How are fats structured?
All macronutrients occur as structures into which smaller individual parts have come together. Our dietary fats are made up of triglycerides and three attached fatty acids. Based on their variety and quantity, fats are classified by chain length into short, medium and long chain fats. Another classification is based on the number of double bonds within the chains, resulting in the groups of saturated (no double bond), monounsaturated and polyunsaturated fatty acids (one and several double bonds, respectively).
The functions of fats
The best known and at the same time most unpopular function of fats is probably that they serve as energy stores - what we see as unwanted fat pads. But energy stores fulfill an important role when energy needs to be available for long periods of time or in a state of starvation. They provide nine calories per gram. Not visible to us is organ fat, which lies protectively around our organs as a pressure cushion. In addition, body fat prevents the loss of heat because it acts like an insulating layer. The most significant functions also include the synthesis of bile acid, vitamin D and steroid hormones, as well as the transport of fat-soluble vitamins and the supply of essential fatty acids (i.e. we have to take them in through food). Essential fatty acids perform numerous functions during inflammatory processes and in blood clotting, among others. Fats are also used to make components for our cell membranes, making them important for the central nervous system. Last but not least, fats are an important flavor carrier.
The digestion of fats
The digestion of fats is conditioned with the mechanical comminution by chewing in the mouth and by natural movements in the stomach. To a small extent, fats are already broken down by enzymes. They are then emulsified, i.e. broken down into smaller droplets, first in the stomach and later in the small intestine by bile acids. Only then can the fat-digesting enzymes begin to break down the fatty acids. Breakdown in the stomach is a necessary prerequisite for the further digestion process, which is why high-fat foods remain in the stomach for a long time and become satiating.
Recommendations for fat intake
Fats should make up about 30% of the calories you consume during the day. Now that may sound like a lot at first, but since fats provide slightly more than double the calories per gram compared to carbohydrates and proteins, it is the least represented macronutrient in terms of quantity.
Here's an example:
- Energy requirements = 2100 calories per day
- 30% via fats = 630 calories : 9 calories per gram of fat = 70 g of fat per day
- Approx. 15% via proteins = 315 calories : 4 calories per gram of protein = 78.75 g of protein per day
- The remaining 1155 calories can be obtained from carbohydrates. At 4 calories per gram of carbohydrates, that's 288.75 g per day.
Fats should preferably come from plant sources, such as oils, nuts, seeds or avocado.