GLP-1 Medications and Diet: Why Protein Matters During Your Weight Loss Journey 

Jorge Quintana, DHSc, MPH, COML, CHES®

 

You know how you can feel full after eating a good meal and you’re not thinking about food right away? That's protein at work!

 

Protein matters because it helps your body work properly or when appetite is reduced, such as when on GLP-1 medications. 

 

GLP-1 (glucagon-like peptide-1) is a natural hormone in the body that helps you regulate appetite and blood sugar. GLP-1 medications are designed to work just as this natural hormone, helping you feel full sooner, slowing how quickly you digest your food, and reducing your overall appetite and cravings, which results in weight loss.  

 

This guide answers questions you may have about protein intake while taking GLP-1 medications, helping you during weight loss journey. 

 

What is a GLP-1 medication?

GLP-1, or glucagon-like peptide-1 medications, are a type of treatment that help with weight loss by reducing appetite and slowing digestion. Research shows that they work by curbing your appetite, reducing any cravings you may have throughout the day for snacking, and helping you feel full a lot faster. As a result, people often eat less and lose weight, mostly from body fat.

 

Why does protein matter while I am on this medication?

While you may reduce body fat while losing weight, your body may also lose some muscle. Clinical studies show that most weight loss includes a mix of fat and lean mass. Muscle is important for strength, metabolism, and overall health, so it’s important to protect it. Research suggests that eating enough protein can help preserve muscle while your body is losing weight.

 

How does protein help preserve muscle mass?

Muscle is made of protein. When you are eating less, your body may break down the muscle it has for its own energy. Protein helps preserve muscle because your body uses protein to build and maintain muscle. This is why eating enough protein will help your body hold on to its muscle while losing weight. 

 

Why is muscle mass important if I am losing weight on this medicine?

It is expected that your body will lose some lean mass during weight loss, but preserving it is still very important. Muscle affects your strength, metabolism, and overall health. 

 

How will I know if I am losing muscle mass rather than fat?

Because weight loss includes both a mix of body fat and muscle mass, it is not easy to tell, especially early on. As you start your treatment, pay attention to your strength, energy level, or how your body feels after daily activities, which could be indicators that muscle is being affected. Research shows that focusing on eating enough protein and staying active, especially with strength-based movement, can help protect muscle as you lose weight.

 

How much protein should I consume daily?

Research suggests that higher protein intake may help preserve muscle during weight loss, especially when you are eating less as a result of being on the GLP-1 medication. It is generally recommended to include a protein source in every meal. On average, the protein source should have about 20-30 grams, but the needs of every individual may be different based on body, health, and activity level. Check in with your healthcare provider or dietitian to find the right amount for you. 

 

What are good protein sources I should focus on, especially as I start noticing a decrease in appetite?

Good sources of protein include lean meats such as fish, chicken, or turkey as well eggs and some dairy products such as yogurt and cottage cheese. There are also plant-based options such as beans and nuts. 

 

Because your appetite will be low and you will feel full a lot faster, it may be helpful to try smaller portions of protein-rich foods throughout the day. 

 

What sources of protein will help minimize the side effects I may experience from this medication? 

If you start to experience side effects, it may be helpful to eat simple and small protein-rich foods that will be gentle on your stomach. Clinical guidance suggests foods such a protein shake, yogurt, cottage cheese or small portions of chicken and fish can be easier to tolerate. Avoid fried, greasy, or spicy foods that may make the side effects worse. Paying attention to what feels comfortable for your body and adjusting as needed can help you stay consistent with your nutrition. Always keep your medical provider updated with the side effects that you are experiencing. 

 

GLP-1 medications can be an effective treatment for weight loss. As you lose weight, it is important to pay attention to your nutrition, especially protein, to protect your muscle mass and therefore your overall health. Choosing simple, protein-rich foods can help you on your journey. Always keep your medical provider updated on how your body is responding to the treatment. 

 

References:

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Cava E, Yeat NC, Mittendorfer B. Preserving Healthy Muscle during Weight Loss. Adv Nutr. 2017 May 15;8(3):511-519. doi: 10.3945/an.116.014506. PMID: 28507015; PMCID: PMC5421125.

 

Leidy HJ, Clifton PM, Astrup A, Wycherley TP, Westerterp-Plantenga MS, Luscombe-Marsh ND, Woods SC, Mattes RD. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015 Jun;101(6):1320S-1329S. doi: 10.3945/ajcn.114.084038. Epub 2015 Apr 29. PMID: 25926512.

 

Rossi G, Bucciarelli L, Mananguite CL, Giovarelli M, Fiorina P. Muscle loss and GLP-1R agonists use. Acta Diabetol. 2026 Feb;63(2):333-342. doi: 10.1007/s00592-025-02611-2. Epub 2025 Nov 7. PMID: 41201615; PMCID: PMC12957034.

 

Tinsley GM, Heymsfield SB. Fundamental Body Composition Principles Provide Context for Fat-Free and Skeletal Muscle Loss With GLP-1 RA Treatments. J Endocr Soc. 2024 Sep 25;8(11):bvae164. doi: 10.1210/jendso/bvae164. PMID: 39372917; PMCID: PMC11450469.