All diets have one thing in common: They work only if your daily intake of calories is lower than the calories used by your body during the day. Any state of weight loss resembles starvation by depriving the body of the calories it needs. Some severe diets, however, produce a chemical state that is very similar to the chemical state of fasting, or starvation in circumstances such as famine.
Stages of Starvation
When the body goes from a normal, healthy state to a mode of starvation, it first uses the glucose already in the blood. Once your blood sugar has decreased sufficiently, glucose stored as glycogen in the liver is converted back into glucose. When glycogen levels drop too low, your body's only choices are to turn to either protein or fat consumption. Because proteins are the main constituents of vital organs such as the heart, the body's first choice is to metabolize stored fat and protect your vital organs.
Ketosis
Fat is converted into fatty acids and glycerol during fat metabolism in the liver. The liver also produces ketone bodies as biproducts of fat metabolism. Glycerol can be converted into glucose, but the human body does not have a way to convert fatty acids into glucose. Your muscles can use the fatty acids floating in the bloodstream as energy, but your brain cannot. This is because the fatty acids cannot pass from the blood into the brain. When there is a shortage of glucose, which is the brain's preferred energy source, the brain begins to metabolize the ketone bodies in a process called ketosis.
Diets Imitating Starvation
Some diets aim to produce a state that chemically resembles that of starvation. Starvation diets severely restricts calories. The most severe are water fasting diets. The less severe diets allow for some food consumption, for example, one small meal a day. When calories are severely restricted, your body reacts the same way it would during involuntary starvation. Low-carb diets also seek to induce a starvation mode. The most well-known low-carb programs include the Atkins diet. When Atkins diet works, it restricts calories along with carbohydrates. This approach also sends the body into a starvation mode and causes ketosis.
Health Consequences
All kinds of starvation, whether voluntary or not, can seriously harm your body and brain. The harsh consequences of starvation were documented in the Minnesota Starvation Experiment in 1944, as reported in the June 2005 issue of "The Journal of Nutrition." Newer studies have shown that anorexics in a progressed state have reduced gray brain matter as well as organ failure. A study published in the May 2010 issue of "International Journal of Eating Disorders" showed that brain damage caused by starvation in anorexia is reversible. But organ failure may not be. Organ failure occurs when there is a shortage of essential amino acids and essential fatty acids. As the body cannot produce essential nutrients, essential amino acids and essential fatty acids must be provided by food.
References
- Science Daily; New Clues Uncover How 'Starvation Hormone' Works; Dec. 2010
- Drs.Eades.com; Metabolism and Ketosis; Michael R. Eades; May 2007
- American Medical Association; A Critique of Low-Carbohydrate Ketogenic Weight Reduction Regimens: A Review of Dr. Atkins' Diet Revolution; June 1973
- Mayo Clinic: Atkins diet: What's behind the claims?
- Science Daily; Brain Volume Found to Change Following Weight Gain in Adults With Anorexia; May 2010
- The Journal of Nutrition; They Starved So That Others Be Better Fed: Remembering Ancel Keys and the Minnesota Experiment ; Leah M. Kalm and Richard D. Semba; June 2005
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