People prescribed the new generation of weight loss drugs may not receive sufficient nutritional guidance to support safe and sustainable weight loss, leaving them vulnerable to nutritional deficiencies and muscle loss, say experts at UCL and the University of Cambridge in a new paper.
The team say nutritional guidance should always be given alongside treatment, and that further research is needed into what this nutritional guidance should be, as there are currently gaps in the evidence.
Weight loss drugs such as semaglutide and tirzepatide – available under brand names including Ozempic, Wegovy and Mounjaro – suppress appetite, increase a feeling of being full, and reduce food cravings.
These drugs can reduce calorie intake by between 16-39%, making them a powerful tool to help people living with obesity and overweight. However, there has been little research to examine their impact on diet quality, adequacy of micronutrients (vitamins and minerals), or protein intake. Adequate protein is important for maintenance of muscle.
This lack of research means it may be difficult for patients to receive the nutritional advice they need while taking a weight-loss medication, said the team behind the BRC-supported research which is published in Obesity Reviews.
Dr Adrian Brown, an NIHR Advanced Fellow from the Centre of Obesity Research at UCL, who is supported by the BRC and who is the study’s corresponding author, said: “Obesity management medications work by suppressing appetite, increasing feelings of fullness, and altering eating behaviours, which often leads people to eat significantly less. This can be highly beneficial for individuals living with obesity, as it supports substantial weight loss and improves health outcomes.
“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, fibre, vitamins, and minerals essential for maintaining overall health.”
Dr Marie Spreckley, from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge, who led the research team, said: “If nutritional care is not integrated alongside treatment, there’s a risk of replacing one set of health problems with another, through preventable nutritional deficiencies and largely avoidable loss of muscle mass. This represents a missed opportunity to support long-term health alongside weight loss.”
Inadequate micronutrient intake can put people at risk of a range of conditions, from fatigue and an impaired immune response to hair loss and osteoporosis. Loss of lean mass – in most cases, muscle – increases the risk of weakness, injury and falls.
The researchers identified just 12 studies that looked at nutrition and diet alongside treatment with semaglutide or tirzepatide. Even then, as the trials varied widely in their approaches to dietary advice and nutritional assessment and lacked standardised protocols and reporting, it was difficult to reach robust conclusions to inform the optimal support for people taking weight loss drugs.
Given the widespread – and increasing – use of these medications and the urgency of providing advice to individuals using the drugs, as well as calling for more research the researchers argue that we can turn to what has been learnt from the guidance and support offered alongside weight loss surgery, such as gastric bands. These principles include prioritising nutrient-dense foods including high-quality protein intake.
The research was funded by the National Institute for Health and Care Research (NIHR), with additional support from the Medical Research Council.
