Salmon & Other Oily Fish

Salmon is the most nutritionally strategic protein on this list because Harvard Health found GLP-1 users develop measurable nutrient deficiencies within a year — vitamin D deficiency in 13.6% of them. A 100-gram serving of cooked salmon supplies 20–25 grams of protein and over 70% of your daily vitamin D, plus omega-3 fatty acids EPA and DHA that you cannot get from chicken or yogurt. These omega-3s are anti-inflammatory and support heart and brain health when total food intake has shrunk. Salmon's healthy unsaturated fats digest more comfortably than saturated fat in fatty meat and add satisfying richness. Compared to skinless chicken (#3), salmon trades protein density for a major micronutrient upgrade, providing 70% of daily vitamin D versus chicken's 0%. Compared to eggs (#2), salmon offers superior omega-3 content and vitamin D levels but costs more. Canned salmon is a budget-friendly alternative that keeps the same protein and vitamin D — unlike canned light tuna, which carries far less vitamin D. A modest fillet two or three times a week is one of the highest-value habits a GLP-1 user can build.