1) I have no reason to think the carbon intensity per calorie would change

2) it doesn't take much overeating per day to build up, so I'd assume semaglutide based weight reduction reduces calorie intake by about 25% per day unless someone gives me a study (can't find myself as search results biased to news not science)

and 3) all agriculture combined is about 12% of emissions

multiply together and that would be about 3% of global emissions, which is a start, but not sufficient — we need to target 99.9% for long term sustainability