Why protein is the priority macronutrient
Rapid weight loss — the kind GLP-1 therapy produces — comes with a measurable risk of lean-mass loss. According to NIH research on protein and muscle preservation, without adequate protein and resistance training, roughly 25–40% of the weight lost can be lean tissue, which lowers resting metabolic rate and predisposes to regain when therapy is paused or discontinued.
How much protein per day
The 1.2–1.6 g/kg/day range is the consensus from rapid-weight-loss and sarcopenia research, including the PROT-AGE Study Group recommendations on PubMed. For a 90 kg adult that's 108–144 g. For a 70 kg adult, 84–112 g. Spread across 3–4 meals at 25–40 g each is enough to maximally stimulate muscle protein synthesis at each feeding.
Practical sources
High-leverage, easy-to-tolerate options: whey or casein protein shakes (~25 g per serving), Greek yogurt (~17 g per cup), cottage cheese (~25 g per cup), chicken breast (~25 g per 100 g), eggs (~6 g each), canned tuna (~25 g per can), tofu (~10 g per 100 g). The Mayo Clinic protein primer is a useful reference for whole-food protein densities.
When solid food won't fit
Liquid protein is the secret weapon of GLP-1 nutrition. On dose days, many patients can't tolerate more than 100–200 g of solid food per meal. Two protein shakes plus one solid-food dinner often gets the daily total to target without forcing meals you don't want.