According to the principal nutritional indications, fats should cover between 25% and 35% of total energy intake by an individual because, if ingested in the appropriate quantities, hold a number of important roles: they provide essential fatty acids (such as linoleic acid and alpha-linolenic acid) and fat-soluble vitamins (A, D, E and K); they represent a major source of energy; promote a sense of satiety due to the effects on the slowing of gastric emptying and reduce, for the same reason, the bioavailability of carbohydrates (and, therefore, the glycemic response); finally, they improve the flavour, odour, and texture of the foods. But all fats, as well as carbohydrates, are high in calories. And if you consume more calories than you need you gain weight.

The World Health Organization estimated that excess weight is responsible for 21% of cases of ischemic heart disease, 23% of ischemic strokes, 58% of type 2 diabetes and 39% of cases of hypertension. Obesity also increases the risk of certain types of cancer, as well as the risk of non-fatal diseases, such as joint problems and infertility.

Saturated and unsaturated fats differ in the composition of their molecule: a saturated fat has individual chemical bonds between the atoms that compose it, while an unsaturated fat has at least one double bond. It is this double bond that makes it unsaturated, incomplete, because there would be the possibility of adding hydrogen to the double bond to make it saturated, i.e. devoid of space for new additions. Liquid fats are composed mostly of unsaturated fats, such as olive oil which is a monounsaturated (i.e. has a single double bond) and solids (for example margarine, butter or palm oil), are for the majority saturated.

Fats are found in both in plant-based foods, and in the food of animal origin. With a few exceptions, such as tropical oils (palm and coconut), vegetable fats are mostly of the unsaturated type, while among animals fats are composed for about half the saturated fatty acids.

For several decades dietary guidelines have recommended reducing the consumption of saturated fats, considered to be responsible for some cardiovascular diseases, thus leading to a significant reduction in the consumption of animal products, especially meat based. It should be remembered that saturated fats are not all the same, because some contribute more than others to cardiovascular risk, in addition to the increasing evidence of the role of carbohydrates for these conditions. Furthermore, the major constituent of the saturated fat content of meat, stearic acid, has been shown to have a neutral effect on total cholesterol and LDL cholesterol (low density lipoprotein).

The growing attention to the quantity and quality of fats contained in meat has pushed producers and breeders to study production practices (cutting techniques) and breeding (animal diets), in order to generally produce more lean meat and also to favour the composition of more balanced fats. Cooking can have a powerful influence on fat in meat, as well as in the composition of the fatty acids.

Some authors have demonstrated significant reductions in the amount of fat in different cuts of meat cooked on the grill or in the pan without any added fats. In particular, with regard to the fatty acid composition, there was an increase in the polyunsaturated/saturated ratio, probably because polyunsaturated fatty acids are part of the cell membrane and therefore tend to remain in the meat fibres.

The Sustainable Meat Project