GLP-1 medications are highly effective at reducing calorie intake — sometimes by 30–50%. While that's excellent for weight loss, it also means your body is getting significantly fewer vitamins and minerals than before. Over months of treatment, subtle deficiencies can accumulate, leading to hair loss, fatigue, bone density loss, and immune suppression.
A comprehensive multivitamin covering 100% of RDA for B vitamins, vitamin C, zinc, and selenium provides a safety net when dietary variety is reduced. It won't cover everything, but it fills the most common gaps efficiently.
Vitamin D deficiency affects up to 50% of the general population and is even more common in people with obesity (it's fat-soluble and can be sequestered in adipose tissue). As you lose weight and absorb more D, supplementation is still important, especially in low-sunlight months. Pairing with K2 directs calcium into bones rather than arteries. Aim for 2,000–4,000 IU D3 daily.
Magnesium is involved in over 300 enzymatic processes including muscle function, sleep quality, and insulin sensitivity. It's one of the most common deficiencies in the general population and can be depleted further on a low-calorie diet. Signs of low magnesium include muscle cramps, poor sleep, constipation, and anxiety. Take 200–400mg of magnesium glycinate or citrate at bedtime.
If your dietary fat intake is reduced on GLP-1 (which often happens alongside reduced portion sizes), omega-3 intake from fatty fish may fall below optimal. Omega-3s support cardiovascular health, reduce inflammation, and help with mood regulation. 1–2g of combined EPA+DHA daily from fish oil or algae-based supplements.
Reduced red meat consumption and lower overall food intake can compromise iron levels. Low iron causes fatigue, hair loss, and poor exercise performance. A ferritin blood test is the most reliable way to assess iron status — don't supplement iron without testing first, as excess iron is harmful.
Metformin (often prescribed alongside GLP-1) is a well-known B12 depletor. Plant-based dieters already face higher deficiency risk. B12 deficiency causes neurological symptoms and anaemia. Sublingual B12 or a B-complex supplement is low-cost insurance.
A baseline blood panel before starting GLP-1 — covering vitamin D, B12, ferritin, magnesium, HbA1c, and a full blood count — gives you a baseline to compare against at 6 and 12 months. Targeted supplementation based on actual deficiencies is safer and more effective than broad supplementation.
Getting 100g+ of protein daily on a reduced appetite is hard. Strategic timing makes it more achievable — and more effective for muscle preservation.
Medication helps with appetite. But the mental skills for sustainable weight management — resilience, flexibility, self-compassion — must be built intentionally.
People who share their journey with a community — online or in person — consistently achieve better outcomes. Here's why, and where to find yours.