The Overlooked Nutritional Risks of New Weight Loss Medications
Popular weight-loss drugs like Ozempic, Wegovy, and Mounjaro are proving highly effective for individuals with obesity and overweight, but experts are raising concerns about a potential hidden cost: nutritional deficiencies. A growing body of research suggests that many patients prescribed these medications aren’t receiving adequate guidance on maintaining a healthy diet, potentially leading to muscle loss and a lack of essential vitamins and minerals.
The medications work by mimicking the effects of glucagon-like peptide-1 (GLP-1), a hormone naturally released after eating. This results in reduced appetite, increased feelings of fullness, and decreased food cravings. Calorie intake can drop significantly – between 16% and 39% – contributing to substantial weight loss. However, this dramatic reduction in food consumption, without careful nutritional planning, can create imbalances.
Limited Nutritional Support
Research published in Obesity Reviews, led by Dr. Marie Spreckley of the University of Cambridge, revealed a striking lack of high-quality evidence on how nutritional advice impacts patients using these medications. The study found limited data on the effects of these drugs on calorie intake, body composition, protein intake, and overall patient experiences. This gap in knowledge is prompting calls for more comprehensive support for individuals undergoing treatment.
Dr. Adrian Brown, an NIHR Advanced Fellow at UCL’s Centre of Obesity Research, explains that while appetite suppression is beneficial for weight loss, it also carries risks. “Obesity management medications work by suppressing appetite…which can be highly beneficial. However, without appropriate nutritional guidance and support from healthcare professionals, there is a real risk that reduced food intake could compromise dietary quality, meaning people may not get enough protein, fiber, vitamins, and minerals essential for maintaining overall health.”
Access and Guidance Disparities
Current guidelines from the National Institute for Health and Care Excellence (NICE) recommend semaglutide for weight management only for individuals with a body mass index (BMI) of at least 35.0 kg/m2 and coexisting health conditions, such as type 2 diabetes or cardiovascular disease. When prescribed within the National Health Service (NHS), the drug is intended to be part of a broader program including a reduced-calorie diet and increased physical activity.
However, the majority of patients are accessing these medications outside of the NHS. Approximately 1.5 million people in the UK are currently using GLP-1 drugs, with an estimated 95% obtaining them privately. In these private settings, consistent and comprehensive nutritional advice and follow-up support are not always provided.
Dr. Spreckley emphasizes the urgency of addressing this disparity. “Use of GLP-1 receptor agonist therapies has increased rapidly in a very short period of time, but the nutritional support available to people using these medications has not kept pace. Many people receive little or no structured guidance on diet quality, protein intake, or micronutrient adequacy while experiencing marked appetite suppression.”
Potential Health Consequences
The consequences of inadequate nutritional support can be significant. Researchers warn of potential vitamin and mineral deficiencies, which can lead to fatigue, weakened immune function, hair loss, and osteoporosis. Perhaps more concerning is the potential for substantial loss of lean muscle mass, accounting for as much as 40% of total weight lost during treatment. This muscle loss can increase the risk of weakness, injuries, and falls.
Clare Collins, a professor in nutrition and dietetics at the Newcastle School of Health Sciences, has warned that the widespread use of these drugs could even lead to malnutrition and, in extreme cases, scurvy, highlighting the critical need for dietary awareness.
Drawing Lessons from Bariatric Surgery
Given the limited research specifically addressing nutritional needs during GLP-1 therapy, researchers suggest drawing lessons from the established protocols used after bariatric surgery, such as gastric band procedures. These procedures also lead to significant reductions in appetite and food intake, and well-defined nutritional guidelines are in place to mitigate potential deficiencies.
Dr. Cara Ruggiero, a co-author from the MRC Epidemiology Unit at the University of Cambridge, suggests prioritizing nutrient-dense foods, particularly high-quality protein distributed evenly throughout meals, to help preserve lean mass during periods of reduced appetite and rapid weight loss. The available evidence does not support strict low-fat diets, but personalized guidance on fat intake, aligning with national dietary recommendations, may be beneficial.
Ongoing Research and Patient Perspectives
Recognizing the need for more comprehensive understanding, the research team has launched AMPLIFY, a project aimed at exploring the lived experiences of individuals using GLP-1 medications. This initiative will focus on understanding how these drugs impact daily life, including appetite, eating patterns, well-being, and quality of life, with a particular emphasis on gathering perspectives from historically under-represented communities.
“These medications are transforming obesity care, but we know very little about how they shape people’s daily lives,” Dr. Spreckley stated. “That’s what we’ll explore…to help shape the future of obesity treatment.”
The research was funded by the National Institute for Health and Care Research (NIHR), with additional support from the Medical Research Council and the NIHR UCLH Biomedical Research Centre.
