The debate recently reached the pages of the New England Journal of Medicine. (August 21, 1997) Drs. Katan, Grundy and Willett point out that while concerns grew over high fat in the diet, "the perception grew that carbohydrates were innocuous."
First they point out that low fat high carbohydrate diets lower the good HDL cholesterol as well as the bad LDL cholesterol. "Replacement of fat by carbohydrates has not been shown to reduce the risk of coronary heart disease, and benefits are unlikely, because this change similarly lowers HDL and LDL cholesterol, and reduces the intake of vitamin-E and essential fatty acids."
The three doctors also point out that studies of people who are on a fat restricted diet show very little weight loss. In fact, the number of people that are overweight is increasing steadily while the total calories derived from fat is decreasing.
New York complementary medical doctor Robert Atkins was one of the first physicians to champion the cause of the low carbohydrate diet. Atkins believes that obesity is caused by a chronic state of high insulin secretion. High insulin levels cause sugar to be stored as fat and the body becomes less sensitive or resistant to the effects of insulin. This hyperinsulinemia is a major risk factor for both heart disease and diabetes.
Normally in the body there is a balance between two hormones insulin and glucagon. Glucagon causes sugar to be released into the blood stream from fat tissues while insulin removes it from the blood stream and stores it as fat.
New York doctors, Richard and Rachel Heller , authors of The Carbohydrate Addict's Diet , found that excessive carbohydrate consumption leads inevitably to addictive behaviour. A vicious cycle ensues in which high carbohydrate consumption leads to high insulin levels which in turn leads to a drop in blood sugar levels leading to increased cravings for carbohydrates which in turn leads to more carbohydrate consumption and eventually to obesity.
Rachel Heller was massively overweight. After twenty years of agony, ill health and being blamed by her doctor for her failure to lose weight, Heller finally found an effective diet that balances and redistributes carbohydrates throughout the day in order to create a stable constant level of insulin secretion. For two meals a day, you eat no carbohydrates. Then for the third meal, you eat a balanced meal with unrestricted carbohydrates at the same time every day.
Other diet books, such as, The Zone, by PHD researcher Barry Sears promote a diet with low carbohydrates and increased fat and protein. Sears maintains that this diet ensures a steady insulin level and good energy level as well as weight loss.
Sears also emphasizes certain carbohydrates with a low "glycemic index" versus those with a high "glycemic index". Glycemic index refers to the rate at which glucose enters the bloodstream after a carbohydrate is eaten. Examples of low glycemic index foods are rye breads, slow cooking oatmeal, lentils, many vegetables, and yogurt. Examples of high glycemic index foods are sugar, corn chips, rice cakes, puffed cereals of all kinds, cooked carrots, raisins, and white rice.
What does all this mean for the average person? First, if you have consistently failed at every weight loss diet, consider cutting down on carbohydrates. Especially important are sugars and refined and processed carbohydrates. This includes white bread, white pasta, sugar and refined flour products. This may be more important than reducing fat. Eating all carbohydrates at one meal may be another effective strategy.
Dr. Katan and her group advise overweight people to eat less sugar and highly refined starch. They recommend replacing unhealthy fats from meat, dairy and margarine with healthy fats such as olive oil. As for carbohydrates, they should be consumed "mainly in the form of fruits, vegetables, legumes and whole grains."
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