29/03/2025
1. Fat Storage and Removal
When the body absorbs dietary fat, it is broken down into fatty acids and glycerol during digestion. These components enter the bloodstream and are transported throughout the body. Excess fatty acids are synthesized into triglycerides in the liver and fat cells, where they are stored. When we consume more calories than needed, the body stores excess fat in adipose tissue for future energy demands.
Storage: When food is consumed, dietary fats are digested in the intestines, and fatty acids and glycerol enter the bloodstream. They are then transported to adipose tissue, where they are converted into triglycerides and stored in fat cells. This process is regulated by hormones such as insulin, which promotes the uptake and storage of fatty acids and glycerol into triglycerides.
Catabolism (Breakdown): When the body requires energy, stored fat is mobilized, such as during exercise or fasting. Hormones like adrenaline and norepinephrine activate lipase enzymes in fat cells, initiating the breakdown of triglycerides into fatty acids and glycerol for energy use.
2. Fatty Acid Release and Transport
Once broken down, fatty acids are transported via the bloodstream to the liver, muscles, and other tissues that utilize them as an energy source. Fatty acids are carried by plasma proteins such as fatty acid-binding proteins (FABPs) and albumin to where they are needed for energy restoration.
Muscles: During physical activity, muscle cells have a high demand for energy. Especially in aerobic exercise, fat becomes a key energy source. Fatty acids enter muscle cells and undergo beta-oxidation in mitochondria, breaking down into carbon dioxide and water while generating ATP (the cell’s energy currency).
Liver: Fatty acids also enter the liver, where they undergo oxidation and are converted into ketones, which serve as an alternative energy source for the brain and other tissues—especially during prolonged fasting or low-carb diets like the ketogenic diet.
3. Beta-Oxidation (Fatty Acid Oxidation Process)
Inside cells, fatty acids enter the mitochondria and undergo oxidation, the primary metabolic process for fat breakdown. During each oxidation cycle, two carbon atoms are removed, forming acetyl-CoA. These acetyl-CoA molecules enter the citric acid cycle (also known as the Krebs cycle), ultimately producing ATP through the respiratory chain. This process is the core step in the body’s fat energy supply.
4. Ketone Production and Utilization
During prolonged fasting or low carbohydrate intake, the liver converts fatty acids into ketone bodies. Ketones—including acetoacetate, beta-hydroxybutyrate, and acetone—are highly efficient energy sources, particularly for the brain. Normally, the brain relies primarily on glucose, but in times of fasting, it can use ketones as an alternative energy source.
5. Regulation of Fat Metabolism
Fat metabolism is regulated by various hormones and enzymes. Key regulators include:
Insulin: The most important hormone for fat storage, insulin levels rise when blood sugar is high, promoting fat storage. Insulin inhibits lipolysis (fat breakdown) and encourages energy storage in fat cells.
Adrenaline and Norepinephrine: Released in response to stress, exercise, or fasting, these hormones stimulate fat breakdown and the release of fatty acids into the bloodstream.
Growth Hormone: Important for childhood growth, it also aids in fat loss and the release of fatty acids.
Testosterone and Estrogen: These s*x hormones influence fat distribution and metabolism. Testosterone promotes fat loss, whereas estrogen encourages fat storage in areas like the thighs and hips.