Dieticians are warning that GLP-1 use can lead to extreme malnutrition, manifesting in diseases like scurvy, amid findings that the vast majority of studies fail to consider patients’ eating habits.
While GLP-1s like Ozempic and Wegovy have surged in popularity in recent years—and are now available through injections and in pill form—leading dieticians in Australia have discovered that existing research hasn’t considered what patients are eating, and how much.
Nutritional Deficiencies
While the drugs work by suppressing appetite, eating too little or making poor dietary choices can lead to further issues.
“A reduction in body weight does not automatically mean the person is well-nourished or healthy,” Professor Clare Collins told the Australian Financial Review (AFR). “Nutrition plays a critical role in health, and right now it’s largely missing from the evidence.”
She added that only two trials had recorded or published what GLP-1 users were eating. The current data shows that many patients using weight-loss medication are functionally malnourished, which can lead to severe vitamin deficiencies.
A 2025 study of adults with type 2 diabetes found that more than 20 percent of participants had nutritional deficiencies after 12 months of GLP-1 use. And a study examining patients before joint surgery found that 38 percent of GLP-1 users suffered from malnutrition, versus 8 percent for patients not using GLP-1s.
Last year, British pop artist Robbie Williams told The Mirror he had developed a “17th century pirate disease” after “taking something like Ozempic.” He was referring to scurvy, a rare but serious vitamin C deficiency. In the worst cases, the illness can lead to death.
“I’d stopped eating, and I wasn’t getting nutrients,” he said.
It’s exactly the kind of health emergency the dieticians are working to combat.
The Proposed Solution
“Let’s not wait for every GP (general practitioner) to see a case of scurvy, let’s get on the front foot and link these GP chronic management plans to a dietician referral,” said Collins. GLP-1 use has also been tied to thiamine deficiency, which can cause neurological and cardiovascular disease.
Magriet Raxworthy, CEO at Dieticians Australia, said it’s essential that GLP-1 users receive nutritional guidance while taking the drug.
“Without personalized medical nutrition therapy provided by a dietitian, people may struggle to meet their nutritional needs and can be placed at risk of significant muscle loss, bone density loss, micronutrient deficiencies, and disordered eating behaviors,” she said, according to the AFR. “In this case, it’s clear—medication alone does not deliver sustainable health outcomes.”
Some GLP-1 providers do offer nutrition assistance, but the issue hasn’t yet been centralized in a way that effectively prevents serious deficiencies that can accompany the medication.
—Ava Levinson
This article originally appeared on Fast Company’s sister website, Inc.com.
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