Eating well on a GLP-1: protein, fiber, fluids and muscle

GLP-1 medicines such as semaglutide (Wegovy), tirzepatide (Zepbound) and orforglipron (Foundayo) change hunger, fullness and cravings, and in studies, people on these medicines ate 16% to 39% fewer calories than people on placebo [1]. When you’re eating less, each bite counts for more.

This guide covers the basics: protein, fiber, fluids, nausea, alcohol and keeping your muscles strong. It isn’t a diet plan. If you have diabetes, kidney disease or another health condition, ask your clinician whether you need to adapt this general advice [2].

Why nutrition matters on a GLP-1

A 2025 joint advisory from four professional societies in lifestyle medicine, nutrition and obesity care names the main nutrition challenges with these medicines: digestive side effects, nutrient shortfalls from eating less, and loss of muscle and bone [1]. Some of the weight people lose is lean mass, including muscle (see what the trials show). The advisory says good nutrition and exercise can help reduce these problems. Building habits now may also make them easier to keep if you ever stop the medicine [1]. Read more about stopping a GLP-1.

Make protein a priority

Protein helps build and maintain muscle and bone [3]. The 2025–2030 Dietary Guidelines for Americans set a goal of 1.2 to 1.6 grams of protein per kilogram of body weight a day, adjusted to your calorie needs [2].

For people with obesity, experts aren’t sure which weight to use in that math, because using your full body weight can overestimate how much protein you need. One simpler option the joint advisory describes is a set target of 80 to 120 grams a day. It also advises against eating 2 grams per kilogram or more for long periods [1]. Ask your clinician or a dietitian what goal fits you.

Tips that may help:

• Eat the protein part of your meal first [1].
• Choose protein foods that are easy to eat in small amounts, such as fish, eggs, Greek yogurt, cottage cheese, nuts and seeds, or nut butters [1].
• Get protein from a variety of foods, such as poultry, seafood, eggs, dairy, beans, peas, lentils and soy [2].

Protein alone likely isn’t enough to protect your muscles; the advisory says it should be paired with strength training (see below) [1]. If you have kidney disease, you may need a different amount of protein, so work out the right balance with your care team [3].

Build meals around plants and whole grains

Fruits, vegetables, whole grains, beans, nuts and seeds are good sources of fiber [4, 5], and the joint advisory names them among the nutrient-rich, minimally processed foods to emphasize [1]. Both the advisory and the Dietary Guidelines suggest limiting highly processed foods, refined grains, added sugars and sugary drinks [1, 2]. The Guidelines suggest about 3 servings of vegetables and 2 of fruit a day on a 2,000-calorie pattern, plus 2 to 4 servings of whole grains, all adjusted to your calorie needs [2].

Fiber: go slowly

Fiber helps prevent constipation [4], one of the most common side effects of these medicines [6, 7, 8]. Adults should get 22 to 34 grams of fiber a day, depending on age and sex [5]. Add it a little at a time, because increasing fiber too quickly can cause gas, bloating and cramps [4, 5]. In the first few days of treatment, avoiding fatty or high-fiber foods may ease nausea [1].

Drink enough fluids

Nausea, vomiting and diarrhea can make you lose fluids. That can lead to dehydration, which may cause kidney problems, so the FDA labels for these medicines stress drinking fluids [6, 7, 8]. Fluids also help fiber work against constipation [5].

• Choose water (still or sparkling) and other unsweetened drinks [2].
• Ask your clinician how much to drink each day, since needs differ [9].
• If it’s hard to keep liquids down, drink small amounts of clear liquids often, or try small sips of water or ice chips [9, 10].
• Watch for signs of dehydration: feeling very thirsty, a dry mouth, urinating less, dark urine, or feeling tired or dizzy [9].

If you take Wegovy tablets, follow the label: take the tablet on an empty stomach in the morning with no more than 4 ounces of plain water, then wait 30 minutes before eating, drinking or taking other pills [6]. Foundayo can be taken with or without food [8].

Eat slowly and stop when you’re full

These medicines slow how fast your stomach empties, which can cause fullness, bloating and nausea [1, 6]. Eating slowly gives your brain time to realize your stomach is full, which may take at least 15 minutes. Stop eating when you’re full [11, 12].

