This is how fat in the body is broken down and rebuilt into chylomicrons, which enter the bloodstream by way of the lymphatic system.

Chylomicrons do not last long in the bloodstream only about eight minutes because enzymes called lipoprotein lipases break the fats into fatty acids.
Lipoprotein lipases are found in the walls of blood vessels in fat tissue, muscle tissue and heart muscle.

Insulin

When you eat a candy bar or a meal, the presence of glucose, amino acids or fatty acids in the intestine stimulates the pancreas to secrete a hormone called insulin.
Insulin acts on many cells in your body, especially those in the liver, muscle and fat tissue.

Insulin tells the cells to do the following:

Absorb glucose, fatty acids and amino acids stop breaking down glucose, fatty acids and amino acids; glycogen into glucose; fats into fatty acids and glycerol; and proteins into amino acids
Start building glycogen from glucose; fats (triglycerides) from glycerol and fatty acids; and proteins from amino acids.

Breaking Down Fat

When you are not eating, your body is not absorbing food. If your body is not absorbing food, there is little insulin in the blood.
However, your body is always using energy; and if you’re not absorbing food, this energy must come from internal stores of complex carbohydrates, fats and proteins.

Under these conditions, various organs in your body secrete hormones:

pancreas – glucagon
pituitary gland – growth hormone
pituitary gland – ACTH (adrenocorticotropic hormone)
adrenal gland – epinephrine (adrenaline)
thyroid gland – thyroid hormone
These hormones act on cells of the liver, muscle and fat tissue, and have the opposite effects of insulin.
When you are not eating, or you are exercising, your body must draw on its internal energy stores. Your body’s prime source of energy is glucose. In fact, some cells in your body, such as brain cells, can get energy only from glucose.

Losing Weight and Losing Fat

Your weight is determined by the rate at which you store energy from the food that you eat, and the rate at which you use that energy.
Remember that as your body breaks down fat, the number of fat cells remains the same; each fat cell simply gets smaller.

Most experts agree that the way to maintain a healthy weight is:

*Eat a balanced diet – appropriate amounts of carbohydrates, fat and protein do not eat excessively – for most people, a diet of 1,500 to 2,000 calories a day is sufficient to maintain a healthy weight
*Exercise regularly

By Craig Freudenrich Ph,D