Collagen for Weight Loss: What Trials Show

Disclosure: This post contains affiliate links. We may earn a commission if you purchase through our links, at no extra cost to you.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Collagen for weight loss has a thin evidence base: a few small, short trials of 12 weeks or less suggest collagen peptides may help with body fat or a feeling of fullness in specific groups, while others found no difference in appetite, and none shows collagen causing weight loss on its own. I am not a doctor, so this guide sticks to what the published studies tested, who was in them, and where the evidence stops.

If you want the bigger picture first, my guide to the best supplements for women over 40 sorts out which supplements have evidence for what. The NIH Office of Dietary Supplements, in its fact sheet on dietary supplements for weight loss (updated May 18, 2022), notes that in a 2002 report the Government Accountability Office concluded that little is known about whether weight loss supplements are effective, but some supplements have been associated with the potential for physical harm. The fact sheet does not review collagen.

Does collagen help with weight loss?

Collagen is a protein, so it supplies calories and amino acids. The trials below tested it as an add-on to a normal diet, sometimes alongside exercise. Several measured body fat or body composition rather than the number on the scale, and the largest enrolled 77 people. Several of these studies involved collagen makers: authors of the 2024 trial, the 2019 amino acid analysis and the 2025 appetite trial work for collagen companies, and the 2023 trial was supported by Cosmax Co.

What does the research say about collagen and body weight?

Collagen in adults with overweight or obesity

A 2024 randomized trial in Nutrients gave 64 adults (32 men and 32 women, ages 20 to 65) with overweight or obesity healthy-eating advice plus two protein bars enriched with a specially treated bovine collagen (20 g a day), or healthy-eating advice alone, for 12 weeks. Both groups lost weight, but the collagen group lost about 3.0 kg (roughly 6.6 lb) on average and the control group about 1.5 kg (p = 0.045). The collagen group also reported feeling less hungry and more full, but the control group got no placebo bar, so participants knew which group they were in. The authors note the collagen group also ate about 180 extra kcal and more protein. The collagen in that trial was processed to swell in stomach acid, so the result may not carry over to an ordinary collagen powder. It is one 12 week trial.

Collagen with resistance training in women

In a 2019 trial in premenopausal women, 77 women did 12 weeks of resistance training three days a week and took 15 g a day of specific collagen peptides or a placebo. Both groups gained fat-free mass and lost body fat percentage. The collagen group changed significantly more on both measures, which were taken by bioelectrical impedance. Because everyone was lifting, the study cannot say what collagen would do without the training.

Collagen peptides in adults aged 50 and over

A 12 week trial of 74 adults aged 50 and older compared 15 g a day of collagen peptide with a placebo drink. On DEXA, total fat mass was essentially unchanged in the collagen group (down about 0.5 percent, not a significant change from baseline) and rose about 2.2 percent in the placebo group, a significant difference between groups (p = 0.041). Impedance also showed a difference between groups (p = 0.021). Physical activity and diet did not differ between groups. Most participants were women (about 58 of 74, almost all postmenopausal, based on the paper’s Table 1). The researchers measured fat mass, not pounds lost, and a few percent of fat mass is not the same as weight loss.

What a systematic review concluded

A systematic review of 15 randomized trials of collagen peptides plus exercise found the clearest benefit was for joint function and joint pain. It reported “certain improvements” in body composition and strength. Twelve of the 15 studies were in recreational athletes, two in older adults and one in untrained premenopausal women, so women over 40 trying to lose weight are not well represented.

Does collagen help you feel full?

The results are mixed. In a crossover pilot of 10 healthy women (average age 22), a single 40 g dose of hydrolyzed collagen and a single 40 g dose of whey produced no difference in hunger, desire to eat or how much cheese bread they ate two hours later. With no no-protein comparison, the study cannot say whether either one changed appetite.

A crossover trial of 15 active women (average age 23) gave 15 g a day of collagen peptides for seven days. After a 45 minute bike ride, they ate about 10 percent less at the next meal, roughly 41 calories, and had higher GLP-1 (a gut hormone involved in fullness) in their blood. Their own appetite ratings did not differ from the control week. Forty-one calories at one meal in 15 young women does not show a weight loss effect for women in midlife.

Is collagen a complete protein?

