I lost weight in my late 30s by reducing my calories to 1800 a day.
Now mid 40s and I put around half of the weight I lost in my 30s back on. Went back to dieting but nothing was shifting on 1800 so dropped to 1300 and have lost almost 2 stone.
I am much more active now than I was back then. I train and teach martial arts 4 times a week, go to the gym, run etc so I presume as I've gotten older my body just naturally burns fewer calories so to lose weight I had to drop the calories further.
I do weigh everything I eat, even down to the butter on my toast. But I've enjoyed the challenge and have focused on finding healthier choices. I still have dinners out or alcohol if I want it but find more often now I choose healthier choices because I want to.
Just dont send an Eton Mess my way, I will lose all semblance of control 🤣
Look, broadly speaking you're right. It's energy consumed vs energy used. But there is a lot of nuance. Do some people just over eat and make bad choices.....of course. Do some dieters actually not understand what they're eating and fall foul of hidden calories......probably. But genetics plays a part, medical conditions play a part, even medication people are on play a part. Ever taken steroids, I ballooned on them and yet ate very little as they made me so sick!