Diet is the sum total of all nutrients we consume on a dailybasis. The three major macronutrients which we consume generally are carbohydrates,fats and proteins. The fats weconsume are first broken down into free fatty acids and glycerol, now thesehave two pathways:1. They areused in the general metabolism of the body and provide the maximum amount ofATP when compared to other macronutrients when they undergo complete betaoxidation and go through citric acid cycle.2.
The excessfatty acids go into the free fatty acid pool and these are converted into fatfor storage by lipogenesis.These fat stores can be converted into fatty acids andreturned to the free fatty acid pool, when required by lipolysis. The carbohydrateswe consume are first broken down into glucose and normal range of plasmaglucose is maintained in our body which varies depending on our intake of thesame, apart from that the following routes can be taken up by glucose in ourbody:1. Some amountof glucose goes into use in the general metabolism of the body by the processof glycolysis which generates ATP and NADH for use in our body. Brainmetabolism exclusively uses glucose for its metabolic processes.
2. Some amountof glucose is excreted in the urine which is around 0 to 0.8 millimoles/litre.A higher amount of excreted glucose in urine is an indication of certainpathological conditions like Diabetes mellitus.3. In animals,excess glucose in the body is stored in the form of glycogen by the process ofglycogenesis, which can be broken down into free glucose and released intocirculation by the process of glycogenolysis as and when needed by the body.4. More excessglucose in the body maybe stored as fat by the process of lipogenesis.
The proteins we consume in our diet areabsorbed in our body after being converted into amino acids and can have thefollowing fates in the body: 1. Mostly theamino acids are used in synthesizing various proteins in the body.2. Sometimes,under certain conditions of low glucose levels in the body, the amino acids canbe used to produce glucose by the process of gluconeogenesis. Generally, ina normal human body, the first and preferred source of energy are thecarbohydrates, followed by fats and then the proteins. Breakdown of proteinsfor glucose and hence energy, occurs in extreme starvation conditions and alsoin certain diseased conditions like Kwashiorkor.
Maintaininga balanced diet by taking the right proportions of each of the above mentionedmacronutrients along with the essential micronutrients is important for ahealthy and well-functioning body.