What to Eat & Drink When Taking Weight-Loss Medications

The National Institutes of Health reports that about 1 in 3 U.S. adults are overweight, and 2 in 5 are obese. With this many Americans struggling with their weight, it’s no wonder the National Health and Nutrition Examination Survey shows that, on average, nearly half of American adults are trying to lose weight. 

It’s no secret that weight loss is big business. But in the sea of fad diets and questionable weight-loss products, there are also valid and science-backed prescription medications that aid in weight loss for those who struggle with obesity and weight-related health conditions. Some of the common weight-loss medications prescribed are liraglutide (Saxenda), naltrexone-bupropion (Contrave), orlistat (Xenical), phentermine, semaglutide (Wegovy) and tirzepatide (Mounjaro).

While weight-loss medications aren’t a substitute for healthy diet and exercise, they can be used as a tool to help improve the well-being of certain individuals with obesity. We spoke to registered dietitian nutritionists to get the facts on what to consider before taking these medications, as well as what you can eat and drink while using them. 

How Weight-Loss Medications Work 

Weight-loss medications all work slightly differently to help achieve the same goal of weight loss, says New York-based dietitian Nicole Rodriguez, RDN. These medications reduce the overall calories you consume or affect the absorption of certain nutrients, she says.

For example, Rodriguez explains that weight-loss drugs like liraglutide, phentermine, semaglutide and tirzepatide suppress appetite through modifying hormones related to hunger and fullness. On the other hand, other drugs, like orlistat, inhibit absorption of dietary fats. Instead of absorbing calories from fat, more fat passes into your bowel movements and is eliminated from the body.

Things to Consider Before Taking a Weight-Loss Medication 

It may sound alluring to take medication for weight loss, but that’s not a recommendation for everyone.  For instance, just because someone is in a larger body does not mean they are unhealthy. Likewise, just because someone is in a smaller body does not mean they are healthy.  

While health professionals often use the body mass index (BMI) classification of over 30 to classify someone as obese or over 25 BMI to classify someone as overweight, we know that BMI is not always a reliable measure of one’s health. (More on that here.) That said, if someone is in a larger body and experiencing health problems related to their weight (such as diabetes, cardiovascular disease, gout and other conditions, as noted by the National Institute of Diabetes and Digestive and Kidney Diseases) and has difficulty losing weight even after trying to change their diet and exercise, then weight-loss medications may be beneficial.

However, weight-loss medication alone is not the answer. A 2021 review in American Psychologist pointed out that people who take a weight-loss medication alongside lifestyle modifications lose more weight compared to relying on one strategy on its own. What’s more, medications also help counteract changes that normally occur during weight loss, like an increase in appetite, further supporting success. 

Thus, while weight-loss medications may offer support, they do not replace healthy habits. “It's important to recognize that each of these drugs will be enhanced by a balanced diet and appropriate physical activity,” says Rodriguez. “Since many of these medications work to suppress appetite, getting the most nutritional bang for your buck at each eating occasion is a sound strategy,” she says.

What to Eat and Drink When Taking a Weight-Loss Medication

There is no one-size-fits-all approach to planning your diet while taking weight-loss medication. Working with a registered dietitian nutritionist is one of the best ways to ensure your particular nutrient needs are being met during weight loss. However, consider planning your diet with these tips in mind. 

Prioritize Protein 

To say protein is kind of a big deal would be an understatement. Protein is essential to the functioning of every cell in the body, including bone, blood, cartilage, muscle and skin cells. Plus, protein serves as a building block for hormones, enzymes and vitamins. It is also crucial in helping to repair and restore lean muscle mass, which is key to success with any weight-loss regimen, says Rodriguez.

Protein needs differ based on your age, sex, height, weight and activity level. However, a general guideline is to aim for at least 20 grams of protein per meal, and up to 35 grams, suggests registered dietitian nutritionist Lauren Harris-Pincus, M.S., RDN, founder of NutritionStarringYOU.com and author of The Everything Easy Pre-Diabetes Cookbook. This amount can help limit the muscle loss that happens when you lose weight. 

Emphasize Produce  

Fruits and vegetables provide dietary fiber, vitamins, minerals and antioxidants that offer benefits that extend beyond weight loss. 

