It is universally held that you need a "balanced" diet with vitamins, protein and starch in the "right" quantities each day and that you need to eat a moderate amount at regular intervals also each day. This is the route to poor health.
To be fit and strong, your digestive system needs to get used to a variety of conditions. Sometimes you may eat more than you need. Sometimes you should go hungry. You should not eat when you get hungry, but when the thought arises in your mind to eat. All first thoughts are given to you by God. All of us should be moving towards becoming vegetarian. There is so much violence in the world that the least we can do is to help stop the slaughter of other living beings. Non-injury or minimizing injury to living beings is the first principle of yoga [ethics or yama]. There is no greater consideration. After about one year of being vegetarian, your hankering for meat and seafood almost vanishes. You should ideally wake-up one morning and say to yourself "henceforth I will be vegetarian".
You should not worry about what you eat. Instead, choose readily available vegetarian food, fresh food that is light to digest. When you think of food, eat a little until you are no longer hungry, unless there is no food available. In that case wait until the next convenient opportunity that God gives you to eat.
As you progressing yoga, you become more sensitive. Water these days is heavily polluted in spiritual terms. It is better to have liquid such as milk or yogurt that has been purified by a cow, or fruit juice. Even after subsequent pollution by man, such liquids retain much purity. Drink as and when the thought arises in your mind, unless there is nothing to drink, when wait until a natural event happens [passing a shop, for example].
Once you are on the path of karma yoga, God is looking after you. You do not need to worry about lack of starch or protein or vitamins. If you need starch, you will get a thought to have some starch.