They have the highest energy value of all the nutrients. There are saturated (pork, tallow, butter) and unsaturated, monounsaturated (olive oil, almonds, hazelnuts) and polyunsaturated fats (flax, fish, chia seeds).

Unsaturated fatty acids should be present in the diet, because rhey are fraught with vitamins (A, D, E and K) and essential fatty acids, which have beneficial effects on the condition of blood vessels. Trans fats (industrial fats) are formed by hydrogenation of liquid oils (exposure of oil to high temperatures and re-usage of the same oil), during which it gets solid structure. Most of them are present in French fries, potato chips, maragarine, fried foods, pastries, donuts, waffles, etc. Saturated fatty acids and trans fats lead to a build up of fatty deposits in blood vessels leading to hyperlipidemia (elevated levels of bad cholesterol-LDL), myocardial infarction, stroke and other diseases caused by the narrowing of blood vessels. In order to increase good cholesterol HDL, daily intake of omega-3 and omega-6 fatty acids is necessary from marine fish, cold-pressed vegetable oils and fresh salads rich in cellulose. Aerobic physical exercises 3-4 times a week contribute most to raise HDL.