A Dietitian's Guide to Nutrition and GLP-1 Therapy
- Michael Glab MS, RD, LDN
- 46 minutes ago
- 7 min read
GLP-1 medications are currently all the rage in healthcare. These injectable medications are helping people eat less, lose weight and improve their overall health! In order to get the maximum potential out of these medications, it's critical to adapt your eating habits to deal with the main side effects of taking a GLP-1 (reduced appetite, nausea, diarrhea or constipation) to ensure positive and lasting results. In this blog post, we explain how to be intentional with your nutrition when you’re on a GLP-1.
What Are GLP-1 Medications?
GLP-1 receptor agonists (like semaglutide or tirzepatide) are medications that mimic a natural hormone called glucagon-like peptide-1. They help regulate blood sugar, slow digestion, and signal fullness, which is why many people experience a reduced appetite and weight loss.
However, while these medications make eating less easier, they can also make eating enough of the right things more challenging. This is especially true in the hours or even days after taking your injection or when you move up the dosage. That's where nutrition plays a key role.
Why Nutrition Still Matters
When your appetite changes, your body still needs the same essential nutrients just in smaller, smarter portion sizes. Research shows that people using GLP-1 therapy can unintentionally eat too little protein, fiber, or micronutrients (like calcium, magnesium, and vitamins A, D, E, and K) as appetite and total food intake decrease.
In fact, the American Journal of Clinical Nutrition’s 2025 consensus paper found that pairing these medications with targeted nutrition and exercise is critical to preserve lean muscle mass, maintain gut health, and achieve and maintain long term results.
Here’s How Nutrition Helps You Get the Most Out of Your Medication:
1) Prioritize Protein
GLP-1s reduce appetite and with less food, you risk losing muscle along with fat. Studies show that a higher protein diet helps preserve lean body mass, which supports metabolism and long term weight maintenance.
➜Try this: When your appetite is good, aim for 20-30 grams of protein at each meal and 10 grams or more at snacks to help preserve lean muscle and keep you feeling satisfied. That's roughly:
3-4 oz cooked chicken, fish, or lean beef (~25-30 g or what can fit in the palm of your hand)
¾ cup Greek yogurt (~15g)
2 eggs + 1 oz cheese (~18 g)
¾ cup lentils or beans (~12–15 g)
1 scoop protein powder or shake (~20–25 g)
½ cup cottage cheese + ¼ cup nuts (~20 g)
If your appetite is not good, do your best to at least get a couple bites of protein. You can also try drinkable protein shakes or homemade smoothies. Homemade smoothies with a combination of protein powder, yogurt, fruit and greens are more nutritious than ready-to-drink (RTD) protein shakes due to the fact that you are consuming real ingredients. RTD protein shakes are good in a pinch when you're busy, but we do not suggest making them a regular replacement for the foods in the above list.
2) Get Fiber From Your Diet
Since GLP-1s slow stomach emptying, fiber can help regulate digestion, prevent constipation, and nourish your gut microbiome.
➜Try this: Start with about ½ cup of non-starchy vegetables (fresh, frozen, or canned) at each meal-such as spinach, zucchini, peppers, carrots, or green beans.
You can repeat this process with other fibrous foods like whole grains like oatmeal or whole wheat bread, or starchy veggies like beans or corn or higher fiber fruits like berries or pears.
Again, do your best to eat at least a couple of bites and if your appetite is good, try eating the entire portion. If you find you can comfortably eat more, that’s great! If not, that’s okay too. Your appetite may still be adjusting as your body adapts to the medication. Even small portions of colorful veggies still contribute important fiber, vitamins, and minerals that support digestion and fullness.
Fiber supplements may be helpful as well, but again, you want to make dietary fiber (aka fiber from foods) your priority.
3) Choose Healthy Fats
Monounsaturated and omega-3 fats (from olive oil, nuts, seeds, avocado, and fatty fish like salmon or tuna) help reduce inflammation and support heart and brain health.
➜Try this: Add about 1 teaspoon of olive oil to cooked vegetables or salads for healthy fats, or include a small portion of around 10–20 almonds (¼ cup) as a snack. You can also try adding ⅓ of an avocado (sliced or cubed) on top of a salad or whole grain toast.
These modest amounts still provide valuable unsaturated fats that support heart health and help you stay satisfied, even when your portions are smaller.
4) Stay Hydrated
Since GLP-1s slow digestion, you may not feel as thirsty as you did before GLP-1 therapy. Drinking water supports regular bowel movements and optimal functioning of the body.
➜Try this: Aim for small, frequent sips of water throughout the day rather than large amounts all at once. Again, try your best as some days it may be easier than others to consume fluids than others. If you can hit 64 oz of fluid (8 cups) probably the bare minimum, but you may need more if you notice your urine is darker yellow during the day. If plain water is unappealing, try herbal tea, fruit-infused water, or diluted electrolyte beverages to help you stay hydrated. You can also try adding flavor drops to your water to give it a boost.
Many GLP-1 users find it easier to drink between meals instead of with meals, since fluids can contribute to early fullness or nausea.
