Dietary fat is fat from food — an essential nutrient and also the carrier that transports other nutrients through the body. It supplies the essential fatty acids linoleic and alpha-linolenic acid, which the body cannot make; it enables the absorption of the fat-soluble vitamins A, D, E, and K; it cushions organs, insulates against cold, and provides the most concentrated energy of any macronutrient at 9 kilocalories per gram. The type matters enormously: unsaturated fats from oils, nuts, and fish support heart health, while excess saturated and industrially produced trans fats raise cardiovascular risk. Dietary fat also shapes food itself — carrying flavour, creating tenderness and flakiness, and triggering satiety. Nutrition debates swing between vilifying and celebrating it, but physiology is settled: the body needs fat, in the right kinds and amounts.