Australian researchers warn that popular GLP-1 weight-loss drugs may be exposing users to malnutrition and even rare conditions like scurvy, because trials and prescribing practices often overlook what people actually eat while losing weight.
Scurvy is a disease tied to severe vitamin C deficiency, historically linked to sailors on long voyages who lacked fresh fruit and vegetables. Its symptoms are striking and varied: anemia, loose or lost teeth, bleeding under the skin, bruising, swollen legs, rough scaly skin, dry brittle hair that coils, nonhealing wounds, and swollen, bleeding gums. These signs can appear surprisingly quickly when vitamin C intake drops sharply. That makes the condition relevant again as people adopt aggressive appetite-suppressing medications.
A systematic review from the Hunter Medical Research Institute points to a clear blind spot: major diabetes and obesity drug trials report weight loss but rarely record what participants are eating. Without that information, doctors and patients can miss whether pounds come off with balanced nutrition or with dangerous gaps in vitamins and minerals. This absence of dietary reporting leaves clinicians guessing about the true health impact of these drugs beyond the number on the scale.
“A reduction in body weight does not automatically mean the person is well-nourished or healthy,” Clare Collins, laureate professor of nutrition and dietetics at The University of Newcastle, wrote in a press release statement. Those exact words cut to the core problem—losing weight is not the same as improving nutritional status. When diet quality falls, so do essential nutrients that the body needs to function and heal.
Collins also raised “major concerns about the risk of malnutrition, including macro and micro-nutrient deficiencies, with adverse metabolic and nutritional effects being reported,” adding that the appetite-suppressing action of GLP-1 and GIP drugs is a double-edged sword. “While this mechanism drives weight loss, it also increases the risk of inadequate protein, fiber, vitamin and mineral intakes if diet quality and nutritional adequacy are not carefully monitored,” she cautioned. Those gaps can show up as fatigue, irritability, or symptoms easily mistaken for side effects of the drugs themselves.
The report notes that nutrient shortfalls are not limited to vitamin C. “There are other nutrients that, if not consumed in adequate amounts, can lead to deficiencies,” Collins said. For instance, iron deficiency commonly leads to anemia, while a lack of vitamin B1 can cause beriberi or, in severe cases, Wernicke’s encephalopathy. These are avoidable conditions if diet quality is maintained during medical weight-loss efforts.
High-profile cases have drawn public attention to the issue. British pop singer Robbie Williams was diagnosed with scurvy in 2025, previously sharing that he experienced symptoms of the “17th-century pirate disease” after he’d been taking “something like Ozempic.” Anecdotes like that underline how quickly nutrient problems can surface when appetite and intake change dramatically.
For people losing weight rapidly on these medications, the researchers stress the need for intentional nutrition planning rather than hoping medical guidance alone will cover it. “It is challenging to assess whether your nutrient intake is adequate by yourself,” she said. “People may also require a specific multivitamin or mineral supplement, along with medical nutrition therapy support.”
Looking ahead, the review calls for better research standards so clinicians can make informed choices. Future clinical trials should include “validated dietary assessment tools” and “transparent reporting of food and nutrient intakes,” Collins suggested. “This will help improve the nutrition-related health and wellbeing outcomes for individuals prescribed these medications, while supporting adherence and long-term health,” she said.
Policy and prescribing practice should adapt quickly to these findings so weight-loss strategies protect overall health, not just reduce pounds. “We’re calling for greater attention to nutrition when these medications are being prescribed in order to avoid malnutrition risk.”