Digestive side effects are generally more likely when you start the medicine or raise the dose [1] (see starting a GLP-1). Other habits that can help:

• Eat smaller meals more often. Large meals make vomiting more likely [1].
• Don’t go too long without eating. Skipping meals because of nausea can make nausea worse. A small breakfast, then small meals every 3 to 4 hours, may help [1].

Foods that can make nausea worse

Triggers differ from person to person [13]. Common ones include:

• Fatty or greasy foods [1, 10, 13]
• Spicy or salty foods [10, 12]
• Fizzy drinks and alcohol [12, 13]
• Large portions [1]
• Strong smells [10]

Bland foods may sit better [10]. Soups and smoothies made with fruit and yogurt or milk can be easier to manage than heavy foods, and ginger or peppermint tea helps some people [1]. For more, see GLP-1 side effects.

Go easy on alcohol

The 2025–2030 Dietary Guidelines advise drinking less alcohol for better health. They say some people should avoid it completely, including those who are pregnant or take medicines that interact with alcohol [2]. With a GLP-1 medicine, there are more reasons to limit it:

• Alcohol can worsen nausea and acid reflux, and the joint advisory recommends keeping it to a minimum [1]. The UK’s National Health Service says it’s best not to drink while taking semaglutide or tirzepatide, because alcohol can increase nausea and vomiting [14, 15].
• Heavy drinking is one of the most common causes of pancreatitis (inflammation of the pancreas) [16], which the FDA labels for these medicines also warn about [6, 7, 8].
• If you take insulin or a sulfonylurea (a type of diabetes pill that raises insulin), drinking too much alcohol without enough food can cause low blood sugar. If you drink, it’s safer to eat some food at the same time [17].

Keep your muscles strong

The Physical Activity Guidelines for Americans recommend that adults:

• Get 150 to 300 minutes a week of moderate aerobic activity, such as brisk walking, spread through the week [18].
• Do muscle-strengthening activities that work all major muscle groups on 2 or more days a week. Examples include lifting weights, using resistance bands, push-ups, climbing stairs and carrying heavy groceries [18].
• Move more and sit less. Some activity is better than none [18].

For people on GLP-1 medicines, the joint advisory goes further. It suggests strength training at least three times a week plus at least 150 minutes of moderate aerobic exercise to help preserve muscle and bone. Aerobic activity alone does less to preserve lean mass during rapid weight loss [1].

If you’re not active now, “start low and go slow” and build up gradually. If you have a health condition, ask your clinician what types and amounts of activity are right for you [18].

Do you need supplements?

You can usually get all the vitamins you need from food, and a varied diet is the best way to do it [19]. But eating much less can leave gaps [1]. The joint advisory suggests that clinicians check for shortfalls and consider supplements for nutrients you’re at risk of running low on, such as vitamin D, calcium or vitamin B12, or a multivitamin with minerals, at doses tailored to you [1].

Ask your clinician before starting a supplement, because high doses of some vitamins can cause problems [19]. Tell them if you notice possible signs of a shortfall, such as unusual tiredness, a lot of hair loss, flaky or itchy skin, muscle weakness, slow wound healing or unusual bruising [1].

When to see a dietitian

A registered dietitian can help you find an eating pattern that meets your nutrition goals and fits your needs and preferences [1]. The joint advisory says dietitian counseling alongside a GLP-1 can help with digestive side effects, especially when starting or raising the dose, and with getting enough nutrients [1]. It may be especially useful if:

• You’re eating very little, skipping meals or struggling with nausea [1].
• You have diabetes, kidney disease, celiac disease or another condition that affects what you should eat [1, 2, 3].
• You’ve had bariatric surgery, followed a very low-calorie diet or had a nutrient deficiency before [1].

If you’ve ever had an eating disorder, tell your clinician before starting a GLP-1. The advisory recommends referral to an obesity medicine specialist and an eating disorder specialist first [1].

When to get medical care

Call 911 if you have chest pain, trouble breathing, or swelling of your face, lips, tongue or throat. Trouble breathing and swelling can be signs of a serious allergic reaction [6, 7, 8].

Call your clinician right away or get same-day care if you have:

• Severe stomach pain that won’t go away, with or without vomiting. The pain may spread to your back. This can be a sign of pancreatitis [6, 7, 8].
• Pain in your upper stomach, fever, yellow skin or eyes, or clay-colored stools, which can be signs of gallbladder problems [6, 7, 8].
• Nausea, vomiting or diarrhea that won’t go away, vomiting that lasts more than 24 hours, or blood in your vomit [6, 10].
• Signs of dehydration, such as dark urine, urinating less than usual or dizziness. Get help right away for confusion, fainting, a rapid heartbeat or not urinating at all [9].
• Signs of low blood sugar if you take insulin or a sulfonylurea, such as shakiness, sweating, dizziness or confusion [6, 7, 8].

