answer:You should not preoccupy yourself with a minimum caloric intake or eating fat free and low carb, low calorie food. What you should really do is eat in moderation, the reason that there are recommended serving size on most products is to give you an idea of what should be good for the average guy of 170ish lbs. The best thing to do is be active and get out and walk, mabye go for a run and eat in moderation. It is totally possible to lose weight on a fast food diet, you just need to be active and eat in moderation. But for a good minimum, around 2500–3000 calories should be good, but try and be active. One other good thing is to find a calorie charing website that you can put in your daily activities and it will give you a customized read out of minimum and maximum caloric intakes per day. — P.S. Sorry if the beginning sounded like a rant, i just don’t like it when people think that by eating less they can lose weight. It is a combined effort or eating less and exercising more. Also I am not a dietitian, I am actually a high school student, but I do have some experience with this stuff, but do look at a calorie plotting website they will help you with making good decisions