The most familiar low-carb diets are the Atkins diet, the modified Atkins diet and the ketogenic diet. The primary aim of the Atkins diet is weight loss. The modified Atkins diet and the ketogenic diet are not recommended for weight loss and are normally used to reduce seizures. All three diets consist in restricting the intake of carbohydrates. The Atkins diets allow more protein intake than the ketogenic diet. In all three diets, ketosis, a particular kind of brain metabolism, plays a crucial role in either weight loss or seizure prevention. As with starting any diet or treatment, consult your doctor first.
Ketosis
Ketosis is a state in which the brain uses byproducts from fat metabolism as a fuel rather than glucose, the usual energy source for the brain. For ketosis to occur, the blood sugar content must be significantly lower than normal. This decreases insulin production and increases the production of glucagon, which is required for fat to be burned. When fat is burned, fat stored in fat cells is broken into fatty acids and glycerol. The liver produces ketone bodies as a byproduct. Glycerol and protein can be turned into glucose, but fatty acids cannot. As fatty acids cannot cross the blood-brain barrier, the brain switches to ketone bodies as a source of energy.
Why Ketosis Is Desirable
Ketosis can be a desirable state for many reasons. If the calorie intake is low enough, the body will burn fat to supply energy for the brain. This will result in weight loss. Ketosis can also reduce the frequency and intensity of seizures in some children who do not respond to anti-convulsant drugs, according to researchers at Johns Hopkins Hospital. As reported in the April 2004 issue of "Annals of Neurology," one theory of how this occurs is that ketosis strengthens cell structure and hence makes the cells less likely to go into the overexcited mode that precedes seizures.
When Ketosis Doesn't Occur
There can be many reasons why ketosis doesn't occur even when one follows a low-carb diet like the Atkins diet. If the carbohydrate intake is too high, the brain will get enough fuel from the conversion of carbs into glucose. If protein intake is higher than what is necessary for maintenance, proteins can be turned into glucose for the brain to use. It is also possible to be in ketosis without knowing it. Ketosis does not automatically give rise to weight loss. As pointed out by Mayo Clinic, for weight loss to occur -- even when you are in ketosis, your body has to use more calories than you consume.
Strategies for Switching to Ketosis
There are many strategies you can use to ensure that ketosis happens. First, if you want to ensure weight loss, count calories for a day or two to make sure that your body uses more calories than you eat, as suggested by Mayo Clinic. On average, the calorie intake should be below 2,000 kcal for women and 3,000 kcal for men. Mature age can decrease these numbers, whereas exercising can increase them. Second, cut down on carbohydrates. Third, eat more fat than proteins without exceeding the allowed calorie intake.
References
- The Diet Channel: Atkins Diet: A Comprehensive Analysis, by Kathleen Goodwin, RD
- "Annals of Neurology"; The Ketogenic Diet Increases Mitochondrial Uncoupling Protein Levels and Activity; P.G. Sullivan, et al.; April 2004
- Johns Hopkins Medicine: Modified Atkins Diet Can Cut Epileptic Seizures in Adults
- Mayo Clinic: Atkins Diet: What's Behind the Claims?
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