Maintaining weight with an exercise regime

I am begining a new exercise regime and I would like to maintain my weight, how can I do this?

Protein powder added to muesli, fruit, yoghurt or a smoothie. Purchase one which has no added sugar, artificial ingredients or preservatives and one which has a balanced amount of protein and carbohydrates.
A rice or Soy based protein powder which you can add to water, juice or a fruit smoothie.
Add yoghurt and nuts to a fruit smoothie or have a handful after exercise.
Egg white albumin powder contains high amounts of nutritional protein as an alternative to dairy based protein powders.
Add ground up linseeds, soy and almonds (LSA) to fruit, smoothies, yoghurt, pancakes or cooking.
Eat more protein in your diet - fish, organic chicken and meats, nuts and seeds, tofu and free range chickens.