The 5 Worst Things You Can Do While Taking a GLP-1 for Weight Loss

by Alice Oglethorpe
January 26, 2026

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Think about how it feels when you’re prescribed most medications. Your doctor or pharmacist gives you specific instructions to follow—“Take it in the morning with food,” or “Avoid eating grapefruit while on it,” that sort of thing—and you go on your merry way, feeling pretty confident you’re handling it correctly. But if you’ve started taking a GLP-1 to lose weight, you may be feeling a little lost, almost like you’re being left to figure things out on your own.

One reason is the increasing popularity of these medications being prescribed in a nonpersonal way. “These treatments have exploded online, and there are a million different websites you can access them from,” says Michael Glickman, MD, a physician in New York who is triple board-certified in family medicine, lifestyle medicine, and obesity medicine. “[The experience is] fully digital, and you aren’t seeing a provider in person—and maybe you’re never speaking to a provider at all.”

Even if you’re prescribed a GLP-1 during an in-person doctor’s appointment, you may not know which questions to ask to ensure you really understand the medication.

This opens the door to making mistakes—ones that could worsen your side effects, affect how much weight you’ll lose, or even cause new health issues. Read on for five of the top things doctors told SELF you definitely should not do while taking a GLP-1.

1. Overlooking the importance of nutrition

Will you still lose weight while eating mostly pizza, chicken nugs, and bowls of cereal? Probably. But you won’t be doing your health any favors. “When our appetite is reduced—and it can be quite significantly reduced on a GLP-1—it becomes even more important to have really good-quality nutrition when we do eat,” says Brianna Johnson-Rabbett, MD, an obesity-medicine physician and endocrinologist and the medical director of obesity medicine at the University of Nebraska Medical Center in Omaha. It makes sense: You’re likely eating less, but you still need to supply your body with the key nutrients it needs, so every bite matters.

Dr. Glickman recommends eating fresh foods rather than highly processed ones and prioritizing fiber-rich foods like fruits and veggies, as well as protein from sources like chicken, tofu, and eggs. This last nutrient is especially important when losing weight, since you’re shedding muscle along with fat. “If you aren’t eating enough protein, you can lose too much muscle mass,” says Dr. Glickman. While the exact amount of protein you should aim for is personal, some research suggests a daily intake of between one and 1.5 grams per kilogram of body weight to reduce your risk of losing muscle. That’s around 80 to 120 grams a day if you weigh 175 pounds.

Equally important as what to eat is what to avoid—namely, foods that are high in fat, as they can exacerbate common GLP-1 side effects, like nausea. “GLP-1s can slow down your GI tract, and fat tends to move more slowly through your GI tract anyway. [That's why] people find higher-fat foods to be triggering,” Dr. Johnson-Rabbett says. Foods that contain healthy fats, like olive oil and avocado, are still important to eat in moderation for the health benefits, but try to skip fried items, which tend to be harder for the GI tract to handle and offer little nutritional benefit.

2. Forgetting to strength train

You know how you should eat protein to help hold on to muscle while on a GLP-1? That same goal is why you should strength train too. “We don’t expect to lose zero muscle when we lose weight,” says Dr. Johnson-Rabbett. “But the goal is to maintain a healthy amount of lean mass.” Retaining muscle function is also a key benefit of strength training. “[Muscle function] is the health of your muscles and what that means in terms of your ability to be physically active and do all the things you want to do,” she says. Strength training improves both muscle mass and muscle function—a win-win.

Other forms of exercise are also important for preserving bone density (something else you can lose while taking a GLP-1), reducing abdominal fat, improving heart health, and more. A good weekly goal is 150 minutes of moderate-intensity aerobic exercise (like brisk walking or using the elliptical), two to three days of strength training, and some flexibility work (such as yoga).

3. Thinking you just need to put up with side effects

For some people GLP-1s can bring on some pretty unpleasant side effects, including nausea, vomiting, constipation, and stomach pain. But don’t just suffer silently or write those off as the cost of staying on the meds. “This is not a healthy way to approach these medications,” says Dr. Glickman. “If you’re constantly not feeling well, maybe you’re on a dose that’s too high or you’re not on the right medication. There are so many choices now that can be prescribed. If you’ve taken a medication for several months and you still don’t feel well, it might not be the right medication for you.”

Your doctor will also be able to clue you in on some diet tweaks that could help. For example, Dr. Johnson-Rabbett tells patients experiencing side effects to eat smaller portions than they’re perhaps used to; minimize high-fat foods; and consider whether other triggers, such as alcohol, carbonated beverages, and sweets, might be causing their symptoms. “Really watch your response to certain foods,” she says. “Some people may have more unusual triggers, so keeping a log can be helpful.” If you don’t bring up your side effects to your provider, you may never know what you could do to feel better.

4. Going up in dosage too quickly

Yes, there are recommended schedules that outline how long to stay at each dose before moving up to the next one, but not everyone needs to follow this guidance to a T. “There’s a lot of variability in response to medications, and some people respond well to the initial dose,” says Dr. Johnson-Rabbett. “You want to work with your clinician to really find that balance of an effective dose with minimal side effects.”

Two clues you’ve potentially gone too high: You have pretty severe side effects, or you forget to eat. “Some people take way too strong of a dose, and their appetite is effectively being turned off,” says Dr. Glickman. “That’s not something we want someone to experience. It’s normal to have an appetite, and if it gets too low, it leads to undereating, which can lead to insufficient nutrient intake and fatigue.” Keep the lines of communication open with your provider, letting them know how you’re feeling and what your hunger levels are like. That way they’ll be able to customize your dose increases to fit you.

5. Thinking of your GLP-1 as a short-term solution

The idea sounds good in theory: Take a GLP-1 until you reach your goal weight, then go off it and keep up with your healthy habits to maintain your new, lower weight. But that isn’t what doctors tell SELF they see in their practices. “These medications are designed for long-term use,” Dr. Glickman says. He explains that’s because GLP-1s don’t change the underlying factors that contribute to someone living in a larger body or with obesity. In other words, the same genetics, hormones, family history, and other biological factors that might predispose you to having more body fat don’t vanish because you took a GLP-1.

That helps explain why studies show that after stopping GLP-1 treatment, most people regain weight. “There are some people who maintain their weight without continuing the medication, but we don’t have big ways to predict that,” says Dr. Johnson-Rabbett. “Know that it’s not a failure of willpower if you regain weight after stopping the medications.” This is yet another reason why it’s so helpful to be open and honest with your doctor. Wish you could go off the meds? Your provider can help you come up with a research-backed maintenance plan, which could include slowly tapering off the medication and monitoring the impact on your weight.

As you can see it’s surprisingly easy to think you’re doing the right thing on a GLP-1 while inadvertently making an unhealthy mistake. To minimize the chances of that happening, get your medication from a clinician certified in obesity medicine, Dr. Johnson-Rabbett says, noting that folks can find qualified providers through the American Board of Obesity Medicine (ABOM). These providers have all completed additional training in treating obesity and using GLP-1s, so they can guide you on your journey, minimizing the risk of errors.