What clinical trials exist evaluating oral gelatin or collagen supplements for weight loss?
Executive summary
Hydrolyzed collagen, collagen peptides and gelatin have been widely tested in clinical trials — but almost none of the registered or published randomized trials were designed primarily to test oral collagen or gelatin supplements as standalone weight‑loss drugs; most trials target skin, joint, metabolic or exercise outcomes instead [1] [2]. A small number of randomized controlled trials and subgroup analyses report modest favorable changes in body composition or body‑fat measures when collagen peptides are combined with resistance training or given to overweight adults, but the evidence is limited, heterogenous, and underpowered for definitive weight‑loss claims [3] [4] [5].
1. What trials actually looked at body weight or body‑fat outcomes — and what they found
Randomized trials that measured body composition include studies where specific collagen peptides were administered alongside exercise: for example, a randomized controlled trial reported that specific collagen peptides combined with resistance training improved body composition and regional muscle strength in premenopausal women (summary reported in a systematic review) [3]. A separate randomized, double‑blind, placebo‑controlled trial reported that low‑molecular‑weight collagen peptides derived from skate skin reduced body fat in overweight adults, according to clinical summaries captured in secondary reporting [4]. Systematic reviews and meta‑analyses that collate multiple RCTs typically emphasize skin and musculoskeletal endpoints but note some trials measured fat mass or lean mass as secondary outcomes [5] [3].
2. Trials using gelatin specifically — doses and contexts
Among trials that used gelatin (the denatured form of collagen), doses have varied; two trials cited in a systematic review administered gelatin at 5 g/day and 15 g/day, but these studies were conducted in exercise and recovery contexts rather than weight‑loss programs [3]. Those gelatin trials are therefore more informative about tendon, muscle and exercise recovery endpoints than about calorie‑restricted weight loss, which limits their applicability to claims that gelatin alone causes weight loss [3].
3. Registered but unpublished or ongoing trials: the clinicaltrials.gov picture
ClinicalTrials.gov lists multiple study records for oral collagen products, including entries titled “Oral Supplementation With Active Collagen Peptides and ...” (NCT06321770) and “Gelatin, Collagen, Gummy and PINP” (NCT03357432), indicating ongoing or planned human research into oral collagen/gelatin formulations [6] [7]. Public registry entries show interest across indications, but the registry entries retrieved here do not themselves confirm completed weight‑loss primary endpoints or published results available in the provided reporting [6] [7].
4. How systematic reviews frame the evidence and the limitations they flag
Large systematic reviews and meta‑analyses focus on skin hydration/elasticity and joint outcomes and conclude that hydrolysed collagen has consistent signals for dermal and musculoskeletal benefits, while calling for larger trials and standardized dosing for other indications [5] [1]. Those reviews repeatedly note heterogeneity in product type (gelatin vs. hydrolyzed peptides vs. specific tripeptides), dose, duration and populations studied — problems that weaken cross‑trial conclusions about weight or fat loss specifically [5] [2].
5. Bottom line: evidence for weight loss is limited and suggestive at best
A small set of RCTs reports favorable body‑composition changes when collagen peptides are used with resistance training or in overweight adults, but the trials are not numerous, often small, and many trials have other primary endpoints [3] [4]. Systematic reviews emphasize promising but limited and inconsistent evidence for outcomes beyond skin and joints and call for larger, targeted randomized trials measuring weight loss and metabolic endpoints as primary outcomes [5] [8].
6. What investigative gaps remain and how to interpret marketing claims
Marketing claims that collagen or gelatin supplements cause weight loss outpace the clinical record: registries show multiple trials exist but do not confirm robust, replicated weight‑loss efficacy, and the peer‑reviewed literature is dominated by skin and joint studies with body composition as secondary measures [6] [7] [5]. Proponents point to peptide bioavailability and mechanistic rationale (amino acid profiles, satiety or muscle‑sparing effects), but systematic reviewers insist that a focused, large RCT with weight or fat mass as a primary endpoint is still needed to substantiate weight‑loss claims [1] [5].