I am a food with 5 letters.
Take away my first letter, and I become a form of energy.
Take away my first two letters, and I become something you need to live.
Rearrange my last three letters, and I become something you drink.
Solution
Wheat
“Heat” is a form of energy, you need to “eat” to live, and “tea” is a drink.
You don’t need “eat” to live, you need “to eat” to live.