People who lost a lot of weight then gained it back, what was your mistake?

celebrated by eating everything in sight. regret came fast

stopping tracking calories after I lost weight

Drinking beer

Falling back to binge eating

Work changed my schedule to 12-hour shifts. It's really hard to maintain healthy eating and exercise habits, so of course you stop exercising and eat junkfood because you're too tired.

poor consistency

Two weight loss surgeries, every diet and weight loss drug ever invented (it seems like anyway), lost a ton of weight and then gained a lot back. Reason? I was diagnosed with lipedema last year. My stomach is flat, the rest of me lumpy, bumpy and look fat. However, short of surgery, which I cannot afford, there is little I can do to improve this. There are few conservative measures, but this disease is not curable, diets and exercise have little to no effect on it, and it is generally progressive. So, my mistake, is not MY mistake, it is genetics and doctor's dismissing my issues with "not wanting to lose weight bad enough". Not exactly what you were expecting to hear OP?

Chose a diet that wasn't sustainable, rather than making a nutritional life change.

It’s just biology bro

I treated my weight loss like a temporary prison sentence with a release date instead of a permanent shift in my identity. Once I hit the goal number I stopped doing the work because I had not actually addressed the emotional reasons why I was using food as a shield in the first place.

Moved to a new job in a new state. Way hotter (less inclined to run outside or even go work out), way more access to fast food, more stress, and lived by myself vs having roommates.

Treated my weight loss like a destination and not a journey. I was raised on very poor eating choices and it’s taken me decades to reverse that. I have finally been able to maintain my weight loss for over a year because it’s not a goal, it’s my lifetime privilege to keep working on me.

I probably get a lot of hate for this. Losing weight is "easy" (I know its not), you only have to intake less calories then you burn. Less calories eating, and the energy comes from fat. You can do alot to increase calorie usage like exercise, but it always come down to simple math: eat less calories then you burn = weight loss. If you take on weight afterwards its because you calorie balance change. Either you are burning less og eating more.