I feel you, dear. I gained 21kgs in 6 months when my hypothyroidism kicked in due to eating high-carb food. Back then, I only did calorie restriction and I did lose weight fast. However, the moment I started eating more than my required calorie intake, I gained the weight back in a blink. There’s really a big difference when you eat healthy and exercise at the same time. I’ve read an article before that people who tend to exercise and eat healthy are less likely to gain the weight back. I never really believed that until it happened to me.