Not all the weight coming off is fat
GLP-1 medications work. They also come with a problem that rarely gets mentioned at the point of prescription: a substantial proportion of what you lose is lean tissue rather than fat. That's addressable, but not by accident.
How much lean mass is at stake
Across trials, lean mass has accounted for roughly a quarter to nearly half of total weight lost, varying by medication and study. Some lean-mass loss accompanies any weight loss — that's normal. The question is whether you land at the top or bottom of that range.
Two things move the number
Resistance work and adequate protein. Together they can reduce lean-mass loss substantially. Separately they do much less: protein without a stimulus to use the muscle, or training without the raw material to rebuild, each leave most of the benefit on the table.
Eating enough protein is harder on a GLP-1
These medications work partly by reducing appetite, which makes hitting a protein target genuinely difficult rather than merely inconvenient. A common target during weight loss is around 1.4 grams per kilogram of goal bodyweight. Front-loading protein earlier in the day, when appetite tends to be less suppressed, is a practical workaround.
The scale can't tell you whether it's working
Weight falling tells you nothing about the composition of what's leaving. A strength measure can. If your 30-second sit-to-stand count holds steady or climbs while the scale drops, the tissue you're losing is overwhelmingly the tissue you wanted to lose. If it falls alongside your weight, that's worth acting on.
Plan for the bad days
Nausea after dosing is predictable rather than random. A programme that expects you to perform identically every day will break on those days and take your consistency with it. Dropping to the smallest version of the work on a nausea day, deliberately and without guilt, preserves the habit.
FAQ
How much protein should I eat on a GLP-1?
Around 1.4 grams per kilogram of your target bodyweight is a commonly used figure during active weight loss. Anyone with kidney disease should confirm a target with their clinician before increasing protein intake.
Do I need a gym to protect muscle?
No. Resistance training means asking muscle to work against meaningful load. Standing repeatedly from a chair, then from a lower chair, then holding something heavy, is a legitimate progression that needs no equipment.
How can I tell if I'm losing muscle?
Without a DEXA scan you can't measure it directly, but you can track function. A strength measure that holds or improves while weight falls is a good sign; one that declines in step with your weight is a signal to add resistance work and protein.
Should I exercise on days the nausea is bad?
Do the smallest version rather than nothing, if you can manage it at all. Consistency across weeks matters far more than any single session, and forcing a full session through nausea is a reliable way to start associating the whole thing with feeling ill.
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