Experts warn of malnutrition risks on GLP-1s

Collins’ systematic review assessed the diets of about 50,000 adults on GLP-1s. Extreme cases of malnutrition carry the risk of brain damage, heart problems and death. Common side effects of the drugs, fatigue, nausea, diarrhoea and constipation, overlap with symptoms of nutrient deficiencies and can be easily missed, Collins said.

Collins said GLP-1s, including Trulicity, Wegovy and Mounjaro, had powerful positive health effects, including significant weight loss and improved blood glucose control. She said there was an urgent need to address the lack of research into malnutrition risk.

One patient, a Bendigo mother who asked that her surname be withheld, said she struggled to pick up her three-year-old daughter after losing significant weight in a month on a GLP-1 prescribed via telehealth. “I was feeling really weak and shaky … I wasn’t eating enough to keep myself going,” she said. She added more protein and started strength training, which she said has “definitely made a difference”.

Collins said that when people significantly cut down their food intake, they risk not getting enough protein to protect muscles, as well as vitamins and minerals needed for healing, hair growth and energy production. If left untreated, a thiamine (B1) deficiency can develop into Wernicke’s encephalopathy, a rare neurological disorder that can cause irreversible brain damage, with some cases identified in people who rapidly lost weight on GLP-1s. Magnesium deficiency can lead to cardiac arrest in severe cases.

Dietitian and University of Sydney Clinical Associate Professor Janet Franklin said there was limited scientific evidence linking GLP-1s with malnutrition. “I think it’s a theoretical risk [but it’s] one that you need to be conscious of,” she said. She questioned whether the risk was not being seen because people were eating enough or because testing was not being done.

Dr Karen Spielman, chair of the RACGP’s Specific Interests Psychological Medicine group, said primary health providers needed more support to prevent inappropriate prescribing as GLP-1s become more widespread. “Rapid weight loss at any body-size or shape can be really scary and can precipitate medical conditions,” she said. “You’ve got to assess and monitor carefully … this is a really important opportunity for us not to cause harm.” Spielman advocated for clinical guidelines and higher rebates for longer consultations.

Some food chains have adapted for the Ozempic wave. Guzman y Gomez expanded its mini range, and meal kit service Marley Spoon launched a “GLP-1 Support range” with smaller servings and higher protein and fibre. Support is available from the Butterfly National Helpline on 1800 33 4673.