No. A 2019 analysis in Nutrients notes that collagen protein lacks one indispensable amino acid, tryptophan, so it is classed as an incomplete protein source. The same paper modeled a typical American diet and found collagen peptides could replace up to 36 percent of daily protein while still meeting indispensable amino acid needs. That was a calculation, not a trial, and the amounts used in the studies it cites, 2.5 to 15 g a day, sit below that ceiling.

That calculation shows how much collagen a typical diet could hold before amino acid needs go unmet. It does not tell you how much protein you need or whether to add collagen, which is a question for your clinician or a registered dietitian. My guide to amino acids for weight loss covers what the essential amino acids do and where the evidence is stronger.

How much collagen did the trials use?

The weight and body fat trials above used 15 g a day of collagen peptides (the 2019 women’s trial and the trial in adults aged 50 and over) or 20 g a day in protein bars. Researchers picked those amounts for their studies. They are not a recommendation, and I cannot tell you what amount is right for you. A supplement label lists grams per serving, and the Supplement Facts panel is where to see the serving size before comparing any product to a study.

What type of collagen is best for weight loss?

No type has been shown best. The weight and body composition trials above did not compare collagen types against each other, and the skin analysis below pooled trials of hydrolyzed collagen, meaning collagen broken into smaller peptides. Labels talk a lot about Type I, II and III, but for weight the research does not back picking one type over another.

Does collagen help skin and joints?

Skin

Skin has more randomized trials behind it than weight does. A 2021 meta-analysis in the International Journal of Dermatology pooled 19 randomized trials with 1,125 participants aged 20 to 70, 95 percent of them women. Hydrolyzed collagen taken for about 90 days beat placebo for skin hydration, elasticity and wrinkles. A 2026 review of 19 trials of oral and topical peptides found improved hydration, a modest wrinkle effect and inconsistent results for elasticity. These trials studied skin aging and did not report on loose skin after weight loss.

Joints

A 2025 meta-analysis of 11 trials with 870 people who had knee osteoarthritis found collagen supplements improved pain and function scores compared with placebo. The trials differed a lot from one another, and the participants had osteoarthritis, which is not the same as general soreness from training. If joint pain is limiting your exercise, that is a conversation for your clinician.

Does vitamin C matter for collagen?

The NIH Office of Dietary Supplements says in its vitamin C fact sheet that vitamin C is required for the biosynthesis of collagen in the body. That describes the body’s own collagen production. The fact sheet does not address whether a collagen supplement needs vitamin C added to it.

Is collagen safe, and who should check first?

The sources used for this page do not include a safety review of collagen supplements. A 2026 meta-analysis of 19 skin-aging trials of oral and topical peptides reported minimal adverse events, but those peptides were not all collagen and the trials were about skin. That does not cover every product, dose or person. The FDA does not approve dietary supplements before they are sold. Makers are responsible for safety and labeling, and the FDA can act after a product reaches the market. A label cannot tell you how a product fits with your health history.

Talk to a clinician first

This is research, not medical advice. Ask a licensed clinician or pharmacist before adding any supplement, including collagen, especially if you take prescription medicine (including a GLP-1 medicine, see my GLP-1 weight loss guide) or you are pregnant or nursing. They can look at your protein intake, your medications and your goals together.

Frequently Asked Questions

Is collagen good for weight loss?

The trials are small and short. Some found lower body fat or lower intake at a meal, one found no difference from whey in hunger, and none shows collagen alone makes you lose weight. Collagen is a protein supplement, not a fat burner.

How much collagen for weight loss?

The body fat trials reviewed here used 15 g a day of collagen peptides or 20 g a day in protein bars, for 12 weeks. That describes what researchers tested. It is not a dose recommendation, so check with your clinician or pharmacist.

Is collagen powder better than protein powder for weight loss?

The research reviewed here does not show that. Collagen lacks tryptophan, so it is an incomplete protein, and the systematic review found collagen had no significant effect on muscle protein synthesis (a muscle outcome, not weight) compared with higher quality protein. Whether protein powder helps you is a separate question.

Will collagen help with loose skin after weight loss?

The skin trials studied aging skin, mostly in women aged 20 to 70, and measured hydration, elasticity and wrinkles. They did not report on loose skin after weight loss, so these sources cannot answer that question.

Does collagen make you feel full?

Maybe, in some people. One trial of 15 active women saw lower intake at the next meal, while a pilot of 10 women saw no difference from whey in hunger or intake. Neither studied women over 40.

Sources

Collagen for Weight Loss: What the Research Shows