The Depo shot DOES make women hold on to every calorie, because the brain thinks the body is pregnant.
I foolishly tried it when it first was approved and packed on 15 lbs. within the 1st month of getting the shot-with no change in my then usual exercise or eating habits. I didn’t bother with a second shot. Those 15 lbs. were a bear to shed, it seemed different than just plain ol’ weight gain.
I have a family member who used the Depo shot for years and now the once slender, cute newlywed is carting around an extra 80 lbs. She’s also had a host of fertility problems for years after quitting it-probably due in part to the weight gain-caused from monkeying around with her hormones.
In both cases our health care ‘professionals’ insisted the drug DID not cause weight gain...but to me it seemed like a no-brainer!
I took two rounds of Depo shots to try and cure some pain my doctors originally thought was related to ovulation. Both my doctor and her nurse warned me about weight gain during our discussions about possible treatments — they told me (this was about 1 1/2 years ago) that most women on the shot will definitely gain between 5-15 pounds (obviously some will gain more, and some less). I think you’re right that while the shot tricks the body into not ovulating and such it starts taking in the extra calories, but there’s no baby to “feed” so it just goes into storage...
As for me — I’m not on the Depo shot anymore (was off that after 6 mos.), but due to 2 of my other medications I’ve put on a TON of weight (used to be 125-130, but have gained like 50 pounds now in the last few years). Very depressing, and VERY hard to get rid of. Like you it’s not like my diet has changed - just my metabolism being affected by my medications, and of course I’m over 35 now so that doesn’t help either! LOL