The bottom line

When a GLP-1 medicine cuts your appetite, what you do eat matters more. Aim for enough protein, plenty of plants and whole grains, and steady fluids, and add fiber slowly [1, 2, 5]. Eat slowly, stop when you’re full, and go easy on alcohol and greasy foods [1, 11, 12]. Pair protein with regular strength training to help protect your muscles [1, 18]. You can usually get the vitamins you need from food, but ask your clinician or a dietitian about gaps, and check before starting any supplement [1, 19].

References

1. Mozaffarian D, et al. Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. Obesity. 2025. https://pubmed.ncbi.nlm.nih.gov/40445127/
2. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2025–2030. USDA and HHS. 2026. https://cdn.realfood.gov/DGA.pdf
3. National Institute of Diabetes and Digestive and Kidney Diseases. Healthy eating for adults with chronic kidney disease. National Institutes of Health. 2025. https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/eating-nutrition
4. MedlinePlus. Dietary fiber. U.S. National Library of Medicine. 2023. https://medlineplus.gov/dietaryfiber.html
5. National Institute of Diabetes and Digestive and Kidney Diseases. Eating, diet, & nutrition for constipation. National Institutes of Health. 2018. https://www.niddk.nih.gov/health-information/digestive-diseases/constipation/eating-diet-nutrition
6. Novo Nordisk. Wegovy (semaglutide) injection and tablets: prescribing information and medication guide. DailyMed, U.S. National Library of Medicine. Label revised June 2026 (effective June 18, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b
7. Eli Lilly and Company. Zepbound (tirzepatide) injection: prescribing information and medication guide. DailyMed, U.S. National Library of Medicine. Label revised August 2026 (effective August 28, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=487cd7e7-434c-4925-99fa-aa80b1cc776b
8. Eli Lilly and Company. Foundayo (orforglipron) tablets: prescribing information and medication guide. DailyMed, U.S. National Library of Medicine. Label revised July 2026 (effective July 29, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8ac446c5-feba-474f-a103-23facb9b5c62
9. MedlinePlus. Dehydration. U.S. National Library of Medicine. 2023. https://medlineplus.gov/dehydration.html
10. MedlinePlus. Nausea and vomiting. U.S. National Library of Medicine. 2024. https://medlineplus.gov/nauseaandvomiting.html
11. National Institute of Diabetes and Digestive and Kidney Diseases. Food portions: choosing just enough for you. National Institutes of Health. 2021. https://www.niddk.nih.gov/health-information/weight-management/just-enough-food-portions
12. Sievenpiper JL, et al. Nutritional and lifestyle supportive care recommendations for management of obesity with GLP-1-based therapies: an expert consensus statement using a modified Delphi approach. Obesity Pillars. 2025. https://pubmed.ncbi.nlm.nih.gov/41502845/
13. National Institute of Diabetes and Digestive and Kidney Diseases. Eating, diet, & nutrition for indigestion. National Institutes of Health. 2025. https://www.niddk.nih.gov/health-information/digestive-diseases/indigestion-dyspepsia/eating-diet-nutrition
14. NHS. Semaglutide: a medicine to manage type 2 diabetes or treat obesity. NHS website. 2026. https://www.nhs.uk/medicines/semaglutide/
15. NHS. Tirzepatide: a medicine to manage type 2 diabetes and treat obesity. NHS website. 2026. https://www.nhs.uk/medicines/tirzepatide/
16. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & causes of pancreatitis. National Institutes of Health. 2017. https://www.niddk.nih.gov/health-information/digestive-diseases/pancreatitis/symptoms-causes
17. National Institute of Diabetes and Digestive and Kidney Diseases. Low blood glucose (hypoglycemia). National Institutes of Health. 2021. https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia
18. U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition. HHS. 2018. https://odphp.health.gov/sites/default/files/2019-09/Physical_Activity_Guidelines_2nd_edition.pdf
19. MedlinePlus. Vitamins. U.S. National Library of Medicine. 2024. https://medlineplus.gov/vitamins.html

This article is for education only and isn’t a substitute for advice from your own clinician.