generally things need to have carbon and hydrogen and oxygen(elements) in them together (to make a compund) if they can be used as a source of energy by nature....there are exceptions but this is a good rule of thumb
thing like protein, fat and carbs have carbon and hydrogen as well as oxygen in them. They can be broken down by the body and in doing so create carbon dioxide and water
things like sodium are minerals we need....they tend not to have a carbon, hydrigen and oxygen in them and can;t be used as energy. they may have roles in the way the energy is produced but they produce no energy themselves. the big players are protein carbs and fat, very few other molecules break the trend