Doesn’t it seem like everyone you know is either taking or thinking about taking a GLP-1 medication these days? The numbers would agree. According to a recent KFF Health Tracking Poll, 12% of adults in the US report having tried one at some point, and 6% of US adults say they are currently taking one. And the number of active users is expected to grow by 50% within 5 years to 9% of the US adult population. According to a recent NY Times article, even doctors and cardiologists have joined in on the quest to be thinner. And more than half of the US population is now eligible for GLP-1 medication.
Glucagon-like peptide-1 (GLP-1) is a naturally occurring hormone produced in the intestines within minutes of ingesting food. It helps regulate blood sugar levels, delay digestion, and reduce appetite.
Glucagon-like peptide 1 receptor agonists (GLP-1RAs) are a class of prescription drugs that mimic the effects of the natural hormone. They have been used since 2005 for type 2 diabetes. With names like Wegovy, Zepbound, and Saxenda, they have also been used for obesity and cardiovascular health since 2014. And it’s that second category that seems to be driving an increase in their use nationwide.
Ongoing research is looking at other ways that GLP-1 medications can have positive effects throughout the body, with the potential for new treatments for nonalcoholic fatty liver disease (NAFLD), Parkinson's, Alzheimer's, osteoarthritis, and chemical dependency. One study found evidence that low doses of semaglutide could reduce cravings for alcohol and called for further clinical trials of GLP-1s for alcohol use disorder.
Here’s more on how GLP-1s can affect your entire body, and why tracking body composition can be important for people taking them to ensure their weight loss is good for their total body health.
How GLP-1 medications work
GLP-1 is a naturally occurring hormone produced in your gut in response to eating food. It prompts the release of insulin, delays digestion, makes you feel full so that you stop eating, and delays when you feel hungry again.
GLP-1 medications mimic the effects of the naturally occurring hormone. They prompt insulin release from the pancreas, which is why they were originally approved to treat type 2 diabetes. But researchers noticed that GLP-1s had other effects, specifically on appetite regulation, hunger reduction, and satiation. Many have reported a decrease in their desire for high-fat, sweet, and other less-healthy foods. The ability of GLP-1s to lower cravings, decrease desired portion size, and increase time between meals has made them ideal for treating obesity, which also lowers risk for other serious conditions, including cancer and cardiovascular disease.
You probably know GLP-1s by one of their brand names. The three approved by the FDA for obesity are Wegovy (semaglutide), Zepbound (tirzepatide), and Saxenda (liraglutide). Wegovy is also approved for preventing heart attacks or strokes in adults with cardiovascular disease. And four are approved for diabetes: Ozempic (semaglutide), Rybelsus (semaglutide), Victoza (liraglutide), and Mounjaro (tirzepatide). Additionally, Ozempic (semaglutide) was FDA approved in February 2025 to reduce the risk of worsening kidney disease, kidney failure, and death due to cardiovascular disease in adults who have chronic kidney disease and type 2 diabetes.
Both semaglutide and tirzepatide target the brain to curb hunger signals, and most people taking GLP-1s feel fuller more quickly and for longer. Many users experience significant weight loss during the first 12 to 18 months while taking the drugs: between 10% and 15% of body weight on semaglutide, according to one study, and over 18% while on the highest dose of tirzepatide, according to another study.
How GLP-1s affect your body composition
For those struggling with obesity, the immediate promise of GLP-1s is their ability to help drive weight loss, lower cholesterol and blood pressure, and improve heart health. But there can be downsides to the rapid weight loss that can come from GLP-1s, notably the loss of lean muscle mass along with the loss of fat. According to a recent study in the American Journal of Lifestyle Medicine, 25% to 40% of the weight lost with GLP-1s might be from muscle mass.
That can be a major concern, according to award-winning, board-certified radiologist Dr. Jason Itri, VP of Body Imaging at Prenuvo, and the owner of Longevity Health Clinic in Charlottesville, Virginia. “Just like visceral fat is pro-inflammatory, more muscle is actually protective.” Because of this, Dr. Itri strongly suggests strength training to maintain and build muscle mass if you are taking GLP-1s, and to try to lose about one pound a week to ensure that you’re losing fat rather than muscle. “When I’m talking about exercise with patients, I emphasize that it does more than burn calories,” he says. “There's all kinds of beneficial effects of active muscles that are protective all throughout the body that help reduce inflammation and activate pathways that are anti-aging,” he explains further.
This is a key reason why Dr. Itri strongly suggests tracking your body composition if you are on GLP-1s. With a body composition analysis, you will have a better understanding of your body fat, muscle volume and symmetry, and abdominal organ volume. By using such a tool over the course of GLP-1 treatment for weight loss, you can see whether you are losing fat or muscle, giving you the opportunity to maintain or build back muscle before it’s too late. For tracking your progress, talk to your doctor about how often a body composition analysis might be necessary.
Related: What you get in a body composition report
In addition to muscle loss, GLP-1s may also affect bone health, particularly in older adults. University of Colorado researchers found an increased fracture risk in people over the age of 68 without diabetes using GLP-1s for obesity. They suggested that GLP-1-induced weight loss might contribute to fracture risk due to muscle and bone loss from reduced mechanical load. Yet another reason for maintaining a strength training routine.
How GLP-1s affect your heart
Dr. Itri also notes the many heart health benefits of GLP-1s, particularly in those using them for obesity. A recent study published in Frontiers in Clinical Diabetes and Healthcare backs up those claims, noting that in addition to promoting weight loss, GLP-1s can help decrease systemic inflammation, blood pressure, and cholesterol. In fact, according to the NY Times, cardiologists were among the earliest to take GLP-1s due to their ability to lower cholesterol.
