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P. Morgan Global Research estimates that 10 million Americans were being treated with glucagon-like peptide-1 (GLP-1) weight-loss drugs in 2025 and forecasts that the number of patients will increase to 25 million by 2030. These drugs suppress appetite and increase feelings of fullness, resulting in a reduced calorie intake of 16 to 39 percent. However, research suggests that up to 40 percent of weight loss may come from lean body mass, including muscle.

A systematic review of 12 studies in Obesity Reviews points out the lack of dietary advice and support for GLP-1 patients. As they eat less, these patients may not get enough protein, fiber, vitamins and minerals, potentially leading to muscle loss, fatigue, impaired immune response, hair loss and osteoporosis. Muscle loss increases the risk of injuries and falls.

The review’s authors advise GLP-1 patients to consult a dietitian at the start of treatment and focus on nutrient-dense, high-quality foods to maintain lean muscle mass while avoiding saturated and other fats. They also suggest that small, frequent meals may alleviate side effects like nausea. The authors emphasize the need for further research to determine the necessary information and support for patients, as well as how the drugs affect eating habits, appetite, well-being and quality of life, to establish dietary care best practices alongside weight-loss drugs.