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If you’re considering collagen supplements for loose skin after major weight loss, look at what the studies actually measured. Some reviews report improvements in skin hydration or elasticity, but those outcomes measure properties of the skin. In the human research reviewed for this guide, we found no trial that directly tested whether oral collagen reduces excess skin after major weight loss.
Excess skin and age-related changes
After substantial weight loss, skin may hang in folds around areas such as the abdomen, arms, or thighs. A skin-aging study may instead measure how much moisture is in a patch of skin, how well the skin springs back, or how deep a wrinkle is. Those measurements answer different questions from whether the amount of excess skin changed. American Society of Plastic Surgeons overview · 2026 review of oral collagen trials
| Outcome | What it measures | How to read it in a collagen study |
|---|---|---|
| Hydration | Moisture in the skin | A higher reading tells you about moisture at the area tested. |
| Elasticity | How well the skin springs back after stretching | A better reading describes the skin’s response at the test site. |
| Wrinkles | The depth or size of a crease, often on the face | A change describes the crease measured in that study. |
| Excess skin after major weight loss | Overhanging skin, such as an abdominal fold | The relevant trial would measure whether excess skin changed in people after major weight loss. |
What the collagen studies found
A 2025 review of 23 randomized trials found improvements in hydration, elasticity, and wrinkles when it pooled all the trials. When the authors grouped studies by quality and funding, the higher-quality trials and the trials without pharmaceutical-company funding showed no statistically significant improvement in those outcomes. That makes the pooled result less certain than it may sound on a product page. Myung and Park, The American Journal of Medicine
A 2026 review of 35 randomized trials reported improvements in instrument-measured hydration and elasticity. Its analyses found that the apparent improvements in wrinkles and skin density depended heavily on outlier studies and differences between trials. The authors studied skin-aging outcomes. They did not establish that a collagen supplement can reduce an overhanging skin fold after weight loss. Batool and colleagues, Journal of Cosmetic Dermatology
These reviews help explain why supplement claims can sound more certain than the research. A change detected by an instrument at one test site tells you about that measurement. A trial in people with excess skin after weight loss would need to measure the visible or functional changes that matter to them.
What to consider before buying
If your goal is to reduce excess skin after weight loss, the evidence reviewed here gives you little reason to spend money on collagen for that purpose. When a product cites a study, check who took part and what the researchers measured. A claim about firmer-looking skin may refer to an elasticity reading. For a broader look at supplement ingredients and formats, see the collagen supplement guide.
When to talk with a clinician
If skin folds cause recurring rashes or sores, or make hygiene or movement difficult, a clinician can evaluate the symptoms and discuss options. For some people after major weight loss, a consultation may cover whether excess-skin removal is appropriate and what the risks and recovery would involve. MedlinePlus overview of panniculectomy · American Society of Plastic Surgeons overview