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Supplements for Body Composition: What Changes Fat and Muscle, Not Just the Scale

Supplements for body composition add only a little on top of training and diet, which do most of the work. Creatine taken during resistance training has the best evidence, adding about 1 kg of lean mass (grade A); protein supplements add less (grade A). Most fat-loss pills, such as green tea extract, garcinia and chromium, shift scale weight by about 1 kg or less without a clear drop in fat. Ask a doctor first if you have kidney disease.

Published How we grade evidenceEditorial policy

The short version

Is losing weight the same as improving body composition?

No. Body composition is the split between fat mass and lean mass (muscle, bone, organs and body water). A scale weighs both at once.

Grade A. Training and diet move the split far more than any pill. In people with overweight or obesity, weight training plus a calorie cut lowered body fat percentage by 3.8 points against no program while lean mass held steady (Lopez 2022). During a diet, adding exercise kept 0.87 kg more fat-free mass than dieting alone, and programs that mixed strength and endurance work did best, at 1.20 kg (Deller 2026).

The scale can mislead in both directions. Five days of creatine loading at 20 g a day raised body weight and fat-free mass, with no change in fat, in 15 men and 15 women (Mihic 2000). Part of that early gain is water: in a 42-day trial in female college dancers, creatine raised total body water along with measured lean mass (Brooks 2023). HMB, by contrast, nudged weight up in young lifters without adding any fat-free mass (Jakubowski 2020).

Does creatine change body composition?

Grade A for lean mass, if you train. A 2022 review of 35 randomized trials (1,192 people) found creatine raised lean body mass by 0.68 kg overall, and the gain was clear only when it was paired with resistance training. Men gained 1.46 kg on average; the 0.29 kg gain in women was too small to rule out chance (Delpino 2022).

Grade B for fat, where the effect is small and inconsistent. Two reviews, each pooling 12 trials of adults under 50 doing resistance training, disagree. One reported fat mass 0.73 kg lower and lean mass 1.14 kg higher with creatine than with training alone (Desai 2024). The other, covering 266 people, found body fat percentage 1.19 points lower but a fat-mass difference of only 0.18 kg, which could be chance (Candow 2023). In neither review did creatine add fat.

Does protein powder change body composition?

Grade A for lean mass, with training. Pooling 49 trials of healthy adults on lifting programs of 6 weeks or longer, extra protein raised fat-free mass by 0.30 kg on average and by 0.75 kg in people who already trained. Beyond a daily total near 1.6 g per kilogram of body weight, extra protein brought no further gain (Morton 2018).

Grade B for fat, with no clear change. In 10 pooled trials of women aged 55 and older, whey did not change fat mass or weight whether or not they exercised, and it raised leg lean mass only in those who lifted (Kuo 2022).

Does collagen work like other protein for muscle?

Grade C. Three German trials gave 15 g of collagen peptides a day during 12 weeks of resistance training: to 53 older men with sarcopenia (age-related muscle loss), to 77 premenopausal women and to 57 young men. Each found more fat-free mass than placebo, and the older men lost 5.4 kg of fat against 3.5 kg (Zdzieblik 2015; Jendricke 2019; Kirmse 2019).

Two caveats. All three tested one company's peptides, and that company or a collagen research institute helped pay for each trial. The placebo was silica, with no protein or calories, so the trials show that adding 15 g of protein helped, not that collagen beats whey. In the young men, muscle fibers grew equally in both groups, and the authors suspected the extra lean mass was connective tissue (Kirmse 2019).

Does HMB build muscle or burn fat?

HMB (beta-hydroxy-beta-methylbutyrate) is a compound the body makes from leucine, an amino acid.

Grade B for no added effect on top of training. In trials pooling 596 older adults, adding HMB (usually 3 g a day) to resistance training did not change limb lean mass, fat mass or weight more than training alone did, though grip strength and a physical-performance score rose a little (García-Alonso 2025). In 11 trials of adults aged 18 to 45, HMB did not change fat-free mass or fat (Jakubowski 2020).

Grade B for a small lean gain in older adults who aren't training. Across 21 trials in people over 50, HMB added 0.28 kg of lean mass (Li 2025). An earlier review found the gain when HMB was taken alone, and none when it was added to exercise (Lin 2021). Our database page marks HMB as improving muscle mass; that fits only older adults who don't train.

Does CLA reduce body fat?

CLA (conjugated linoleic acid) is a group of fats found in meat and dairy.

Grade B for fat, with no clear difference in the better trials. Pooling every trial that measured it, a 2024 review found 0.44 kg less fat mass with CLA, but the high-quality trials showed no change in fat mass or body fat percentage. Those trials did find a small rise in fat-free mass and a small fall in weight, and the authors said the weight change may be too small to matter (Asbaghi 2024). Our condition page lists CLA as lowering body fat; the high-quality trials don't support that.

Do green tea extract and caffeine burn fat?

Grade B for green tea extract and fat mass, with no clear difference. A 2023 review of 59 trials with 3,802 people found green tea extract lowered weight and body fat percentage but not fat mass in kilograms (Asbaghi 2023). In a Cochrane review, 6 trials outside Japan (532 people, 12 to 13 weeks) found a weight difference of just 0.04 kg (Jurgens 2012).

Grade C for caffeine. In 13 trials (606 people), caffeine was linked with a fall in weight and fat mass that grew with the dose: each doubling of intake went with a 28% larger drop in fat mass. The trials varied so much that the true size is uncertain (Tabrizi 2019).

