Am I right that, if I (early twenties, 36 BMI) have no other health complications, it makes sense to wait to see what the long term effects of these drugs are?

Am I right that, if I (early twenties, 36 BMI) have no other health complications, it makes sense to wait to see what the long term effects of these drugs are? If I knew it was safe in the long term I’d take it in a heartbeat. However, I’m concerned that there could be long term issues with the drug (perhaps a resistance/“yo-yo” effect where the potency wears off and I gain back my original weight plus more than I would have otherwise over, say, 10 or 20 years). Is that the sort of thing that’s in the realm of the possible/plausible or is this more like a vaccine where there are some strong theoretical reasons why we don’t expect it to have long term issues?