Spanish researchers find cheap supplements can double the weight loss results
Can the common proteins found in your connective tissue become the next affordable weight management solution? New research suggests collagen supplements may provide significant benefits for those seeking weight loss without expensive medications.
A 12-week clinical trial published at the European Congress of Obesity (ECO 2025) and a clinical trial published in the Journal of Nutrition that showed that participants who consumed collagen-rich protein bars weigh twice as much as those who did not receive supplements while experiencing many other health improvements.
These findings are an alternative to expensive weight loss medications that have recently made headlines in many people seeking cost-effective alternatives to costly weight loss medications. Unlike these drugs, collagen seems to work through a novel mechanism, resulting in a natural sense of fullness.
How collagen creates a full feeling
“Many weight loss pills are very expensive,” explains Dr. Paola Mogna-Peláez, a researcher at the University of Navarra, Pampurona, Spain. “We are interested in collagen because it is a cheap and easy to access and is not aware of any side effects. It is also a compound that is familiar to the public.”
The secret to collagen’s effectiveness may lie in its unique structure. “It is crucial that the structure of collagen can be modified to allow it to absorb excess water, resulting in an increase in its size,” Dr. Mogna-Peláez noted.
This property allows collagen to expand in the stomach after consumption, creating a feeling of fullness, thereby reducing overall appetite and food intake.
Impressive results beyond weight loss
The randomized controlled trial involved 64 people aged 20-65 who were overweight or obese. All participants received healthy dietary advice based on the Mediterranean diet, but half of the chocolate-flavored protein bars rich in collagen (10 grams per rod) were also required before lunch and dinner.
After 12 weeks, the results showed that the collagen group had several significant improvements compared with the control group:
*Big weight loss (3kg/6.6 lbs vs 1.5kg/3.3 lbs)
*Reduced systolic pressure (8 mm Hg decreases with an increase of 0.4 mm Hg)
* Greater reduction in waist circumference (2.8 cm to 2.5 cm)
* Greater reduction in BMI (1.2 units vs. 0.78 units)
* Improved liver health measurements
*Increasing fat-free mass, indicating potential muscle growth
Interestingly, these improvements occur despite the fact that both groups consumed similar calorie amounts, suggesting that the mechanism of collagen extends beyond simple calorie limits.
How does it work?
The research team proposed several possible mechanisms for collagen weight loss effects.
“Our results show that collagen makes participants feel hungry, which causes them to eat less, so losing weight will lose weight,” explains Dr. Mogna-Peláez.
The results of the questionnaire confirm this theory, suggesting that the collagen group reported hunger and fuller throughout the study period. Laboratory analysis also showed that in the collagen group, leptin levels were higher, a hormone that induces satiety.
In complementary animal experiments, researchers found that collagen lowers levels of hormones that stimulate appetite. Perhaps most impressive is that the supplement expands almost 20 times its original size in stomach acid and exhibits low digestibility-physical properties that may lead to its fullness effect.
Benefits besides weight management
In addition to weight loss, these findings are particularly promising in the potential muscle performance and even muscle building effects of supplementing collagen.
“Collagen can also cause participants to build muscle, and we know that muscle burns more calories than fat,” Dr. Mogna-Peláez noted.
This may create a benign cycle that allows for increased muscle mass to lead to higher metabolic rates, potentially supporting initial intervention expectations outside long-term weight management.
The researchers also believe that collagen may affect gut bacterial composition, which may further aid weight loss and appetite control – although this remains an area for future research.
Tasty, practical and side effects
Unlike many dietary interventions suffered due to taste or convenience issues, the collagen bars in this study earned a delicious high score. Participants rate the chocolate-coated bar as an impressive 8.8 out of 10 servings.
Perhaps most importantly, none of the participants reported any side effects throughout the 12-week trial, supporting collagen’s reputation as a well-tolerated supplement.
The collagen-rich protein bars used in this study are already commercially available. The team is now conducting larger trials to explore the mechanism in more detail, focusing especially on the potential impact on the gut microbiota.
For those struggling with weight management, they find prescription drugs financially out of reach, and these findings suggest that collagen supplementation may provide accessible, effective alternatives worth considering.
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