A Whey Forward

More than 2 in 3 women in the United States are overweight or have obesity. Extra weight can lead to heart disease, diabetes, cancer, and even premature death. Improved diets, instead of expensive drugs with harmful side effects, are needed to help women lower their energy intake to lose weight. Evidence suggests that diets low in carbohydrates and high in protein, especially whey protein (derived from milk), provide the best dietary option for weight loss. Whey is the watery part of milk that remains after making cheese. It can be made into supplements that help the body retain muscle mass while losing body fat. We call this process of losing body fat while keeping body muscle an anti-obesity effect. 

Whey protein contains a mixture of proteins. One protein, called glycomacropeptide (GMP) makes up 20% of the protein in whey. It is believed that GMP may be a key component contributing to its anti-obesity effects. 

We wanted to understand how GMP could have anti-obesity effects. Our previous studies in mice suggest that GMP helps burn body fat, maintain body muscle mass, and improve the composition of bacteria in the gut. Interestingly, the female mice showed larger benefits when fed GMP compared to the male mice. 

To assess the female-specific benefits of GMP, we chose to first study postmenopausal women, a group with the highest incidence of obesity in the U.S. We conducted a study in 13 women who are obese, postmenopausal, and lack any chronic medical conditions. Women were, on average, 57 years of age, 176 pounds, and had mild obesity. 

The goal of our study was to determine an acceptable dose of a GMP supplement and if what we saw in mice also occurred in humans. The GMP supplement consisted of a powder flavored as vanilla or chocolate mixed with cold water and provided 130 calories and 25 grams of protein per serving. 

The study lasted 3 weeks.

We then compared how their bodies responded at the end of each week of consuming the GMP supplement. This allowed each woman to compare how her individual body changed over those two different weeks.  

To evaluate body changes, we measured four outcomes important for weight loss:

We found that our participants preferred taking a GMP supplement two times a day instead of three. Women ate less food on the days they drank the GMP supplement, likely due to increased daily protein consumption. Subjects felt they could eat less food up to 2 hours after eating a GMP supplement, compared to when they ate the same amount of protein from the soy supplement. This shows that drinking the GMP supplement improves fullness, potentially leading to less eating overall.

Our study on how consuming GMP affects blood sugar and fullness led us to look at another hormone called amylin. Amylin is a fullness hormone that is released into the blood and helps to keep the food in the stomach longer. Amylin also helps to lower the amount of sugar in the blood by stopping its production. 

In our study, the women showed higher levels of amylin after eating a GMP supplement compared with a soy supplement. This indicates that drinking a GMP supplement improves fullness and blood sugar control, which may help women lose weight and reduce the risk of developing diabetes. GMP appears to work in a manner like current weight loss drugs, allowing for a safer and cheaper alternative to losing weight for longer periods of time. 

On top of all this, we also wanted to look at the types of bacteria in the gut. Current research suggests that gut bacteria affect the risk of developing obesity and certain diseases. In addition to this, GMP also impacts the gut bacteria. 

The bacteria found in the gut were different after 7 days of drinking two GMP supplements per day (50 grams of protein total). This tells us that eating extra GMP protein each day can have benefits. This is the first evidence in humans that changes in the gut bacteria occur after eating 50 grams of GMP each day for 7 days. This confirms our previous studies in mice and establishes an acceptable dose of GMP for women. 

Therefore, GMP is unique among protein-rich foods because it can alter the gut bacteria and shows positive effects not seen with weight loss drugs. Benefits accompanying changes in gut bacteria include lower inflammation, weight loss, and better bone health. 

Our study shows that a GMP supplement consumed twice a day for 7 days has the potential to improve fullness and blood sugar levels and promote weight loss in postmenopausal women with obesity. This increase in protein intake helps induce weight loss from body fat while preserving muscle. 

In the future, researchers need to look at how GMP impacts male weight loss and obesity. We would also like to incorporate other weight loss tactics, such as exercise, to see how GMP and exercise work together to decrease obesity. Our findings confirm that GMP is a key component in whey protein, contributing to its anti-obesity effects. An active lifestyle with GMP provides a “whey” forward to treat obesity and avoid the expense and risks of weight loss drugs.


Written By: Denise Ney

Academic Editor: Neuroscientist

Non-Academic Editor: Local High School Student

Original Paper

• Title: Glycomacropeptide impacts amylin-mediated satiety, postprandial markers of glucose homeostasis and the fecal microbiome in obese postmenopausal women.

• Journal: The Journal of Nutrition

• Date Published: 26 April 2023

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