But do the benefits outweigh any potential risks to the heart? A study from 2023 published in the journal Cureus, discusses that while research is still ongoing, studies to date have shown no increase in cardiovascular disease from GLP-1s. Another 2023 study in the Journal of Cardiac Failure noted that the effects on heart health varied depending on whether or not the person taking the drug had already experienced heart failure. Those who had not yet experienced heart failure had decreased risk of heart failure from GLP-1s, while those who had previously experienced heart failure might have increased risk for future heart failure events.
How GLP-1s affect your brain
Researchers are still discovering all of the ways in which GLP-1s affect your body beyond the heart, including what they do to the brain. New research from the University of Toronto identifies previously unknown relationships between the gut and the brain that could have profound effects on the suppression of peripheral inflammation.
In addition to reducing inflammation, GLP-1s have been found to improve cerebral blood flow and neurovascular function. Since chronic inflammation of the brain is one of the contributors to Alzheimer's, this is very good news, according to Dr. Itri.
However, GLP-1s may also have some potentially negative effects on the brain, particularly on mental health. A recent study showed serious mental health risks associated with GLP-1 treatment, including a 195% higher risk of major depression, a 108% increased risk for anxiety, and a 106% elevated risk for suicidal behavior. The study noted the critical importance of considering a complete patient history before prescribing GLP-1s and called for further clinical trials to examine the relationship between GLP-1s and the mental health of obese populations.
Related: 6 powerful brain exercises to help sharpen your mind
Other ways GLP-1s affect your body
GLP-1s delay gastric emptying, which has both pluses and minuses. According to The Lancet, their ability to slow digestion and delay bowel movements is part of how they help regulate blood sugar. But the downside is that your meals will sit in your gut longer. Not surprisingly, the main side effects of GLP-1s are most often gastrointestinal, with many reporting nausea, vomiting, diarrhea, constipation, acid reflux, stomach pain, and general gastric discomfort in the first few months of taking the drugs.
Your ability to benefit from GLP-1s may be tied to the microbiome of your gut. In a recent study published in Frontiers in Endocrinology, people responded differently to GLP-1s depending on their particular gut microbiota, with many seeing benefits and losing weight, and smaller numbers seeming to resist response to the treatment.
Many also benefit from the anti-inflammatory properties of GLP-1s. Inflammation is part of your body’s defense system against stimuli that could harm you, such as pathogens, toxic compounds, radiation, or damaged cells. Think of it as your immune system’s fight response. Chronic or systemic inflammation, however, is like an overload on your body’s immune system, and it can have serious effects on your mental and physical health. Conditions such as heart disease, stroke, cancer, diabetes, chronic kidney disease, non-alcoholic fatty liver disease (NAFLD), and autoimmune and neurodegenerative conditions are all related to chronic inflammation.
Anything you can do to lower inflammation in your body — such as losing visceral fat — will promote better health outcomes down the road, according to Dr. Itri. This is why understanding your body composition is so important in relation to GLP-1 treatment. “Differentiating muscle from fat, and subcutaneous fat from visceral fat, will give you a premonition of the future of what's going to happen while you still have the time to make the changes you need to make for better health,” he explains. A great way to better understand your fat and muscle levels is with a body composition analysis.
GLP-1s and future treatments for other conditions
Researchers are studying new ways that GLP-1s could be used in future treatments. Clinical studies are underway for:
- Nonalcoholic fatty liver disease (NAFLD), which affects up to 70% of people with diabetes. While there are currently no specific drugs approved for treatment, research is being done on how GLP-1s may be able to halt or even reverse NAFLD. Additionally, with a body composition analysis, you can track the status of your liver fat and whether it changes over time.
- Parkinson’s, a neurodegenerative disorder that causes progressively worsening tremors, muscle rigidity, and other movement-related symptoms. Research has shown some positive results from GLP-1s in benefitting both motor skills and emotional well-being in those with the disease.
- Alzheimer’s, the most common cause of dementia, which causes progressive cognitive decline, memory impairment, personality changes, and motor skill decline. Research is being done into whether GLP-1s can drive improvements in the brain's glucose metabolism by improving glucose transport across the blood-brain barrier.
- Osteoarthritis, a degenerative joint condition affecting millions. Research shows potential for GLP-1s to help treat osteoarthritis due to their anti-inflammatory, immunoregulatory, and differentiation properties.
- Chemical dependency, specifically addiction to alcohol, cigarettes, or other drugs. Researchers are looking into whether GLP-1s might be able to inhibit the dopaminergic release in the brain's reward centers from chemical use in a similar way to its effects on food cravings. GLP-1s have shown promise in decreasing withdrawal effects and reducing alcohol consumption — the same study also noted lower cigarette use in current smokers.
Being proactive while taking GLP-1s
According to Dr. Itri, GLP-1s can be the boost that some people need to help them make lifestyle changes that can stick. “We can't just rely on the medication,” he says. “What’s so great about GLP-1s is that they make it easy, but it’s got to be a lifestyle change too, and things like diet and exercise,” he explains.
If you are thinking about taking a GLP-1 medication, be sure to talk to your doctor. Realize that it won’t be a “magic bullet,” and that you will still need to make dietary changes and develop an exercise regimen to maintain your lean muscle mass. And, by tracking your body composition, you can keep a close eye on the progress you make.
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