Along with carbohydrates and protein, fat is regarded as a macronutrient that imbues the body with nutritional energy. Fats are composed of fatty acid strands that are 1 or 2 links of hydrocarbons and acids. Unsaturated fats are strands missing some hydrogen molecules and are considered the best fats to consume as they do not affect the cardio-vascular system as adversely as do saturated fats (strands saturated with hydrogen molecules). Diets high in saturated fats such as butter, cow milk, coconut oil and animal fat are linked to incidents of heart disease.

Fatty acids in moderation are necessary for the body as they aid in cell function, organ insulation, body temperature regulation and mood regulation. Omega 6 essential fatty acids are found in green leafy vegetables and plant oils such as soy, sunflower and corn oil while Omega 3 fatty acids are found in fish such as tuna, trout and salmon. The latter fatty acids are needed for energy storage and skin and hair health.

Digestive breakdown of fat, moreover, yields chemicals that are converted by the liver and used to produce glucose. The transportation and absorption of certain vitamins such as A, E, K and D is also facilitated by fat consumption.

It is important to note, however, that fat should be limited to 30% of an individual's total caloric intake. As one gram of fat is 9 calories, a diet of 2000 calories would include 67 grams of fat.