The skyrocketing popularity of GLP-1 receptor agonists has transformed the weight-loss industry, but not all shots are created equal in terms of how they work.

A study published in Nature investigated how genes affect the success of modern weight-loss drugs — specifically, GLP-1s like semaglutide and tirzepatide.

In analyzing genetic data and self-reported weight loss from over 27,000 users, researchers pinpointed a specific variation in the GLP-1 receptor gene (GLP1R) that acts as a “booster” for the drug’s effectiveness.

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Individuals carrying one copy of this variant lost an average of 1.6 pounds more than those without it, according to the findings.

This suggests that genetic testing could eventually help doctors steer sensitive patients toward medications they are more likely to tolerate.

“We believe these reports are a step forward in meeting an unmet need for a more informed and personalized approach to weight management,” said study co-author Noura Abul-Husn, chief medical officer at the 23andMe Research Institute in California, in a press release.

While this genetic “boost” is measurable, it remains relatively modest when compared to the total average weight loss of 24 pounds observed across the study population, the researchers noted.

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Beyond genetics, other factors such as age, sex and specific medications remain much stronger predictors of success.

For instance, the study found that women generally saw a higher body mass index (BMI) reduction (12.2%) compared to men (10.0%).

The study may also reveal why certain patients experience stomach issues. Scientists identified a different genetic variant that was linked to increased reports of nausea and vomiting.

The presence of this side effect did not impact the drug’s effectiveness, however. Patients with variants in the GLP1R and GIPR genes lost just as much weight as those without it; they simply felt more sick during the process, the study found.

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“GLP-1 treatment decisions are complex, and having access to clinical expertise to help contextualize your genetic results alongside your full health picture is exactly the kind of guidance this report is designed to support,” said Abul-Husn.

Dr. Peter Balazs, MD, a hormone and weight-loss specialist serving the New York and New Jersey area, was not involved in the study but reiterated the role of the genetic variants in treatment response and side effects.

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“Notably, there appears to be a drug-specific effect: The GIPR variant associated with these side effects is observed with tirzepatide, but not with semaglutide,” he told Fox News Digital.

Balazs said he was surprised by the extremely wide nausea risk range (5%–78%). “Additionally, the drug-specific genetic dissociation was unexpected,” he added.

Study limitations

The data relied on participants reporting their own weight, which could be subject to bias.

“The data is self-reported and not medically verified, which may affect its reliability firstly,” Balazs told Fox News Digital. “It also does not account for key treatment variables, such as titration, discontinuation or dosing schedules.”

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The 23andMe participant pool may not reflect a diverse, real-world population, he added.

“The study also lacks data on important clinical endpoints, such as diabetes progression, and severe adverse effects, such as gastroparesis or pancreatitis,” Balazs pointed out. “Many of its findings also have not been supported by more clinically and statistically robust studies.”

For example, a sub-study comparing these reports to objective iPhone health data suggested that participants might over-report their progress. While users reported an 11.8% loss, electronic data in that subset showed a 5.8% loss.

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As an observational study rather than a controlled clinical trial, it could not definitively prove that the genetic variants caused the difference in weight loss, only that they are associated with it, the researchers noted.

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“I think this article is interesting, raising the possibility of genetic factors, and the use of genetic testing incorporated into further decision-making when picking weight-loss medications,” Balazs said. “However, I would be careful to draw conclusions solely based on this study.”

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Sleeping with, or without, a pillow may have a sneaky impact on your health.

New research suggests that skipping the pillow could help prevent the development of glaucoma, an eye disease that damages the optic nerve and can cause vision loss or blindness.

Glaucoma can be caused by elevated eye pressure, thinning of the optic nerve or fluid buildup, according to the Glaucoma Research Foundation.

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The study, published in the British Journal of Ophthalmology, found that eye pressure was higher in glaucoma patients who slept with two pillows compared to lying flat. Blood flow to the eye decreased in the high-pillow position.

This may occur due to the neck bending forward, compressing the veins, the authors suggested. Glaucoma patients may benefit from avoiding sleep postures that put the neck in this position, they concluded.

Dr. William Lu, medical director at Dreem Health, who was not involved in the study, called these findings “interesting and important.”

“It highlights how something as simple as sleep posture can influence intra-ocular pressure in people with glaucoma,” the San Francisco-based expert told Fox News Digital.

COMMON SLEEP AID COULD BE QUIETLY INTERFERING WITH YOUR REST, STUDY SUGGESTS

“That said, this is still early research, and it doesn’t mean pillows are inherently harmful – it’s more about how they’re used and the degree of elevation.”

The key takeaway is “balance and personalization,” Lu said. Most people don’t need to eliminate pillows, but should avoid “extreme positions,” such as sleeping with the head sharply elevated or with the neck bent at an awkward angle, he noted.

Sleeping without a pillow can help promote a more neutral neck alignment for some people, especially those who sleep on their backs, according to Lu.

“That can reduce strain on the cervical spine and may improve comfort or reduce morning stiffness,” he said. “In certain cases, it may also reduce pressure points that come from overly thick or unsupportive pillows.”

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Going pillow-free isn’t ideal for side sleepers, who often need a pillow to keep the head aligned with the spine, Lu added.

“Without one, the neck can tilt downward and create strain over time,” he said. “For others, skipping a pillow can worsen snoring or airway positioning, and people with existing neck or shoulder issues may actually feel worse without proper support.”

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For those who have glaucoma or are at higher risk, Lu recommends discussing sleep posture with a healthcare provider and aiming for a position that keeps the head and neck aligned without excessive elevation.

“Small adjustments in sleep setup can be a simple but meaningful way to support overall health,” he said.

In a separate interview with Fox News Digital, Dr. Saema Tahir, a board-certified sleep disorder specialist in New York City, said these findings align with prior research showing that “how you elevate your head matters.”

“Elevating the head of the bed itself can reduce eye pressure, but using multiple pillows may not have the same effect – and could even be counterproductive in some cases,” she said.

Tahir stressed that there is “very limited high-quality evidence” showing health benefits from sleeping without a pillow.

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“What matters most is maintaining proper alignment of the cervical spine, and that varies from person to person,” she said. “Without adequate support, especially for side sleepers, the neck can fall out of alignment.”

This can manifest as neck pain and stiffness, morning headaches, or shoulder and arm discomfort.

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“So, for many people, especially side sleepers, skipping a pillow can actually make sleep quality worse,” the expert said.

“For those with glaucoma or at risk should avoid sleeping face-down with pressure on the eyes and should be cautious with very high or stacked pillows … Be mindful of side sleeping, as the lower eye can experience higher pressure.”