It’s not technically a food, but hydrating with plenty of water is necessary to digest high-energy foods. Drinking water before and after meals helps to break down food and transport energy and nutrients throughout the body.¹² Without proper hydration, you may feel more tired and have difficulty concentrating.¹³  

Sources:

[12] https://mayocl.in/2JhfsCP

[13] https://bit.ly/2EUvq8X