If you are on 1300 calories per day can you eat what you want if it is within your calorie allowance?

You will have to eat proportional amounts of proteins, fats, and carbs still. If you are not eating proteins, your heart will have damage, as well as other muscles. The proteins in these muscles will be utilized, and the muscle will waste away.

Conversely, if you have way too much calories from protein, you will have kidney damage from the high protein metabolism.

Protein 25-35% of daily calories (Egg or non-fried chicken)

Fats 10-20% (maybe one twinkie)

Carbs roughly 45-55% of meal (Carrots are a good carb)