Key TakeawaysScientists now recognize four obesity phenotypes. Phenotypes describe how the body reacts to food on a hormonal level.A new test can determine whether you are positive or negative for one of those phenotypes, referred to as “hungry gut.”Testing costs are out-of-pocket at the moment but may allow clinicians to prescribe less expensive medications that work for specific phenotypes.

Key Takeaways

Scientists now recognize four obesity phenotypes. Phenotypes describe how the body reacts to food on a hormonal level.A new test can determine whether you are positive or negative for one of those phenotypes, referred to as “hungry gut.”Testing costs are out-of-pocket at the moment but may allow clinicians to prescribe less expensive medications that work for specific phenotypes.

The frenzy for GLP-1 drugs like Ozempic and Wegovy has created a multi-billion dollar market, with more people trying the expensive medications that the supply can support. But not everyone responds well to these injectables, which can make the financial investment even more painful.

What Is a Phenotype?

The test, which uses a cheek swab to collect genetic material, was tested on 84 participants with obesity who were taking semaglutide, the active ingredient in medications like Wegovy, Ozempic, and Rybelsus. The test results were analyzed using a machine learning gene risk score (ML-GRS) to reveal whether a person was positive or negative for one of the obesity phenotypes: hungry gut.

Participants who were positive lost 19.5% of their total body weight, while those who were negative lost only 10%. While both are significant, people who were “hungry gut positive” were much more likely to have success on semaglutide.

“Our gut makes this hormone called GLP-1—it goes to the brain from our stomach and makes us feel full,” Acosta told Verywell. “But these patients eat a normal meal, and then want to eat again within an hour or two.”

GLP-1 medications work because they simulate the naturally-produced hormones for a continuous feeling of fullness. But for patients who do feel satiated in between meals, they may not have as impressive results, leading to dissatisfaction.

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The Cost of Progress

Although GLP-1s have shown remarkable results, they are also very expensive and in short supply. Acosta said that the test, which is currently commercially available, will be a valuable tool for physicians as they prescribe medications to their patients. The test costs $500 out-of-pocket.

“We know from previous studies that if you don’t have that phenotype, you may not respond as well,” Acosta said. “If you have another phenotype, particularly hungry brain, there are other medications that are cost-effective at only $100 a month. What we are proposing is that not everyone needs to [be] taking expensive Ozempic or [other brands of] semaglutide.”

Cost is an ongoing issue, agrees Rekha Kumar, MD, associate professor of clinical medicine and attending endocrinologist at Weill Cornell Medicine and lead of medical affairs at Found.

“The tricky part is that an insurance company isn’t going to cover a non-FDA approved test that costs $500 to see if $1,000 medicine is going to work,” Kumar said. “Each generation of GLP-1 we see coming out seems to be effective for a larger percentage of the population.”

While the test may seem cost-prohibitive at the moment, Kumar said that there is likely a great audience for it—namely, physicians who don’t have the training that obesity management physicians use to customize treatments for their patients. She said that many endocrinologists use a combination of biomarkers, medical history, family history, and response to prior weight loss attempts to determine the best options for a patient’s medications.

“With a really good medical history, we can get pretty close if we’re sophisticated doctors,” Kumar said. “But as the number of clinicians grows that want to prescribe these drugs, but they don’t have the training, Dr. Acosta’s test could be more useful.”

Who Can Prescribe Anti-Obesity Medications? Why the Type of Provider You See Matters

What This Means For YouAs the business of weight loss continues to grow, testing methods may become much more important. If you’re interested in trying a GLP-1, talk to a doctor who has experience in weight loss management or ask about phenotype testing to determine the right pharmaceutical course for you.

What This Means For You

As the business of weight loss continues to grow, testing methods may become much more important. If you’re interested in trying a GLP-1, talk to a doctor who has experience in weight loss management or ask about phenotype testing to determine the right pharmaceutical course for you.

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