DY Nutrition Blackbombs Thermogenic Fat Burner

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.

Berberine· evidence: Limited

Berberine is a plant compound from barberry and related plants. It has been studied mainly in people with metabolic conditions, and some reviews report small changes in body weight. Many of the trials are small, short and of mixed quality, and there is little good evidence in healthy people trying to lose fat.

Berberine is a botanical, and botanical health claims are not authorised in the UK, so we make no claims about what it does. Social media has called it 'nature's Ozempic'; that comparison is not supported by the evidence.

Typical dose: Studies have typically used 0.5–1.5 g a day in divided doses

Safety: Commonly causes stomach upset, constipation or diarrhoea. Berberine interacts with many medicines, including diabetes medicines (it can add to their effect on blood sugar), ciclosporin, some blood thinners and other drugs processed by the liver; speak to your GP or pharmacist first if you take any medication. Do not use in pregnancy or breastfeeding, or give to babies or children.

Research we looked at:
Ilyas Z et al. (2020). The effect of berberine on weight loss in order to prevent obesity: a systematic review. Biomed Pharmacother 127:110137.
National Center for Complementary and Integrative Health (NCCIH). Goldenseal and berberine: safety and interactions (nccih.nih.gov).

Capsicum (chilli) extract· evidence: Limited

Capsicum extracts contain capsaicin, the compound that makes chillies hot. Studies have looked at small, short-term rises in energy use and changes in appetite after a dose. The effects measured are small, and there is little evidence that they add up to meaningful weight loss over time.

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

Typical dose: Supplements vary widely; studies used a few milligrams of capsaicinoids a day

Safety: Can cause heartburn, stomach discomfort and a burning sensation. Avoid if you have stomach ulcers or reflux. Speak to your GP first if you take blood thinners or blood pressure medicine.

Research we looked at:
Whiting S, Derbyshire E, Tiwari BK (2012). Capsaicinoids and capsinoids. A potential role for weight management? A systematic review of the evidence. Appetite 59(2):341–348.
Ludy MJ, Moore GE, Mattes RD (2012). The effects of capsaicin and capsiate on energy balance: critical review and meta-analyses of studies in humans. Chem Senses 37(2):103–121.

Green tea extract· evidence: Limited

Green tea extract contains catechins (mainly EGCG) and usually some caffeine. Studies have looked at whether it raises the energy the body uses. A Cochrane review found any effect on weight in overweight adults was very small, around a kilogram or less, and not clinically important. Much of the small effect seen may come from the caffeine.

Green tea is a botanical, and botanical health claims are not authorised in the UK, so we make no claims about what it does. It is not a substitute for eating less and moving more.

Typical dose: Products usually give 100–500 mg extract a day; check the label for EGCG and caffeine content

Safety: Concentrated green tea catechins have been linked to rare cases of liver damage. EFSA found that 800 mg or more of EGCG a day from supplements was linked to raised liver enzymes. Take with food, do not exceed the label dose, and stop and see a doctor if you notice dark urine, yellowing skin or eyes, or abdominal pain. Contains caffeine unless decaffeinated; count it in your daily total. Not for pregnancy, breastfeeding or under-18s.

Research we looked at:
Jurgens TM et al. (2012). Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev (12):CD008650.
EFSA ANS Panel (2018). Scientific opinion on the safety of green tea catechins. EFSA Journal 16(4):5239.

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