Fat breakdown, also called lipolysis, occurs mainly in fat cells (adipocytes). The most important function of lipolysis is energy production. However, there are interfering factors that inhibit fat breakdown.
What is fat breakdown?
Fat breakdown, also called lipolysis, occurs mainly in fat cells. The most important function of lipolysis is energy production. Fat breakdown in the body is also called lipolysis. In this process, fat cleavage already begins in the stomach, where, however, only about 15 percent of the fat is broken down into so-called monoacylglycerides. The majority is then converted into monoglycerides in the intestine. Lipases are responsible for fat cleavage. Together with long-chain fatty acids, the monoesters then form so-called micelles. These micelles passively diffuse through the cell membranes into the intestinal mucosa. There, they are converted back into fats and, by binding to cholesterol, phospholipids and lipoproteins, are stored together to form chylomicrons. Chylomicrons are considered the actual transport form of lipids in the blood, which includes fats. They are transported with the blood mainly into the fat cells (adipocytes) and to a small extent also into the muscle cells and the liver. It is in the adipocytes that the actual lipolysis then takes place.
Function and task
Fat breakdown in adipocytes represents the most important source of energy for animals and humans. In evolution, this form of energy storage has proven to be very effective. In times of food abundance, more calories were taken in than consumed, and the excess energy was then stored as fat in adipose tissue. In times of food shortage, the body could then draw on these reserves. Today, because there is a constant abundance of food in industrialized countries, fat gain outstrips fat loss for many people. The result is increased storage of body fat. Adipocytes are increasingly enriched with fats. Nevertheless, a constant fat breakdown takes place in the adipose tissue, because even a strongly filled adipose tissue must constantly supply the body with energy. It is just that when energy requirements are lower, lipolysis is not sufficient to establish a balance with lipogenesis (fatty acid synthesis). Lipolysis in adipose tissue occurs in three steps. First, the enzyme adipocyte triglyceride lipase (ATGL) cleaves a fatty acid, leaving a diglyceride. In a second step, this diglyceride again undergoes fatty acid cleavage by hormone-sensitive lipase (HSL). The resulting monoglyceride is now cleaved by monoglyceride lipase (MGL) into a fatty acid molecule and glycerol. Fatty acids and glycerol molecules are transported via the blood to their target organs, where they are converted into simpler compounds, such as carbon dioxide, water and ketone bodies, while generating energy. Fat breakdown in adipocytes is controlled by hormones. Certain hormones, such as adrenaline, noradrenaline, glucagon, ACTH, cortisol, growth hormone and thyroid hormones, activate lipolysis. Other hormones, however, inhibit fat breakdown. These include insulin and prostaglandin E1. Nicotinic acid and beta receptor blockers also have an inhibitory effect on lipolysis. The hormonal regulatory mechanisms for fat breakdown are derived from the nutritional status of the organism.
Diseases and disorders
The disturbed balance of fat build-up to fat breakdown takes on pathological features in industrialized countries today. Obesity (obesity) has now become a widespread disease. Obesity can lead to many degenerative diseases. First, there is a significant increase in type II diabetes. As part of the metabolic syndrome, arteriosclerosis, lipid metabolism disorders and cardiovascular diseases can develop in addition to diabetes. In addition, the number of diseases such as arthritis, arthrosis or rheumatism is also increasing. A link between obesity and certain cancers has also been established. Of course, it has long been known that reducing excess fat can reverse many diseases. For example, type II diabetes can be stopped in the early stages by reducing fat through a change in diet and plenty of exercise. Diseases of the cardiovascular system also have more positive prognoses when excess weight is reduced. The main prerequisite for a healthier life is therefore the reduction of excess weight through a change in lifestyle.However, sometimes this path is not so simple. For example, there are also diseases and physical imbalances that stand in the way of a normal reduction of body fat. If the thyroid gland is underactive, losing weight becomes very difficult because there is insufficient thyroid hormone to activate the metabolism. As a result, the basal metabolic rate is greatly reduced. The body consumes too little energy. Other hormone disorders can also inhibit fat loss. For example, cortisol activates lipolysis. However, it also increases the breakdown of the body’s own proteins into glucose, which is then converted into fat. In addition, muscle breakdown also leads to a decrease in basal metabolic rate. As a result, truncal obesity with characteristic fat distribution develops. Lipogenesis is also promoted and lipolysis inhibited in cases of testosterone deficiency or excessively high estrogen levels. Furthermore, food allergies have been found to release substances that impede fat breakdown due to sustained inflammatory reactions. In recent years, the dependence of body weight on intestinal flora has also been recognized. Thus, overweight people have intestinal flora that is likely to produce substances that inhibit fat loss. Certain medications can also make weight loss more difficult. These medications include blood sugar and cholesterol-lowering drugs, beta-blockers, cortisol-containing drugs, antidepressants, neuroleptics, or the pill. Flavor enhancers, such as glutamate, can paralyze the feeling of fullness. Furthermore, it has been found that sweeteners can trigger cravings. So, on the one hand, fat loss has a great effect on physical health, and on the other hand, it is activated or inhibited by various factors.
