· evidence: Insufficient

Green coffee extract is made from unroasted coffee beans and is high in chlorogenic acids, plus some caffeine. It was heavily promoted for weight loss on the basis of a few small trials. A systematic review found the trials were few, small and of poor quality, and one of the best-known trials was later retracted.

Green coffee is a botanical, and botanical health claims are not authorised in the UK, so we make no claims about what it does.

Typical dose: Products usually give 200–400 mg extract a day

Safety: Contains caffeine; count it in your daily total. Can cause headaches, stomach upset and sleeplessness. Not for under-18s, pregnancy or breastfeeding.

Research we looked at:
Onakpoya I, Terry R, Ernst E (2011). The use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trials. Gastroenterol Res Pract 2011:382852.

Cost per daily dose lets you compare packs of different sizes fairly.Worked out from our current prices.