Because of fast food you are getting fat, you have to avoid fast food if want to reduce weight. Fast food will give you empty calories, which on regular consumption will turn into fat storage within body. Constipation might be there as you are not consuming fruits and vegetables. I suggest you have regular home made food. Keep your diet healthy. Frequent small meals are better than 3 large meals. Drink plenty of pure water. Make habit of eating flax seeds (alsee beej) 1 tea spoon after every meal this will revert back your weight. For perfect diet you can take appointment. If interested message me personally.