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Key points
- The claim is that gelatin taken before eating forms a gel that reduces food intake leading to weight loss.
- The gelling process never occurs in the stomach, and clinical studies show no evidence of weight loss.
As a scientist who studies the impact of nutrition on the brain and general health, I try to stay up to date on popular diets. One of my students pointed me in the direction of claims in Facebook groups and popular wellness communities online that a common diet ingredient, gelatin, can help reduce body weight. It’s called “the overnight gelatin habit.” Proponents claim that it’s a simple daily ritual to calm hunger signals that doesn’t require prescriptions, food tracking, or exercise
That’s an amazing claim, but things that sound too good to be true usually are
We are all familiar with the popular food Jell-O. The name is clever because it is a play on “gelatin,” the peptide that turns flavored water into a jelly. Today pseudoscience influencers are pushing the message that a tablespoon of gelatin, the precursor to Jell-O, if taken a half-hour before eating, will leave no room for other foods in the stomach and therefore lead to weight loss
Gelatin can turn water into a thickened gel. That molecular magic has been known since antiquity when farmers discovered that boiling animal skins, bones or tendons produces a broth that sets into a solid jelly on cooling. We now understand the chemistry of this phenomenon. Collagen is a protein extracted by hot water from animal tissues. When it is sufficiently heated, the large collagen molecules break down into smaller peptides called gelatin. The small gelatin peptides move freely in solution; as the solution cools, they form weak bonds with each other, trapping water molecules in the process—resulting, when combined with flavorings, in a tasty gel. [Pearle Bixby Wait, in 1897, a carpenter who was searching for a cough remedy and laxative tea, is credited, along with his wife, May, of inventing and naming the fruit-flavored dessert Jell-O.]
Does the gelatin claim make sense?
The claim that gelatin forms a gel that fills the stomach is bogus. To produce a gel, gelatin has to be heated and then cooled. This will not happen at 37oC, roughly the temperature of the stomach. As anyone who has ever made Jell-O knows, the water has to be heated to near boiling to dissolve the gelatin. Obviously, that will never happen. So, gelling in the stomach is not a legitimate claim for the supposed appetite-reducing effect of gelatin
How did this rumor go viral?
In the case of gelatin, the concept arose from a study from Holland’s Maastricht University. It’s a well-known fact that some proteins can suppress the appetite. The researchers investigated whether the specific amino acid content is important. They compared the milk protein casein, which contains a good balance of all the amino acids that we need, to gelatin, which does not contain a complete balance of all the essential amino acids. The hypothesis was that the lack of essential amino acids would cause the body to reject an imbalanced diet and result in a suppression of hunger. [For more, click here.]
The study design was flawed. Subjects were simply asked to give a numerical estimate to the question “How hungry do you feel right now?” at various times after consuming a meal that contained at least 50 grams of gelatin or an equal amount of casein. 50 grams is considerably more than the 7-8 grams of gelatin found in 1 tablespoon, which is the amount recommended online for the “gelatin weight-loss trick” to work. The study reported that the 50-gram dose of gelatin did suppress hunger—but failed to determine whether the subjects consumed less food! This study is often referenced by online supporters of this diet; unfortunately, the study never presented evidence of reduced food intake in response to the gelatin. A later study by the same lab (Hochstenbach-Waelen et al., 2010) followed 72 overweight people who over 8 weeks consumed a gelatin-laced meal that, according to the previous study, should have reduced calorie intake at the next meal and therefore lead to weight loss. It didn’t. The study failed to show any weight loss associated with consumption of gelatin.
Gelatin’s supposed trick of causing weight loss is just an illusion
- What are healthy approaches to dieting?
- Take our Healthy Lifestyle Test
- Find a health professional
A. Hochstenbach-Waelen A, et al., (2010) No long-term weight maintenance effects of gelatin in a supra-sustained protein diet. Journal Physiology & Behavior, 101:237-244. doi.org/10.1016/j.physbeh.2010.05.005
