Something doesn’t add up. If youre TDEE is truly 2050 and youre truly eating 1400 and not losing weight then something isn’t right. Either youre eating more than 1400 or youre TDEE isn’t 2050. Do you include what you drink as well? Fizzy drinks, alcohol as part of your calories? Eating 2050 calories of sugar will not have the same effect as eating 2050 calories of broccoli. So look closely at what you eat as well as how much you eat.

Ok you didnt mention any potential thyroid problems. Easy enough to have a function test done. If that come back negative then look for the more obvious reasons for the weight gain.

On the assumption that everything is OK regards thyroid function. If you intend to run a 500 calorie deficit every day then youre not doing 5:2. Its just a typical calorie restricted diet like every other diet. And they don’t work long term. About a 5% success rate at best. In response to this continual restriction your body will lower its metabolic rate to conserve energy, even if your thyroid function is OK. So given the choice between a deficit of 500 cal every day for a week (i.e. 3500 deficit for the week) or running a 3500 cal deficit over two days and then eating normally the other 5, Id take the 5:2 system every time. No contest. Ive lost 48 pounds from 202 to 154. Ive been in maintenance since March 2016. I still water fast every Monday, no exceptions. On the other days I eat normally. I don’t calorie count at all. My satiation signals are very strong. I very rarely eat junk foods. I consider all grain based foods processed junk. I tend to be a lot stricter than most, but there are others on here that are as strict with their food intake. I don’t find it a chore because I don’t think Im denying myself anything.

Good luck with it.