Which foods should i be eating while I'm going to the gym to lose weight and tone up?

Good, nutritious food. Trying to gain muscle and lose weight at the same time is a bit more difficult than attempting one thing at a time, but in terms of overall health, it's be much better. If you only wanted to gain muscle, you could consume a massive amount of calories all the time, but you'd gain fat too. On the other hand, you could significantly restrict your calories to lose weight, but your body needs calories to build muscle. Consuming a reasonable amount of calories from nutritious foods with regular cardiovascular exercise is going to be your best choice. The biggest issue when trying to both lose fat and gain muscle is the fact that the body will breakdown muscle as an energy source under certain conditions, especially when deprived of other energy sources (such as carbohydrates). From an anecdotal perspective, I've never encountered any noticeable loss of muscle mass while losing weight- I've gained muscle mass, actually. I make sure to always eat when I'm hungry, and certainly before and after workouts. I'm not an expert on when the body prefers to catabolize fat or muscle, but I believe that outright caloric deprivation, especially after exercise when the body needs additional energy to recover, will promote muscle catabolism. Your body needs a constant supply of energy and will literally start dissolving itself if it's in need of energy. "Shocking" your body, exercising with limited available calories is probably not the best and might promote breakdown. A small but definite caloric deficit everyday, leading to gradual fatloss is probably the best. Fruits, vegetables, whole grains, lean proteinand sources of monunsaturated fat and omega-3s are all good choices. Protein is certainly essential, but you don't need to go chowing down on protein shakes and massive amounts of supplements. ~.73 grams of protein per pound of lean body mass a day is the absolute most I've seen any study support for anyone-chances are, you're already consuming that much, if not more. Consuming a bit of protein before a cardiovascular workout might possibly limit muscle catabolism, as you'll have a much morereadily available, though identicalenergy source as your muscles.