New research presented at the European Congress on Obesity (ECO 2025) and published in the journal Nutrients suggests that collagen-enriched protein bars could be a safe, affordable, and effective way to lose weight and improve health.
The study found that people who consumed these collagen-infused bars lost twice as much weight as those who did not use the supplement. Additionally, they showed improvements in blood pressure, waist size, and liver health, and may have even gained muscle mass.
Collagen is a protein naturally found in the body’s connective tissues, including skin, muscles, and bones. It is widely known for its role in skin health, but researchers at the University of Navarra in Pamplona, Spain, wanted to understand if it could also help with weight loss.
According to Dr. Paola Mogna-Peláez, the lead researcher, collagen is inexpensive, easy to access, and does not have known side effects, making it an appealing option for weight management.
The team was especially interested in collagen because it can be treated to absorb water, allowing it to expand when consumed. This swelling effect, they hypothesized, could make people feel fuller and reduce their appetite, leading to weight loss.
To test this idea, Dr. Mogna-Peláez and her team conducted a 12-week randomized controlled trial with 64 participants between the ages of 20 and 65, all of whom were overweight or obese. Half of the group was asked to consume a chocolate-flavored protein bar containing 10 grams of collagen before lunch and dinner each day, along with a glass of water.
These collagen bars were specially designed to swell when they absorbed water, expanding in the stomach to create a sense of fullness. Both groups were also given healthy eating advice based on the Mediterranean diet.
The participants filled out appetite questionnaires and underwent regular health checks, including measurements of their weight, blood pressure, waist circumference, and body composition, at the beginning of the study and periodically over the 12 weeks.
The results were promising: the group that consumed the collagen bars lost an average of 3 kg (6.6 lbs) compared to just 1.5 kg (3.3 lbs) for the control group, even though both groups consumed the same number of calories. Researchers noted other health improvements as well:
Blood pressure: The collagen group saw an 8 mm Hg drop in systolic blood pressure, while the control group had a slight increase of 0.4 mm Hg.
Waist circumference: The collagen group lost an average of 2.8 cm, slightly more than the 2.5 cm reduction in the control group.
BMI reduction: Those in the collagen group saw their BMI decrease by 1.2 units, compared to 0.78 units for the control group.
Liver health: The collagen group showed greater improvement in their fatty liver index, which measures liver health.
Importantly, the collagen group also showed an increase in fat-free mass, which includes muscle tissue. This suggests that their weight loss was not just from fat reduction but may have also included muscle building.
The researchers used the sarcopenic index—a measure of muscle mass—to confirm that muscle was not lost during the weight loss process. In fact, the collagen group seemed to build muscle, which is significant because muscle burns more calories than fat, potentially supporting further weight loss.
The appetite questionnaires backed up the physical findings. People in the collagen group reported feeling less hungry and more satisfied after eating, which likely contributed to their reduced calorie intake. Additionally, levels of leptin, the hormone that signals fullness, were higher in the collagen group than in the control group by the end of the study.
In animal tests, collagen was also shown to lower levels of ghrelin, a hormone that stimulates appetite. Remarkably, when exposed to stomach acid, the collagen supplement swelled to nearly 20 times its original size, which may explain the enhanced feeling of fullness.
Participants also rated the taste of the collagen bars highly, giving them an average score of 8.8 out of 10, which the researchers believe is due to the bars being coated in sweetened dark chocolate. No side effects were reported, further supporting the safety of collagen as a weight-loss aid.
Dr. Mogna-Peláez explained that the study’s findings suggest collagen works by expanding in the stomach, which helps curb hunger and reduces overall food intake.
She also proposed that collagen might help build muscle, which increases calorie burning. There is even speculation that collagen could positively influence gut bacteria, potentially aiding in appetite control and weight management.
These collagen-enriched bars are already available on the market, and the research team is now conducting a larger trial to explore exactly how collagen affects weight loss, particularly in terms of gut health.
If these findings are confirmed in larger studies, collagen could become a widely recommended supplement for weight loss, offering an affordable and safe option for those looking to shed pounds and improve their overall health.
If you care about weight loss, please read studies that hop extract could reduce belly fat in overweight people, and early time-restricted eating could help lose weight.
For more health information, please see recent studies that Mediterranean diet can reduce belly fat much better, and Keto diet could help control body weight and blood sugar in diabetes.
The research findings can be found in Nutrients.
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