Humans require food to supply their energy needs. The energy from food comes from three basic macronutrients and for many adults, alcohol. A multibillion dollar industry exists in the US and the developed world promoting various diets that claim that eating specific proportions of macronutrients will promote health (i.e. Atkins, Paleo-, Mediterranean Diets). Describe the amount of energy obtained from various n,macronutrients and how the specific items within each macronutrient class (e.g. plant vs. animal protein; simple vs. complex carbohydrates) influence their metabolism and risk of chronic disease