There are only two fatty acids that the body can not make and these must be ingested in the diet to maintain these essential fatty acids. All other fatty acids can be created from other types of food in the diet. The minimum dietary fat intake is that which provides the daily requirements of the essential fatty acids; it only takes 2 to 4% of the daily caloric intake as linoleic acid (an essential fatty acid) to meet this requirement.
Because fat is such a precious energy reserve, the body will preferentially burn up all its carbohydrate reserves before it will initiate any significant breakdown of the fat reserves. This is why limited exercise does not achieve significant fat loss. Exercise has to be maintained for a long enough period of time to burn up all the other energy reserves before you start to loose fat at a significant rate. So as the carbohydrate (glycogen) reserves start to run low with exercise, the fat burning mechanisms kick in and it is the carbohydrate that fuels the burning of the fat. In essence, fat burns in the flames of the carbohydrates reserves, but only as a last resort.
Low fat diets seem to make biochemical sense. There is a great deal of scientific support to limit the amount of fat in a diet. The role of fat in the normal diet is complicated because there are different types of fat. When scientists look at fat, they break into its smaller parts, just like the body does. These smaller units are called fatty acids and different fatty acids have different effects on health. In simplistic terms, there are saturated fatty acids and unsaturated fatty acids. This has to do with the fatty acid chemical structure.
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