But how well you maintain your weight seems unrelated to how you lost the weight. You can lose it rapidly, slow. Smart or stupid. Aggressively or conservatively. How well you maintain it is an independent issue.
Exercise can take the calories out.
My weekly fast lowers the calorie count going in. But it's not for everybody. And like all diets, it is filled with delusion. Fasting one day doesn't give you license to gorge the next. Fasting through half a day and then sitting down to a dinner of lamb chops and a chocolate torte is self-sabotage.