5) Move to Maintain Muscle
Weight loss from GLP-1 therapy may lead to muscle loss due to rapid weight loss and inactivity. Resistance exercise combined with consistent protein intake helps protect lean tissue and keeps your metabolism strong.
➜Try this: Aim for strength training at least 2 times per week, but ideally 3 or more times a week (or every other day on average). Start by spending about 20–30 minutes per session on major muscle groups (legs, back, chest and arms). If you can increase the amount of time per session and the amount of weight you are lifting gradually, this will be very beneficial for protecting lean mass long-term.
Body weight movements (like squats or push-ups), resistance bands, or light free weights are also great options. Even short, consistent sessions (10 minutes or less) can help preserve muscle and keep your metabolism strong while on GLP-1 therapy.
6) Eat Mindfully and Make Every Bite Count
When appetite signals may feel “muted”, learning to eat slowly and stop at comfortable fullness becomes key. Chew thoroughly and put the fork down between bites. Again, you may find it beneficial to drink water and fluids between meals instead of during meals, so the fluids don't cause you to feel full early.
Since food portions are now smaller, food quality matters more. Focus on balanced meals that include sources of protein, fiber, healthy fats and color from veggies to keep you nourished, even with less total intake.
If you’re feeling nauseous or have a low appetite, that’s okay! Even just taking a bite or two of each group helps you get critical nutrients. Eat what you can tolerate! You can also try to focus on soft, protein-rich foods (like Greek yogurt, cottage cheese, eggs, or homemade smoothies) until your appetite improves.
When your appetite is good, aim for:
20–30 grams of protein per meal (about 3–4 oz cooked chicken, fish, tofu, or lean beef - a palm of hand size portion)
½ cup of whole grains or starchy vegetables (quinoa, brown rice, sweet potato)
½ cup of non-starchy vegetables (roasted broccoli, peppers, spinach, or carrots)
1 teaspoon of healthy fat, like olive oil or avocado
Example: Grilled salmon (palm of hand size portion ) + ½ cup roasted vegetables + ½ cup quinoa + drizzle of olive oil
Nutrition + Medication = Your Best Results
GLP-1 therapy is a game-changer for many people as it helps them eat less. The medication helps regulate appetite and improve metabolic function as a result of weight loss. Nutrition determines how your body responds to those changes. To get the full potential of the GLP-1, healthy and consistent eating habits are vital!
As your appetite decreases, it becomes more important than ever to make each bite count. A balanced nutrition plan supports:
Preservation of lean muscle mass, which helps maintain metabolism and long-term weight stability.
Adequate micronutrient intake, reducing the risk of deficiencies as total food intake drops.
Digestive comfort and tolerance, by managing side effects such as nausea, diarrhea or constipation through dietary strategies.
Sustainable lifestyle habits, ensuring that progress lasts beyond medication use (if you plan on discontinuing the medication or if you experience gaps in therapy due to medication shortages).
Key Takeaways for Clients on GLP-1 Therapy:
Nutrition and GLP-1 Therapy work best together- medication regulates appetite, while nutrition can help preserve muscle and micronutrient status.
Proper protein intake (~20-30 g/meal) supports lean mass and long term weight maintenance.
Fiber rich, plant forward meals promote digestive health and satiety.
Hydration and mindful eating can help manage side effects like early satiety, nausea or constipation.
Resistance training complements nutrition to protect metabolic rate and preserve muscle.
If you need nutrition support while on GLP-1 therapy, please feel free to book an information session by clicking the “BOOK” button in the top right corner of the screen. Most insurance plans we accept cover our services 100%!
Thank you to our intern Rose Nigri for putting this blog post together!
Resources:
Mozaffarian, D., Agarwal, M., Aggarwal, M., Alexander, L., Apovian, C. M., Bindlish, S., ... & Callahan, E. A. (2025). 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 Pillars, 100181.
Christensen, S., Robinson, K., Thomas, S., & Williams, D. R. (2024). Dietary intake by patients taking GLP-1 and dual GIP/GLP-1 receptor agonists: a narrative review and discussion of research needs. Obesity Pillars, 11, 100121.
Neeland, I. J., Linge, J., & Birkenfeld, A. L. (2024). Changes in lean body mass with glucagon‐like peptide‐1‐based therapies and mitigation strategies. Diabetes, Obesity and Metabolism, 26, 16-27.
Johnson, B., Milstead, M., Thomas, O., McGlasson, T., Green, L., Kreider, R., & Jones, R. (2025). Investigating nutrient intake during use of glucagon-like peptide-1 receptor agonist: A cross-sectional study. Frontiers in Nutrition, 12, 1566498.
Watkins, J. D., Koumanov, F., & Gonzalez, J. T. (2021). Protein-and calcium-mediated GLP-1 secretion: a narrative review. Advances in Nutrition, 12(6), 2540-2552.
Miguéns-Gómez, A., Casanova-Martí, À., Blay, M. T., Terra, X., Beltrán-Debón, R., Rodríguez-Gallego, E., ... & Pinent, M. (2021). Glucagon-like peptide-1 regulation by food proteins and protein hydrolysates. Nutrition Research Reviews, 34(2), 259-275.
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