Do carnitine, chromium or berberine help?

Grade B for a small weight drop with carnitine, and grade C for fat. Pooled trials found weight came down 1.21 kg with L-carnitine, an effect that leveled off at about 2,000 mg a day. In the higher-quality trials alone, the weight result held up but the fat result did not (Talenezhad 2020).

Grade B for a small weight drop with chromium. In a Cochrane review, 6 trials (392 people) pooled to a 1.1 kg larger weight loss over 12 to 16 weeks, rated low-quality evidence, and found no firm evidence on body fat percentage (Tian 2013). A larger 2019 pooling put body fat percentage 0.68 points lower, and its authors still called chromium's value for weight loss uncertain (Tsang 2019). Grade C for muscle, with no clear difference: in two 12-week trials in adults aged 54 to 71 who lifted weights, 924 mcg of chromium picolinate a day added nothing to the muscle or strength gains from training (Campbell 1999; Campbell 2002). Our condition page marks chromium as improving muscle mass; the trials it lists found no added effect.

Grade B for berberine, for weight only. A 2026 review of 23 trial reports found weight 0.88 kg lower and a smaller waist with berberine. It reported weight and waist measures, not fat or lean mass, and the authors asked future trials to state each product's purity and dose (Elahi Vahed 2026). Our protocol page lists it as a core item; we grade it for weight only.

Does ashwagandha change body composition?

Grade C for body fat, with no dependable change. A 2026 review pooled 3 trials (161 people) that paired an ashwagandha root extract with weight training. Body fat showed no clear effect, and the strength gains lost significance under a stricter test, each one hinging on a single trial (Lee 2026).

What we'd skip

  • Garcinia (hydroxycitric acid). Pooled trials showed 0.88 kg more weight loss than placebo, of uncertain clinical value, and stomach and gut side effects were twice as common in one trial. The review had no fat data (Onakpoya 2011).
  • Glucomannan, a fiber from konjac root. Across 8 trials, weight loss was 0.22 kg more than placebo, which could be chance (Onakpoya 2014). A later network analysis put it at 1.36 kg with low certainty, and it measured weight only (Shahinfar 2023).
  • Products sold on scale-weight results alone. Lost weight can be muscle and water, not just fat.

Safety and interactions

  • Protein and kidneys. A nephrology review warns that high protein intake strains the kidney's filters, and animal protein was tied to kidney failure in several observational studies. If you have kidney disease or are at high risk of it, raise protein only with your doctor (Ko 2020).
  • Creatine and lab tests. Creatine nudges up serum creatinine, the usual kidney blood test. In pooled trials the rise was clearest in the first week and again after 12 weeks, while measured kidney filtration did not change (Naeini 2025).
  • Green tea extract and the liver. Case reports tie liver injury to 140 mg to about 1,000 mg of EGCG (the main green tea catechin) a day, and taking it on an empty stomach raises blood levels. A US standards body asks labels to say: take it with food, and skip it if you have liver problems (Oketch-Rabah 2020). European food-safety experts found that 800 mg of EGCG a day or more from supplements raised liver enzymes in trials (EFSA 2018).
  • CLA and blood sugar. In 60 men with belly obesity, 12 weeks of one purified CLA form raised insulin resistance by 19% and lowered HDL ("good") cholesterol; the usual CLA mix also lowered HDL (Risérus 2002).
  • Berberine and medicines. Two weeks of berberine, 300 mg three times a day, raised blood levels of midazolam, a test drug, by about 40% and slowed two more drug-processing enzymes (Guo 2012). In type 2 diabetes, its effect on blood sugar added to that of glucose-lowering drugs (Liang 2019).
  • Chromium and medicines. Chromium may push blood sugar too low if you use insulin, metformin or other diabetes drugs, and it can cut absorption of levothyroxine (thyroid hormone). Go easy on high amounts if you have kidney or liver disease (NIH ODS).
  • Ashwagandha and the liver. In 5 reported cases of liver injury, itching and raised bilirubin lasted 5 to 20 weeks, though none led to liver failure (Björnsson 2020).
  • Caffeine. For most adults, the FDA cites 400 mg a day as an amount not generally linked with harm, and about 1,200 mg taken quickly can cause seizures. Count coffee, pre-workout drinks and fat burners together (FDA).
  • HMB, collagen peptides and CLA. No interaction studies were found.

When to see a doctor

  • Weight or muscle loss you didn't plan, especially after 65, when it goes with higher rates of illness and death. Doctors check medicines, blood tests and age-appropriate cancer screening (Gaddey 2021).
  • Yellow skin or eyes, dark urine or belly pain after starting green tea extract, ashwagandha or any fat burner. Stop it and get liver tests (Oketch-Rabah 2020).
  • Kidney disease or reduced kidney function, before you raise protein or start creatine.
  • If you take a GLP-1 medicine, insulin or another diabetes medicine, ask the prescriber before adding chromium or berberine. Don't stop a prescribed medicine on your own; ask the prescriber or pharmacist.

If you are pregnant, breastfeeding or under 18, ask a clinician.

FAQ

What is the best supplement for body composition? Creatine taken during a resistance training program has the strongest evidence, adding about 1 kg of lean mass (grade A). Protein supplements come next, and both work only alongside training.

Does creatine make you gain fat? No. Creatine raises scale weight through lean mass and body water, while fat stayed the same or fell slightly in trials.

Does CLA burn belly fat? Not in the high-quality trials, which found no change in fat mass. One purified form of CLA made insulin work less well in men with belly obesity.

Sources

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