Can a person eat unlimited calories, and still lose weight, as long as they severely restrict carbohydrates?
No, they cannot. The basis of ketogenic diets, such as the Atkins Diet, is a severe restriction of carbohydrate calories, which simply causes a net reduction in total calories. Since carbohydrate calories are limited, intake of fat usually increases. This high fat diet causes ketosis (increased blood ketones from fat breakdown) which suppresses hunger, and thus contributes to caloric restriction.
Low carbohydrate diets are also characterised by initial rapid weight loss, primarily due to excessive water loss. A decreased carbohydrate intake causes liver and muscle glycogen (glucose) depletion, which causes larger water losses, due to the fact that about three parts of water are stored with every one part of glycogen. Also, restricting your carbohydrate intake reduces the kidney's ability to concentrate urine, leading to an increased excretion of sodium. These entire factors combine, to cause a powerful, but very brief diuresis (increased secretion of urine by the kidneys).
Dieters value this rapid initial weight loss and assume it represents fat loss. The truth is that their body fat stores are virtually untouched, and, as the body adjusts for the water deficit, the weight loss slows down or stops completely. This is when the dieting person usually becomes very frustrated and abandons their diet. Individuals, who do persevere, may lose weight, but only due to the simple calorific restriction mentioned above.
A ketogenic diet often has significant side effects, depending on the individual person. It is certainly much riskier for overweight people with medical problems (heart and kidney disorders, hypertension and diabetes) than it is for overweight people with no health problems. Complications associated with low carbohydrate, high protein diets include ketosis, dehydration, electrolyte loss, calcium depletion, weakness (due to inadequate dietary carbohydrate), nausea (due to ketosis), and very possibly kidney/renal problems. Vitamin and mineral deficiencies are other problems in such unbalanced crash diet regimes. Even Dr. Atkins, the author of both old and new versions of ‘Diet Revolution’ admits that his diet does not supply enough vitamin and minerals and very strongly recommends that people need to take supplements!
Gout is yet another potential side effect, since the uric acid in the blood increases as the uric acid competes with ketones for excretion. This higher blood uric acid level can also increase the risk of kidney failure. Dr. Atkins does warn people with kidney problems that they shouldn't follow his diet, but he completely fails to mention that the diet guidelines themselves might actually produce these disorders!
In the book ‘The Ketogenic Diet’ the author Lyle McDonald notes that the production of ketones from alcohol tends to result in less fat loss, since less free fatty acids are converted to ketones. He also indicates that there is no reason that small amounts of alcohol cannot be consumed during a ketogenic diet, although alcohol consumption slows fat loss. He does however, caution that alcohol may have a greater effect (in terms of intoxication) when someone is in ketosis, but always remember, that alcohol decreases your ability to metabolise fat by approximately 33%!
Finally, the risk of coronary heart disease will be higher in susceptible people who stay on this form of diet for a long time, due to increased consumption of foods high in saturated fat and cholesterol and the obvious consequences.
In conclusion, ketogenic diets such as the ‘Atkins' program are no more successful than those approaches pursued through intelligent nutrition and structured exercise. They are more dangerous than other “fad” weight regimes due to the high fat content involved. Persons who choose to follow ketogenic diets should check with their doctor periodically, as the diet can cause electrolyte depletion (magnesium and potassium) and increased blood lipids (fats). They should have periodic blood tests to measure total cholesterol, LDL (bad cholesterol), HDL (good cholesterol), and triglycerides (the form in which fat is stored in the body).
