GLP-1 weight loss medications such as semaglutide and tirzepatide have changed the conversation around obesity treatment. Sold under brand names like Ozempic, Wegovy and Mounjaro, these medications are helping many people lose significant amounts of weight by reducing appetite and increasing feelings of fullness.
But while the focus has largely been on how much weight people are losing, far less attention has been given to what might be lost nutritionally along the way.
Recent research from experts at the University of Cambridge and UCL raises an important question: are people using these medications getting enough nutritional guidance to protect their long-term health?
How GLP-1 Weight Loss Drugs Affect Eating
GLP-1 receptor agonists mimic a hormone released after eating. This hormone signals fullness, slows digestion, and reduces appetite. As a result, many users naturally eat much less than before. Studies suggest calorie intake can fall by as much as 16 to 39 percent.
For people living with obesity, this can be life-changing. Lower calorie intake often leads to meaningful weight loss and improvements in blood sugar, blood pressure and overall metabolic health. However, eating less does not automatically mean eating well. When appetite drops sharply, total food intake falls. Without careful planning, that can mean less protein, fewer vitamins and minerals, and reduced overall diet quality.
Muscle Loss and Nutrient Deficiencies: A Hidden Concern
One of the less discussed findings in the research is that lean body mass, including muscle, may account for up to 40 percent of total weight lost during treatment.
Reductions in lean mass can have consequences over time, influencing strength, balance and metabolic health. Preserving muscle during weight loss is especially important for older adults, where reduced lean mass increases the risk of weakness and falls. At the same time, lower overall food intake can increase the risk of inadequate protein, fibre, vitamins and minerals. Over time, insufficient intake may contribute to fatigue, hair thinning, weakened immune function or reduced bone health. The concern raised by researchers is not that these medications are unsafe, but that nutritional support has not kept pace with their rapid uptake.
NHS Guidance Versus Private Use
In the UK, NICE recommends semaglutide for weight management only under specific conditions and as part of a structured programme that includes dietary changes and increased physical activity. In practice, however, most users obtain GLP-1 medications privately. Estimates suggest that around 1.5 million people in the UK are currently using these drugs, and the majority are not doing so through NHS programmes. In private settings, structured follow-up and nutritional guidance are not always part of the process. As a result, some people may not receive the same level of dietary support.
Current Evidence on Diet and GLP-1 Use
The research team reviewed available studies examining diet and nutrition alongside semaglutide or tirzepatide use. Only 12 studies met the criteria, and they varied widely in how they measured diet, protein intake and nutritional outcomes.
This makes it difficult to draw firm conclusions about the best nutritional strategy for people using these medications. What is clear, however, is that appetite suppression alone is not a nutrition plan.
The Bigger Picture: Weight Loss Is Not the Only Goal
GLP-1 medications are transforming obesity care. For many people, they offer a treatment option that was not previously available. At the same time, weight loss should not come at the expense of muscle mass, nutritional adequacy or long-term health.
Reduced appetite changes eating behaviour dramatically. Without structure, it can lead to unintentional under-nutrition. With the right guidance, it can support sustainable fat loss while preserving strength and overall wellbeing. The current gap is not in the medication itself, but in the support surrounding it.
If you are taking Ozempic, Wegovy or similar treatments, it may be worth asking:
- Am I consuming enough protein each day?
- Is my diet still varied and nutrient-dense?
- Should I consider monitoring key vitamins and minerals?
- Am I maintaining muscle through resistance exercise?
Small adjustments can make a significant difference over time. Weight loss medications are a tool. Nutrition remains the foundation.
Supporting Nutrition During GLP-1 Treatment
GLP-1 medications reduce appetite quickly, and for many people, these changes in eating habits are more than expected. When food intake drops, nutrient intake can drop with it. Paying attention to protein, overall diet quality and key micronutrients becomes increasingly important during weight loss. In some cases, individuals may consider using a well-formulated food supplement to help maintain nutritional balance while calorie intake is reduced. If needed, a simple multivitamin or targeted nutrient supplement can help support overall intake while appetite is reduced. Products such as those offered by Sona are intended to complement the diet rather than replace it. The aim is to maintain nutritional balance during weight loss, not to substitute whole foods. Long-term health, however, still depends on adequate nutrition, muscle preservation and consistent daily habits.
References;
University of Cambridge. "The overlooked nutrition risk of Ozempic and Wegovy." ScienceDaily. 4 February 2026.