In-depth analysis of fat (Part 2): Seven core physiological functions of fat

From the above explanation, we know that fat is not only an important component of human tissues but also one of the main substances providing energy, essential for life. Dietary fat is digested and absorbed in the stomach and intestines, and most of it is converted back into fat. It is mainly distributed in the subcutaneous tissue, greater omentum, mesentery, and around the kidneys. The amount of body fat varies depending on each person's nutritional status and energy expenditure. Currently, body fat percentage is generally used to measure the proportion of fat in the body, which we will discuss in detail later. Fat plays a vital role in life, with numerous and complex functions. The presence of fat provides the basis for cell existence and allows the cell membrane, composed of lipids, to separate the cell from its surrounding environment. It is no exaggeration to say that without fat, there is no life. So, what exactly are the functions of fat? Let's take a look.

The main functions of fat are: First, fat is an excellent energy storage substance within cells, primarily providing the body with heat, protecting internal organs, maintaining body temperature, and participating in various metabolic activities. Second, from a nutritional perspective, some fatty acids are crucial for the normal functioning of our brain, immune system, and even reproductive system. However, these cannot be synthesized by the human body and must be obtained from the diet. Supplementing our intake of these polyunsaturated fatty acid molecules contributes to our health and longevity. Third, fat is fundamental for children's development. The brain requires eight nutrients-protein, fat, carbohydrates, vitamin A, vitamin B, vitamin C, vitamin E, and calcium. In order of importance, fat ranks first, while protein, which we might expect to be near the top, only ranks fifth. Fat should provide 25% to 30% of the energy in the diets of adults and older children, but breast milk provides up to 50% of the energy from fat. This is because infants need more fat for brain and intellectual development. A lack of fat can also lead to stunted growth and development in children, weakened immunity, and increased susceptibility to infectious diseases. Fourth, fat is an important substance for promoting healthy skin. A lack of fat can lead to dry skin, eczema, and slow wound healing. Fifth, fat is also essential for visual development; a deficiency in essential fatty acids can affect vision. Sixth, sexual development requires fat. Research has found that female infants carry genes that control sex from birth. These genes need to reach a certain level of body fat storage before puberty to transmit their genetic code to the brain, producing sex hormones and promoting menarche and ovarian function. Menarche will not occur when body fat content is less than 17%; only when body fat content is greater than 22% can normal ovulation, menstruation, conception, and lactation be maintained. Seventh, fat assists in the absorption of fat-soluble vitamins. Some very important vitamins are fat-soluble and require dietary fat for absorption, such as vitamins A, D, E, and K. Because fat is insoluble in water, cells can store fat without simultaneously storing large amounts of water. The same weight of fat releases more energy than glucose when broken down, meaning storing fat is better than storing glucose. This is one reason why some endurance athletes increase their body fat percentage. If you were to replace body fat with glucose while keeping total energy stores constant, your weight would likely at least double, depending on your level of obesity. Due to the immense benefits of fat as a high-energy fuel, our ancestors evolved these unique fat cells and adipose tissue, thus sowing the seeds of our obesity.