Pharmacists Are Crucial Partners in Guiding Nutrition and Supplement Use With GLP-1s

As glucagon-like peptide-1 (GLP-1) medications become a cornerstone of diabetes treatment and weight management, new challenges around adequate nutrition have emerged for patients and health care providers. Although these medications effectively improve insulin utilization and promote weight loss by slowing gastric motility and reducing calorie intake, these specific benefits can lead to an abundance of nutritional issues, including dehydration, muscle loss, and vitamin and mineral deficiencies.

Many patients wish to stay on GLP-1s because of their benefits and often seek out ways to address adverse effects. As the first point of care for many patients, pharmacists play a crucial role in addressing these nutrition concerns and highlighting how comprehensive supplementation can provide relief to impacted patients.

“Patients are looking for something [to help], and when they’re on these GLP-1s, they’re excited to be on it. And when they start losing the weight, they’re really excited. But then they do get these [adverse] effects, so they’re looking for something to counteract the [adverse] effects,” board-certified gastroenterologist Rajesh Dhirmalani, MD, said in an interview with Pharmacy Times.

UNDERSTANDING THE ROLE OF GLP-1s

GLP-1 is a hormone produced in the small intestine that plays various roles in managing blood glucose and appetite by triggering the pancreas to release insulin, which lowers blood glucose. It also blocks glucagon secretion, preventing blood glucose levels from rising. GLP-1 also slows stomach emptying, leading to a steadier release of glucose into the bloodstream, and increases the feeling of fullness after eating by affecting the brain’s hunger and satiety centers.¹

GLP-1 agonists are most commonly injectable medications that are administered in the stomach, outer thighs, upper buttocks, and the back of the arm, although oral GLP-1s are becoming increasingly available. The medications aim to manage glucose levels among individuals with type 2 diabetes and help treat overweight and obesity. Frequently prescribed GLP-1s include dulaglutide (Trulicity; Eli Lilly and Company), liraglutide (Victoza; Novo Nordisk), semaglutide injection (Ozempic, Wegovy; Novo Nordisk), semaglutide tablets (Rybelsus; Novo Nordisk), and tirzepatide (Mounjaro; Eli Lilly and Company), which is a dual GLP-1 and glucose-dependent insulinotropic polypeptide receptor agonist.¹

“GLP-1s slow motility, so people are feeling full easier. And if they’re feeling full, then they’re not eating as much. They’re decreasing their caloric intake. That’s really the mechanism of how people are losing weight,” Dhirmalani said.

NUTRITIONAL DEFICIENCIES ASSOCIATED WITH GLP-1 TREATMENT

Adverse effects from GLP-1 medications are common, especially when first starting treatment. However, they are typically mild and decrease over time as the body adjusts to a stable dose. The reduction in appetite and caloric intake can lead to insufficient consumption of necessary vitamins and minerals, raising concerns for individuals with a low daily calorie intake. Nutritional deficiencies often result in physical symptoms such as fatigue, hair loss, skin issues, muscle weakness, and poor wound healing.²

“Usually the big [deficiencies are] vitamin D, vitamin B12, folic acid, [and] iron…because you’re having slower motility [and] slower absorption, so eventually, people start to lose the ability to absorb these and then you get this deficiency,” Dhirmalani said. “With the vitamins and the B12 and the vitamin Ds, you can have risks of bone loss, [a] decrease in iron, and become a little bit anemic.”

Data from previous clinical trials published in the American Journal of Clinical Nutrition demonstrated that muscle loss was linked to nearly 20% of total weight reduction. However, this varies based on sex, degree of calorie restriction, speed of weight loss, and whether a patient does strength training.²

The rapid weight loss associated with GLP-1 treatment can also impact an individual’s bone density, causing older adults and women to be more susceptible to bone loss. These findings highlight the importance of proper nutrition and exercise when being treated with GLP-1s.²

“Later on, as [patients are] on [GLP-1s] for 6 months to a year, you’re losing weight, but you’re also losing muscle mass. You start to see some muscle wasting with that,” Dhirmalani said.

NUTRITIONAL PRIORITIES TO SUPPORT GLP-1 THERAPY

Health care providers can help mitigate the risk of nutrient deficiencies in patients on GLP-1s. Dhirmalani emphasized that pharmacists should recommend appropriate supplements and encourage patients to maintain adequate vitamin intake. Because constipation is more common with GLP-1s, fiber, prebiotics, probiotics, and strategies to support gut health and microbiome balance are important as calorie intake decreases.

Equally essential is maintaining proper fluid intake, considering amino acid or protein supplements to reduce muscle wasting, and prompting regular exercise—particularly strength training—to help preserve and build muscle.

Clinicians should encourage a varied diet of minimally processed foods, such as fruits, vegetables, whole grains, and lean proteins, while avoiding refined carbohydrates, sugary drinks, and processed foods. Additionally, dietary supplements such as vitamin D and B12 or a multivitamin should be considered to address potential nutrient deficiencies.²

Dhirmalani acknowledged that many patients struggle to keep up with multiple individual supplements. All-in-one options such as Replenza—a nutritional supplement system designed specifically for GLP-1 medication users—make it easier for patients to stay consistent with their medications. These supplements are often offered as a powder or tablet and combine fiber, prebiotics, probiotics, vitamins, amino acids, and collagen to help address constipation, nutritional deficiencies, and muscle mass concerns.

“[Patients are] finding that it’s difficult to supplement for all the different things, so they’re finding…an all-in-one type of product, which is easy, because the last thing they want to do is try to supplement with all these things,” Dhirmalani said.

By guiding patients toward comprehensive options, pharmacists can simplify supplement use, improve adherence, and support patients in staying on therapy. Dhirmalani emphasized that recommendations should be tailored because not every patient will need the same supplementation. Pharmacists should carefully evaluate individual needs, comorbidities, and current medications before suggesting a product.

REFERENCES

1. GLP-1 agonists. Cleveland Clinic. Updated July 3, 2023. Accessed September 18, 2025. https://my.clevelandclinic.org/health/treatments/13901-glp-1-agonists

2. Mozaffarian D, Agarwal M, Alexander L, et al. 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 (Silver Spring).2025;33(8):1475-1503. doi:10.1002/oby.24336