Brown fat and its advantages over white fat-
Basically, the humans and mammals have two types of fat namely white fat (white adipose tissue) and brown fat (brown adipose tissue). Brown fat is found abundantly in infants and hibernating mammals. In a new born, it forms approximately 5% of the body mass. It is more in women 7.5% and less in men 3.1% of the body mass. Brown fat is found in people who are least obese. The percentage of brown fat a person has depends on his or her genetic make-up.
In contrast to white fat cells which contain a single lipid droplet, the brown fat cells contain many lipid droplets and a higher number of mitochondria, which offer them a brown color. Mitochondria are the store houses of energy. Brown fat has more capillaries than white fat because of its higher oxygen consumption.
As the infant grows up, the brown fat gradually becomes similar to white fat in function and appearance due to the disappearance of mitochondria found abundantly in them. Since brown fat produces more heat, it has special significance in infants and hibernating mammals because they need more heat to avoid hypothermia.
It has been found that the brown fat cells and the muscle cells are derived from the same stem cells in the embryo. Both muscle and brown fat cells have the same muscle factor-Myf5, whereas white fat cells don’t have it. However, there are two types of brown fat cells- with Myf5 and without Myf5. The brown fat cells without Myf5 have the same origin as white fat cells.
Brown fat cells may actually make one thin. It is also activated when an individual is subjected to cold. It increases the metabolism of the body during cold conditions, which will keep the body warm. It is found around organs with high metabolic activity like adrenals, liver and kidneys. Brown fat keeps these organs at proper temperature so that they function efficiently. The following are the causes of low activity of brown fat cells-
- Low thyroid and adrenal activity will inhibit brown cell activity. The conditions like hypothyroidism will lower its activity.
- Stress which is ubiquitously present in our life reduces the activity of brown fat cells.
- Under-eating and over-eating can also inhibit the activity of brown fat cells. Yo-yo dieting or under-eating in order to reduce fat will fail to bring results.
- High sugar diets will inhibit its activity whereby leading to over-weight and obesity.
- Consumption of bad fats like saturated and trans fats will reduce its activity. One should take right fats and focus on the intake of omega-3 fatty acids, which are important for brown fat activity.
Exercise and brown fat cells-
It has been found that after regular and consistent exercise a hormone irisin is produced in the muscles, which enters the blood stream, to turn white fat into brown fat after a cascade of biochemical events. It may be that irisin and exercise partially determine how much brown fat we have. Irisin appears to have a critical effect on the metabolism. It is worth remembering that exercise increases irisin level in healthy people thus promoting the activity of brown fat cells. How much exercise will activate brown fat cells varies from person to person. The connection between exercise and the role of hormone irsin in activation of brown fat entails more investigation.