Twelve of 15 women fighters lost weight on a citrus-peel compound without dieting. The average drop was 0.7 kg, and the researchers made the powder

In sports with weight classes, the contest starts on the scales. Most fighters train heavier than the class they compete in and strip the difference off beforehand, slowly by eating less or quickly by sweating out water in saunas and plastic suits. Both routes cost something: strength, stamina, mood, sometimes health. So a supplement that shifts a little fat while an athlete keeps eating normally would be welcome. Researchers at Shanghai University of Sport think tangeretin might be one. It is a flavonoid found in citrus fruit, most of it in the peel, and the team has been testing it in athletes for several years.

Their latest trial, published online in the Journal of the International Society of Sports Nutrition on 7 October 2026, enrolled 30 women from Shanghai's professional teams: 11 taekwondo athletes, 9 from sanda (Chinese kickboxing), 4 wrestlers, 3 boxers and 3 judokas, average age about 19. They were paired by sport and level, and one of each pair was randomly given the supplement. For 30 days in November and December 2023, every athlete drank a 30 g whey protein shake at breakfast under the researchers' eyes. For half of them, 400 mg of the powder was tangeretin. Nobody was asked to eat less or train differently. Meals came from the training centre's kitchen, the base was closed, and dormitories were checked for outside food.

After a month the tangeretin group weighed 0.72 kg less on average (61.58 kg down to 60.86 kg), while the placebo group was 0.30 kg heavier. Twelve of the 15 on tangeretin lost some weight and five were at or under their competition class; in the placebo group six lost weight and two made their class. Body scans put the change down to fat: about 540 g less in the tangeretin group and about 770 g more in the placebo group, with lean mass up about 600 g on tangeretin and flat on placebo. Body fat went from 23.9% to 22.9%. HDL, the 'good' cholesterol, rose about 9%. The fitness story is thinner than the paper's summary suggests. Treadmill time to exhaustion improved in the tangeretin group and a few leg-strength readings rose, but on aerobic capacity the two groups could not be told apart statistically, and the same was true for triglycerides, cortisol and testosterone. No one reported side effects.

Now the caveats, and there are several. A 0.7 kg loss is about 1% of body weight; the paper itself notes that many fighters cut 5 to 15%. This was a rehearsal, with no real weigh-in or bout at the end, so nobody knows whether it helps on the day. Fifteen athletes per group is very few, and the tangeretin group started out with more lean mass and stronger legs. The supplement is the research team's own product, which they describe as self-developed, and the paper says everyone except the authors was unaware of who got what, which is not the same as a trial where the investigators are blind too. No trial registration number is given. The funding came from a laboratory at the same university, and the authors declare no conflict of interest. None of that makes the result wrong. It makes it a first, small signal from the people with the most reason to hope for one, and it needs repeating by someone else, with a real weigh-in at the end.