Adipocytes, also called adipose cells or fat cells, are cells that specialize in storing energy as fat in fat droplets. There are two main types: white adipocytes and brown adipocytes.
These contain one large fat droplet and are responsible for storing fat.
These contain many little fat droplets and several mitochondria, which are components of your cells that produce energy which helps maintain your body temperature.
The fat in brown adipocytes is burned to give high amounts of heat energy for hibernating animals. It also provides heat energy to infants who typically need more heat protection. Brown adipocytes get their colour from the large amount of mitochondria, which are brown in colour.
The function of adipocytes is to store energy from unused dietary fat, carbohydrates and proteins, as triglycerides. They excrete these triglycerides if your body needs to utilize its fat reserves.
Adipocytes also secrete the hormones resistin and leptin.
Resistin is a hormone that makes your cells less sensitive to insulin, leading to poor glucose control. As a result, resistin is linked to type 2 diabetes.
Leptin is a hormone that regulates appetite by providing satiety signals, which cause you to stop eating. Leptin optimizes your reproductive cycle and helps control your weight.
Adipocytes also allow your body to adapt to your surrounding air temperature.
When we gain weight, the adipocytes first increase in volume, before increasing in number. When you lose weight, the number of adipocytes do not decrease. You only reduce the size of the adipocytes. As a result, it makes it easier for us to regain weight.
When you use a lot of energy, (e.g., during exercise) or when you have an inadequate intake (e.g., during fasting), adipocytes secrete fatty acids, which are substances that the muscles and other tissues can use as energy. The fatty acids generated by brown adipocytes are usually not secreted. Instead, they are used to produce heat in hibernating animals and infants.
Adipocytes also make and secrete prostaglandins, which are substances that have hormone-like actions. Prostaglandins prevent the breakdown of fat and inhibit the action of leptin. Adipocytes also secrete cholesterol and vitamin A.
Did you know that the amount of fat in your adipocytes can have a big effect on your health? Not enough fat leads to decreased fertility. Too much fat can cause obesity, heart disease, cancer and diabetes.