A 42-year-old schoolteacher began GLP-1 therapy for obesity and Type 2 diabetes. Within months, her appetite dropped sharply. She skipped meals and ate very small portions. Although her weight and glucose levels improved, she developed fatigue and hair fall. Tests showed low vitamin B12, vitamin D and iron. Her largely vegetarian, carb-heavy diet had shrunk further with treatment. With nutrition counselling, protein-rich small meals, leafy vegetables, dairy and targeted supplements, her deficiencies improved while she continued therapy safely.
GLP-1-based therapies such as semaglutide and tirzepatide are increasingly being used in India for managing Type 2 diabetes and obesity. These medications work by slowing gastric emptying, improving insulin response, and most notably, reducing appetite. While this helps in weight loss and glycaemic control, it also raises an important but often overlooked concern: whether patients are getting adequate micronutrients when their overall food intake drops.
A reduced appetite is one of the most common effects of GLP-1 therapies. Recipients often report eating smaller portions, skipping meals, or feeling full quickly. In the Indian context, this can be particularly relevant because diets are already deficient in proteins and macronutrients. Many individuals rely heavily on carbohydrate-rich staples like rice, wheat and potatoes, with inconsistent intake of protein, fruits and vegetables. When appetite declines further, the risk of micronutrient gaps increases.
What are common deficiencies?
Common deficiencies that may arise include iron, vitamin B12, vitamin D, calcium and folate. For example, vitamin B12 deficiency is already prevalent in India, especially among those following predominantly vegetarian diets. When food intake reduces, intake of vitamin B12-rich foods such as dairy and animal proteins may fall further. In addition, many individuals receiving GLP-1 therapy are co-prescribed metformin for diabetes, which may further increase the risk of vitamin B12 deficiency. Similarly, iron deficiency, particularly among women, can worsen if meals become irregular or less diverse.
GLP-1 therapy has also been associated with increased rates of vitamin D deficiency. Many people with obesity already have low vitamin D levels due to sequestration of fat-soluble vitamins within adipose tissue, reducing their availability in circulation. Rapid weight loss and reduced food intake during treatment may further limit vitamin intake. Fat-soluble vitamins such as vitamins A, D, E, and K depend on adequate dietary fat and absorption, and their balance can be affected because many develop aversion to fat while on GLP-1 therapy. While these changes are not directly caused by the drug, they highlight the need to monitor and address micronutrient status during treatment.
Watch out for protein
Another concern is protein intake, which, while not a micronutrient, plays a critical role in preserving muscle mass during weight loss. Many individuals on GLP-1 therapies tend to prioritise light, easy-to-eat foods, which may not always be protein-rich. This can indirectly affect micronutrient status as well, since nutrient-dense foods are often replaced with low-nutrient options.
How to get your nutrients
Given these patterns, proactive nutritional guidance becomes essential. Individuals on GLP-1 therapy should be encouraged to focus on nutrient density rather than quantity. Small, frequent meals that include a balance of protein, healthy fats and micronutrient-rich foods can help. For instance, incorporating curd, paneer, lentils, green leafy vegetables, nuts and seasonal fruits can improve nutrient intake even in smaller portions.
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Supplementation may also be considered in some cases, especially for vitamin B12 and vitamin D, where deficiencies are widespread. However, this should be guided by a healthcare professional based on individual assessment. Monitoring of key parameters such as haemoglobin, and if necessary, vitamin B12 and vitamin D levels, can help identify gaps early.
It is equally important for clinicians to counsel recipients before initiating GLP-1 therapy. Setting the expectation that appetite will reduce, and that mindful eating will be necessary, can make a significant difference. Instead of focusing only on weight loss, discussions should also include maintaining nutritional adequacy.
While GLP-1 therapies offer significant benefits in managing diabetes and obesity, they also bring a shift in eating behaviour that can impact micronutrient intake. In the Indian setting, where baseline nutritional imbalances are common, this requires careful attention. With the right dietary strategies and monitoring, individuals on GLP-1 therapy can achieve the benefits without compromising on essential nutrition.
(Dr Saptarshi Bhattacharya is senior consultant, endocrinology, Indraprastha Apollo Hospital, New Delhi)
