You don't automatically drop weight super quickly on drugs like Mounjaro or Saxenda, etc....I went back on Saxenda and lows carb seriously about a month and a half ago after regaining all of the weight I'd lost the last time. I will always be fat unless I can stop eating carbs, and I always give in eventually because life sucks without carbs. I started over 200 pounds. So, it's not like I'm 120 and didn't have much to lose. But I have never been under 160 in my adult life, and that was right before my wedding.
I lost about 10 pounds super quickly--like in the first 2 weeks. Mostly water. Then it's been about a pound a week. I'm in my later 40s. I've definitely been eating under 1,500 calories a day--usually less. So, it's not like these drugs will just melt weight off your body. They just make it easier not to give in to cravings and make better choices.