The food you eat does not contain ATP that is ready for you to use. First you must break carbon-based molecules to produce ATP.
The amount of ATP molecules produced depends on what is broken down. Generally it is carbohydrates, but lipids or proteins can also be broken down to produce ATP. Glucose when broken down makes about 36 molecules of ATP.
This is a good place to watch the Crash Course video, ATP & Respiration, https://youtu.be/00jbG_cfGuQ?list=PL3EED4C1D684D3ADF there are some things in this video we'll cover later in this unit, for now pay attention to the process of ATP use and production.
Fats store the most energy, about 80% of the energy in your body is stored in fats. And when broken down fats yield more ATP, about 146 ATP from one triglyceride!
Proteins are least likely to be broken down to make ATP, when they are they produce about the same as a carbohydrate (36 ATP).