She’s mentioned a few times about having disordered eating and I’m guessing it’s something to do with bingeing.
Gaining and losing weight is really very simple. You have to either consume more calories or fewer calories than your body uses each day.
So for example, if she’s 5”6 and weighs 20 stone, (just a guess), eating around 2408 calories a day would maintain her weight.
She’s clearly gained quite a lot of weight in the last year and therefore must be eating 3000+ calories. I don’t think she’s eating thousands of calories worth of her salads and vegetable dishes every day.