By: Megan Sabo, Dietetic Intern and Graduate Student at West Chester University of PA

Understanding GLP-1 Medications 

Glucagon-like peptide 1 (GLP-1) receptor agonists have been found to be strong tools for weight loss when combined with lifestyle therapy and behavior change.¹ They work mainly by reducing appetite, increasing satiety, and slowing gastric emptying. Clinical trials show that average weight loss is much larger when using these drugs as opposed to older weight loss drugs, but gastrointestinal (GI) side effects, potential weight regain if drug usage stops, access/cost, and individualized medical nutrition therapy (MNT) remain crucial considerations for safe, effective care.² Our goal is for both physicians and patients who are prescribed to GLP-1’s and other agonists for weight loss to understand how important it is to be seeing a registered dietitian (RDN) as a part of their care team during the course of use, as well as after stopping. 

GLP-1 receptor agonists, such as Ozempic, Trulicity, and Victoza, mimic the gut hormone glucagon-like peptide-1. This is a hormone our bodies naturally produce in the gut after we eat, and it helps control blood sugar levels by stimulating insulin release. These medications also help to slow digestion, and send us the “I’m full” signals to our brains, which helps to control food intake and appetite. While trials have shown that these medications are effective tools for weight loss and diabetes management, they also change how and what people eat.^1,3. This is why receiving MNT from an RDN is essential to ensuring that patients are meeting their nutrient needs, managing potential side-effects, and building sustainable eating habits alongside medication use and after stopping medication use. 

Individual Responses to GLP-1 Medications and the Essential Role of RDNs

At Fit with Food, we’ve seen clients who have experienced a wide range of responses  to GLP-1 medication usage. As these medications have continued to rise in popularity, we know firsthand that nutrition guidance is most certainly not “one-size-fits-all.” These medications can influence hunger, digestion, and metabolism in different ways, meaning each client’s experience can look unique. Generally speaking, each client has fit into one or multiple of the following categories: 

1. Strong Appetite Suppression

Some clients feel the appetite-suppressing effects of these medications very intensely. While this can support reduced caloric intake and weight loss, it can also make it challenging to meet daily protein, micronutrient, and energy needs. Dietitians can help clients create smaller-portioned, nutrient-dense meals and snacks to ensure they’re still fueling their bodies appropriately, despite a lower appetite. 

2. Loss of Lean Body Mass

When caloric intake drops too quickly, especially without adequate protein or resistance training, clients may experience unintentional muscle loss. Preserving lean muscle is essential for metabolism, strength, and long-term weight maintenance. Through proper MNT, dietitians can emphasize strategies like spreading protein intake evenly throughout the day and incorporating strength-based movement to protect muscle mass and prevent further loss. 

3. Misunderstanding the Mechanism of Weight Loss

Many clients initially believe the medication itself directly “causes” weight loss. In reality, these drugs work by mimicking the GLP-1 hormone as described previously, which affects satiety signals, insulin release, and gastric emptying. Helping clients understand this mechanism can empower them to take an active role in their progress and recognize that healthy eating patterns and lifestyle changes remain key to sustainable results.

4. GI Side Effects

Common side effects of these medications, such as nausea, vomiting, diarrhea, or constipation, can interfere with meal timing, food choices, and appetite. Dietitians can help clients manage these symptoms by adjusting portion sizes, meal frequency, and food textures while maintaining hydration, gut health, and proper nutrient intake overall. 

5. Improved Blood Sugar Control without Weight Loss

Some clients may not see major changes in weight, but do experience improved A1C levels and blood glucose stability. These outcomes can come across as discouraging to those who wish to see weight loss, but should be viewed as equally meaningful, especially for those who are managing diabetes. Dietitians encourage clients by highlighting that progress looks different for everyone through emphasizing improvements in health markers, energy levels, and overall wellbeing, not just the number on the scale. 

The Ongoing Importance of RDNs in GLP-1 Treatment

RDNs play a critical role in guiding individuals who are using GLP-1s by promoting sustainable eating habits and lifestyle changes that will help them maintain their results beyond usage of the medication. Individuals should understand that regular physical activity, a balanced diet of nutrient-dense, whole foods, and healthy habits are crucial for daily living, and GLP-1s are not ‘magic’ solutions for weight loss or diabetes management. Without the proper mindset and education, users may see weight regain, rising A1C levels, and other negative health consequences if they are not properly counseled by a nutrition professional. The work of dietitians via MNT provides the guidance, support, and personalized strategies necessary to improve outcomes, manage side effects, and build long-term, sustainable health habits.

Citations

1. Wilding JPH, Batterham RL, Calanna S. Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England Journal of Medicine. 2021;384(11):989-1002. doi:https://doi.org/10.1056/NEJMoa2032183
2. ‌Zheng Z, Zong Y, Ma Y, et al. Glucagon-like peptide-1 receptor: Mechanisms and Advances in Therapy. Signal Transduction and Targeted Therapy. 2024;9(1):1-29. doi:https://doi.org/10.1038/s41392-024-01931-z
3. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387(3):205-216. doi:https://doi.org/10.1056/nejmoa2206038

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