Robbie Williams got scurvy. He said so himself in 2025, after taking "something like Ozempic" and stopping eating. The headlines ran. The pirate jokes came. And then the coverage, almost universally, missed the point by a wide margin.
Scurvy is not the story. The story is that we are prescribing appetite-suppressing medications to millions of people and sending them home with essentially no nutritional guidance. That is the scandal. The vitamin C deficiency is just the symptom of a much larger failure.
What the Research Actually Shows
GLP-1 drugs can reduce calorie intake by 16 to 39 percent, making them genuinely powerful tools for weight loss. That is not in dispute. The drugs work. 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. A separate figure is even more jarring: 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. That is a near-fivefold difference. That is not a rounding error.
Vitamin C gets the headlines because scurvy is theatrical. Bleeding gums, loosened teeth, wounds that will not close. GLP-1 users report low appetite and early satiety, so fruits and vegetables that contain vitamin C are not consumed as often, but are instead replaced with toast, crackers, and processed food to accommodate gastrointestinal issues like nausea. The mechanism is not mysterious. Some people end up eating 600 to 1000 calories per day without realizing it, and thereby undereating vital nutrients and vitamins. When your diet is already nutrient-poor and you then suppress appetite by a third or more, you have mathematically guaranteed a deficiency. Which deficiency depends on which nutrients were marginal to begin with.
And scurvy is not even the worst-case scenario. Iron deficiency can cause anemia, while vitamin B1 deficiency leads to beriberi and Wernicke's encephalopathy, a potentially life-threatening brain disorder. Wernicke's encephalopathy from a weight-loss drug. That sentence should make prescribers uncomfortable. Another challenge is that symptoms of nutrient deficiency, including fatigue, nausea, and irritability, can overlap with the common side effects of GLP-1 medications, making problems harder to spot early. So clinicians are doubly flying blind: no dietary monitoring, and symptoms that mimic the drug's ordinary profile.
The Evidence Gap Nobody Wants to Talk About
Here is what should genuinely anger you. Research published in Obesity Reviews by a team led by Dr. Marie Spreckley at the University of Cambridge found a lack of robust evidence surrounding nutritional advice and support, with very little research examining the impact of GLP-1 drugs on diet quality, protein intake, or adequacy of micronutrients. These are the trials that generated the approval data. The trials that convinced regulators and physicians to prescribe these drugs to millions of people. And they did not track what the patients were eating.
A scoping review of 129 randomized trials of liraglutide, semaglutide, and tirzepatide found minimal detailed reporting on nutritional behavior components, diet quality, or food intake. One hundred and twenty-nine trials. The field of GLP-1 research is not small. This was not an oversight in one underpowered pilot study; this is a systematic blind spot in the entire evidence base.
The comparison that puts this in sharpest relief: bariatric surgery. Structured nutritional follow-up, including regular dietary reviews and biochemical monitoring, is a hallmark of post-bariatric care. In contrast, GLP-1 receptor agonists are typically administered with minimal ongoing nutritional oversight. Bariatric surgery and GLP-1 drugs produce meaningfully similar physiological outcomes: dramatic caloric restriction, significant weight loss, and real risk of lean mass reduction. One comes with a mandatory dietitian referral and regular bloodwork. The other comes with a prescription and a pamphlet, if you are lucky. Use of GLP-1 receptor agonist therapies has increased rapidly in a very short period, but the nutritional support available to people using these medications has not kept pace. Many people receive little or no structured guidance on diet quality, protein intake, or micronutrient adequacy while experiencing marked appetite suppression.
There is also a subtler problem that the pirate-disease coverage ignored entirely. An opinion published in the BMJ in July 2025 noted that although obesity is often thought of as a case of being "over-nourished," the opposite is frequently true, with muscle wasting and nutrient deficiencies being just as common in people with obesity as in those who are underweight. GLP-1 users are not starting from a position of nutritional abundance. They are frequently already depleted. Then we suppress their appetite by up to 39 percent and wonder why they get sick.
The Fix Is Not a Supplement Stack
The good news, to the extent there is any: scurvy is reversible with a multivitamin or a 100 to 200 milligram vitamin C supplement. The intervention costs less than a dollar a day. The bad news is that recommending a supplement after the fact is not a nutrition strategy; it is damage control. And vitamin C is only one of the deficiencies that matter.
Evidence suggests that lean body mass, including muscle, can constitute up to 40 percent of total weight lost during GLP-1 treatment. You are not just losing fat. You may be losing significant muscle, bone mineral density, and micronutrient reserves simultaneously, while feeling full and virtuous. The scale is going down. Everything else may be going with it.
What needs to happen is straightforward, which is precisely why it is being ignored. According to Clare Collins, laureate professor of nutrition and dietetics at the University of Newcastle, future clinical trials on GLP-1s should include validated dietary assessment tools and transparent reporting of food and nutrient intakes. That is the research side. On the clinical side: if you are on these medications, you should be seeing your doctor at least once a year and getting labs drawn to check your vitamin and mineral levels, not just your weight. Bloodwork. A dietitian referral. Monitoring that matches the physiological impact of the intervention.
GLP-1 drugs work. I am not arguing otherwise. The weight loss is real, the cardiovascular data are promising, and for patients with serious obesity-related disease, the benefit-to-risk calculation is favorable. But if nutritional care is not integrated alongside treatment, there is a risk of replacing one set of health problems with another, through preventable nutritional deficiencies and largely avoidable loss of muscle mass.
Robbie Williams's gums bled. That is not a drug side effect. That is what happens when a powerful appetite suppressant is handed out without a nutrition plan attached. The scurvy is the headline. The missing dietitian referral is the story.
