Yes. Much of what provigil and stimulants do is put you in a state where your body uses up more of your available energy (hence the weight loss aspect of them).

Yes. Much of what provigil and stimulants do is put you in a state where your body uses up more of your available energy (hence the weight loss aspect of them). This may be a totally illiterate statement, but generally speaking any substance that causes loss of weight (or causes weight to stay the same despite increased consumption and lack of excercise) due to metabolism is going to also cause greater ability to concentrate and a greater mental stamina. One way you can eat the same amount of calories and either lose weight or gain no weight is by reducing complex carbs in your diet. Avoid things that are high on glycemic index and you won't feel slow: this doesn't meant cut out all carbs! Eat whole wheat bread, brown rice, dark chocolate if you have carb cravings just lessen the white wheat, high fructose corn syrup, white rice etc... Combined with regular excercise (at least 3 times a week, at least 45 minutes each time -- with at least 30 minutes of that being cardio) you will feel a lot better and be (or remain) in better shape (if you are worried about losing too much weight or muscle mass simply eat more - but more calories, not more carbs).