Until recently, carbohydrates were ignored as a health issue. They are at least as important, and probably more so, than fats in determining weight and cardiovascular fitness. The key to carbohydrates' influence is insulin. Insulin is a hormone secreted by the pancreas in response to a carbohydrate-heavy meal. It is impossible to live without it, but it is possible to live much better without too much insulin. Insulin has many actions, but some of the most important affect body fat, cholesterol levels, and cardiovascular health. Insulin y facilitates the transport of sugar across cell membranes y promotes conversion of glucose to glycogen and free fatty acids in the liver y promotes storage of free fatty acids as triglycerides (fat) and fat cells y blocks hormone-sensitive lipase (fat-burning enzyme), and y stimulates the production of cholesterol in the liver
The bottom line is that insulin, certainly in excessive amounts, causes the body to produce and store fat as well as produce inordinate amounts of cholesterol.
Insulin is now recognized as an important factor in the development of cardiovascular disease. It is known to act directly on the walls of arteries to produce "atheroma" — atherosclerotic plaques — that can narrow the blood vessels, limit blood flow and oxygen delivery, and result in strokes and heart attacks. Insulin can also cause left ventricular hypertrophy (enlargement of the heart).
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