This is based on my own personal experience and resulting opinions, so please accept it as such - I'm not a doctor or nutritionist. First, if you have to work out to maintain a decent weight/shape, you're eating the wrong foods. I dropped my weight from 230 lbs to 185 (I'm 6'1) in six months by adhering to one simple rule: Don't eat processed foods. Fruits & veggies, nuts & berries, home-cooked bread, meat & fish - all good. Anything that comes in a box, can or jar - bad. The food supply has changed radically in the last 30 years, and we're simply not biologically adapted to tolerate it that well. The result is weight gain and sickness - high blood pressure, cholesterol, diabetes, etc. etc. Eat like a cave man, man! If we weren't eating it 5000 years ago, we probably shouldn't be eating it today.
Full disclosure: That was 3 years ago. I've added back into my diet small amounts of cheese, eggs, and some staples that do come in bottles - soy sauce, ketchup, mayonnaise, and the like, but I try to choose products containing the fewest possible chem-lab ingredients. I now maintain a weight of 190-195. Oh, and all my health problems from 3 years ago have disappeared, including that sometimes-painful bump on my wrist.