By Maddie Hays, MS, CNS

In recent years, GLP-1 therapy has exploded in popularity. Many individuals are taking semaglutide or tirzepatide to manage their blood sugar, weight, overall metabolic health, or all of the above. While there are many benefits to utilizing GLP-1 therapy, it’s not a “magic pill” for weight loss — there are several nutrition and lifestyle considerations for this patient population. It is important to be cognizant of protein and fiber intake, maintain or increase muscle mass, and mitigate side effects of the drug. These are all priorities for us as dietitians and nutritionists, and our role is to help our patients optimize health through small, sustainable habits.

How does GLP-1 therapy work?

These two drugs, semaglutide (Ozempic and Wegovy) and tirzepatide (Zepbound and Mounjaro), both work by affecting multiple organs and systems. Contrary to popular belief, they don’t just affect weight and blood sugar.

A GLP-1 drug acts on the following areas of the body…

• Brain: decreases appetite and “food reward” mechanisms, and reduces “food chatter” or preoccupation with food, as well as lowering neuroinflammation.
• Cardiovascular: improvements in endothelial function, meaning the system works better and more efficiently, and reducing inflammation and atherosclerosis risk.
• Liver: lowers fat deposition in the liver, improving insulin sensitivity, and lowering inflammation.
• Musculoskeletal: preserving lean muscle mass, improvements in mitochondrial function, and reducing bone resorption.
• Metabolic health as a whole: increasing insulin secretion, slowing the emptying of the stomach, and improved oxidation of fat.

As you can see, these drugs have widespread effects in the body! This is a big reason why they are so transformative for metabolic health, weight reduction, and body composition.

Some statistics report that taking a GLP-1 drug will decrease an individual’s overall caloric intake by 16-39%. This is primarily why so many patients see such drastic weight changes after they begin taking the medication. But, as mentioned, this is only one part of the GLP-1 picture.

What are the side effects of GLP-1 therapy?

When starting a GLP-1 medication, most people will experience some form of nausea, diarrhea, constipation, abdominal pain, or vomiting, with nausea being the most common of these side effects. Remember, one of the ways GLP-1s work is by slowing down digestion and increasing the feeling of fullness between meals — hence why the most common side effects all involve the gastrointestinal system. These side effects usually occur within the first 8-20 weeks of starting the medication, and they can be dependent on dosage. The good news is that once a stable, maintainable dose is achieved, the side effects should subside. Sometimes, the side effects come back on the day of injection or within the day after, but this can vary from patient to patient.
Less commonly, some patients on GLP-1s will report fatigue, hair loss, belching or burping, heartburn or reflux, and dizziness. More severe side effects, like hypoglycemia (low blood sugar), pancreatitis, gastroparesis, aspiration during surgery, and other more serious complications have been reported, but this is in a low percentage of the population.
As nutritionists and dietitians, we cannot prescribe GLP-1 medications. If you have concerns regarding side effects, it’s worth reaching out to your physician. One of the things we can do, however, is help the patient devise a strategy to manage these side effects. For example, if a patient frequently experiences nausea on the day of their injection, we may want to consider low-fiber, bland foods for that day instead of flavorful, denser options.

What to prioritize for optimal health:

Rapid weight loss — regardless of GLP-1 use or not — predisposes the body to losing muscle mass, bone density, and nutrient deficiencies. The weight changes and side effects listed above will pose unique nutritional challenges for both the patient and their dietitian or nutritionist. Everyone’s experience with GLP-1s will be different. As providers, our goal is to mitigate side effects, prevent detrimental changes in body composition, and create meaningful, lasting behavior change so that a patient is successful in their GLP-1 journey. While the GLP-1 medication will result in weight loss, a nutrient-dense diet and thoughtful exercise program should be implemented no matter what.

Some initial recommendations to support metabolic health, sustainable weight change, and prevent deficiencies are…

• Aim for at least 3 eating opportunities per day — either through meals or meal(s) plus snack(s), depending on what’s tolerated.
• Build each meal or snack around protein, then add in the high-fiber produce and starchier carbs as the patient is able to.
• Create a list of easy, accessible, and palatable foods to keep on hand if experiencing nausea or other side effects.
• Going off of the point above, fiber intake is extremely important — low dietary fiber intake, regardless of the reason, can negatively impact gastrointestinal health and the gut microbiome. Fiber intake may need to be personalized to the individual on GLP-1s based on their side effects and experience. A nutritionist or dietitian can help find a strategy that is unique to the patient.
• Take a multivitamin to ensure all daily recommended micronutrient targets are met — speak to a dietitian or nutritionist for suggestions on brands and dosages!
• Strength train at least 2-3 times per week to maintain or increase lean muscle mass. This can be done at home, in a gym, or through group fitness classes.
• Build routines to create sustainable habits for long-term health — everyone’s life will look different, and one of our roles as nutrition providers is to help our patients change their behaviors in a way that works for them.

In summary:

It’s important to remember that GLP-1s are not going to be an immediate fix for metabolic health and weight concerns; anyone taking a GLP-1 still needs to place a high priority on protein intake, nutrient-dense and high-fiber foods, and exercise to optimize body composition. However, with the right care team and tools, lasting and sustainable change is possible.