Basic Nutrition
Both protein and carbohydrates have 4 calories per gram. Fat has 9 calories per gram and alcohol has 7 calories per gram. A quick method for determining how many calories you need to take in daily for your body to function at rest (Basal Metabolic Rate or BMR), is multiplying your weight by 10. For example a 200 pound man would have a BMR of 2000cal/day. In addition the body needs energy to perform daily activities. General movement has often been estimated to burn about 300-500 calories per day. So if the 200 pound man with a BMR of 2000cal/day burned 500cal/day from general activities and 500 calories a day were spent exercising at the gym, he would need to consume a total of 3000 calories a day to maintain his bodyweight. If he wanted to lose weight, he could consume slightly less calories or do slightly more physical activity. If his goals were to add lean mass, he might want to consume an extra 300-500 calories per day.
The American Heart Association recommends that dietary fat intake should be less than 30% of total calories (Saturated fat should be less than 10% of total calories. Polyunsaturated fats should be up to 10% of total calories. Monounsaturated fats should be 10-15% of total calories.). Dietary carbohydrate intake should be 50-60% of total calories. Dietary protein should be 10-20% of total calories. Cholesterol intake should be less than 300mg/day. Sodium intake should be less than 3,000 mg/day.
If you are a little unsure of what you should be eating and in what quantities, it would be beneficial to meet with a dietician to develop an eating plan suited towards your goals.