Fiber is especially key during weight loss. “Nearly 95% of Americans miss the mark on fiber goals, and it’s even more important to get that fiber in when taking these medications to help keep you regular,” says Harris-Pincus. “Stick to fiber from food versus supplements (when possible) since fiber-rich foods are a treasure trove of vitamins, minerals and health-promoting antioxidants and phytonutrients.”

Rodriguez recommends choosing nonstarchy vegetables. “If you haven't always done great on the vegetable front, proceed slowly with a plan to increase over time,” says Rodriguez. That’s because ramping up fiber intake too quickly can cause uncomfortable side effects like gas and bloating, which can also throw off your hunger and fullness cues. There are easy ways to fit more fiber into your day.

Focus on Whole Grains 

Repeat after us: you don’t have to cut out carbs—especially whole grains, which offer more fiber and can help with satiety compared to their refined counterparts. 

While recent reviews, including one published in 2019 in Nutrients, have suggested the need for randomized control trials to prove the weight-loss benefits of whole grains, a 2023 meta-analysis in The American Journal of Clinical Nutrition has demonstrated the benefits of incorporating whole grains as part of a healthy diet to prevent cardiovascular disease and death from any cause.

Include Dairy 

Unless you have a particular medical reason to avoid dairy (such as a milk allergy or lactose intolerance), there’s no need to eliminate dairy foods from your diet.

Dairy foods are packed with nutrition, including calcium and vitamin D. “​​Calcium and vitamin D are two nutrients of concern in the American diet. Dairy products are a fabulous source of these bone-protecting vitamins and minerals, as well as protein needed to support muscle growth and decrease muscle loss that can accompany weight loss,” says Harris-Pincus.

While there are many different dairy products on the market, Harris-Pincus recommends choosing dairy options that contain probiotics, like plain Greek yogurt or kefir, to promote gut health. And, for those who do not tolerate dairy, she recommends choosing nondairy substitutes that are fortified with calcium and vitamin D.

Stay Hydrated

Be sure to stay adequately hydrated. One reason? A frequent side effect of weight-loss medications is constipation. Harris-Pincus suggests drinking 2 to 3 liters of water throughout the day. 

When you sip matters, too. “Since meeting nutritional needs might already be a challenge due to appetite suppression from these medications, you may want to reconsider your hydration strategy.  If you're consuming three meals per day, you may benefit from consuming water away from meals. If smaller, more frequent meals are working better for you, consider small sips of water during your meal, taking care not to fill up on water,” says Rodriguez. 

Precautions and Considerations

Just as you would do your homework before taking any prescription medication, the same goes for taking weight-loss medications. Be aware of the side effects they may cause, like potential nutrient deficiencies of fat-soluble vitamins. Your doctor or registered dietitian may recommend taking supplements of certain vitamins, like A, D, E and K, when on medications like orlistat, says Rodriguez.

Other side effects can range from nausea and gastrointestinal changes (diarrhea or constipation) to increased blood pressure and heart rate, according to the NIDDK. Be sure you’re communicating these symptoms with your doctor, who may recommend taking additional medications or using at-home remedies like ginger tea to counteract side effects like nausea, says Rodriguez.  

While a balanced diet will help supply important vitamins and minerals, it won’t meet the totality of your nutrient needs if you aren’t eating enough. “Because your overall caloric intake goes down, the quality of foods you eat needs to improve to make sure your nutrient needs are met. That leaves less room for added sugars and ultra-processed foods that offer little nutrition,” Harris-Pincus says. Consider eating smaller, more frequent meals filled with nutrient-dense foods like lean proteins, nuts, fish, produce and healthy fats. 

The Bottom Line 

“It’s very important to recognize that weight-loss mediations are a powerful tool, yet they are only one piece of the complex weight-management puzzle. It’s critical to overall health to ensure that at least basic nutritional needs are met, including adequate protein, fiber, essential fatty acids, vitamins, minerals and water,” says Harris-Pincus.

While registered dietitian nutritionists agree there may be a place for weight-loss medications as an add-on therapy for weight loss, they should not be the only strategy. Health professionals advise to use these medications in conjunction with a balanced diet and fitness program to help patients improve the conditions that are associated with obesity. Working with health care professionals is crucial to achieving weight loss and improving your health.