Why working with a Registered Dietitian Nutritionist (RDN) matters if you're using GLP-1 medications
If you are using-or considering using- a GLP-1 (glucagon-like peptide-1) medication such as Wegovy, Ozempic, Rybelsus, Victoza, Saxenda, Trulicity, Mounjaro, Zepbound, or another compounded version, working with a registered dietitian nutritionist (RDN) is not just nice to have; it’s often essential.
Why? Because GLP-1 medications change more than just your weight.
A recent clinical review reports weight loss ranging from 5% to up to 18%. On top of weight loss, GLP-1s may improve metabolic parameters, including blood sugar, lipid levels, and blood pressure.
But these benefits come with trade-offs. GLP-1s often slow gastric emptying and reduce appetite. That means you might eat less and feel full longer. Over time, this can lead not only to fat mass loss but also to loss of lean body mass (muscle) and reductions in nutrient intake for both macro and micronutrients. In short, GLP-1s are powerful, but they fundamentally alter how your body experiences hunger, fullness, nutrient absorption, and overall energy balance.
What Working With a Registered Dietitian Adds (and why it is vital):
Baseline Assessment:
Before starting GLP-1 therapy, a Registered Dietitian Nutritionist (RDN) can conduct a comprehensive baseline assessment to establish a strong foundation for care. This includes evaluating current eating patterns, micronutrient status, body composition, muscle mass (using tools like an InBody machine), and individual risk factors.
Expert guidelines identify this initial assessment as a critical first step in effective and sustainable GLP-1 care, helping ensure that treatment supports both metabolic health and long-term well-being.
Prevent Nutrient Deficiencies:
With reduced food intake, some vitamins and minerals may become insufficient over time, particularly if intake drops below certain calorie thresholds. For example, lower intake of calcium, magnesium, iron, B vitamins, vitamin D, and protein has all been noted among GLP-1 users in observational studies.
An RDN helps ensure that even with smaller portions, your nutrition remains adequate and balanced. They can assess dietary gaps, prioritize nutrient-dense foods, and recommend appropriate supplementation when needed.
Safeguard Muscle and Bone Health:
Rapid or substantial weight loss can lead to loss of lean mass (muscle) and bone mass. An RDN can help design a wellness plan to preserve lean body mass- a key factor for metabolic health, strength, and long-term weight maintenance.
Manage Gastrointestinal Side Effects:
Due to slowed gastric emptying, many people starting GLP-1 therapy experience GI issues such as nausea, constipation, bloating, or delayed digestion. An RDN can tailor meal timing, portion sizes, food textures, hydration, and nutrient density to minimize discomfort while still meeting nutritional goals.
Support Behavior Change for Long-Term Success:
The clinical trials that led to the approval of GLP-1 medications did not rely on the medication alone. Participants also received structured lifestyle support, including calorie-reduced nutrition plans, physical activity, and regular counseling. When nutrition and lifestyle changes are not integrated, the benefits of GLP-1 therapy may be limited or difficult to sustain.
According to a joint advisory from leading organizations, including the Obesity Medicine Association and The Obesity Society, GLP-1s pose multiple challenges when used in isolation. The risks include GI side effects, nutrient deficiencies, muscle and bone loss, low long-term adherence, and potential weight regain.
In short, the most significant and sustained weight loss outcomes in GLP-1 trials occurred when nutrition support was part of the treatment protocol. This underscores the importance of structured nutrition and lifestyle intervention alongside medication, rather than relying on the medication alone.
If you are considering starting a GLP-1, or are currently using one and want to reduce side effects or prevent weight regain, working with a Registered Dietitian Nutritionist can be an important part of your care.
Our RDNs can partner with you to build sustainable habits that support long-term health and success. Reach out to schedule an appointment and learn more about how we can help!