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The Surprising Benefits of Short-Term Fasting

We all know about fasting as a religious practice and calorie reduction as a way to lose weight, but short-term fasting is also a way of preventing aging in the brain.

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Robert Rister
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Fasting has been used as a tool of achieving mental and spiritual clarity for millenia. Until recently, however, neurological researchers had not investigated whether short-term fasting, that is fasting for a 12- to 18-hour period, might have all the benefits imputed to the nearly impossible task of calorie restriction for months, years, or even a lifetime.

There is general agreement in the scientific literature that fasting "gives the brain a break" so it can deal with the chemical byproducts generated during stress. Tissue-damaging free radicals of oxygen invariably escape the mitochondrial "furnaces" of brain cells during the process of creating energy from glucose. The less glucose the brain has to process, the fewer free radicals of oxygen available to cause damage to the brain. Fasts as short as 12 hours are enough to allow the brain to rebuild its connections to enhance focus, memory, agility, and sensory perception. Here are the major findings of the research:

  • Sticking to a low-calorie diet over a period of months or years always lowers body weight. fasting for twelve to eighteen hours at a time may or may not lower body weight, but, also surprisingly, it often does. That is because the body does not have a chance to reset its calorie "thermostat" during a short-term fast. Excess calories eaten after a brief fast are burned at body's usual rate. 
  • Long-term calorie restriction reduces body fat. Intermittent fasting also reduces body fat.
  • Long-term calorie restriction lowers body temperature (slowing down the process of oxidation in the brain). Intermittent fasting also lowers body temperature.
  • Long-term calorie restriction lowers blood pressure and slows the heart rate. Intermittent also fasting lowers blood pressure and slows the heart rate to a more nearly athletic level.
  • Long-term calorie restriction lowers blood insulin levels, associated with the depositing of fat. Intermittent fasting also lowers blood insulin levels.
  • Long-term calorie restriction increases HDL (the “good” cholesterol). Intermittent fasting also increases HDL.
  • Long-term calorie restriction decreases homocysteine. Intermittent fasting also decreases homocysteine.
  • In laboratory experiments with animals, long-term calorie restriction produces a 50 percent increase in the brain protective chemical beta-hydroxybutyrate. Intermittent fasting produces a 100 percent increase in beta-hydroxybutyrate.
  • Lowering blood sugar levels by short-term fasting reduces the sensitivity of brain tissue to excitotoxins such as MSG (which stimulates appetite) and Nutrasweet.

Dr. Jose A. Luchsinger of the Columbia Presbyterian Hospitals in New York City and his colleagues studied the association between caloric intake and mental decline in 980 elderly individuals who did not have Alzheimer's at the start of their study. The researchers followed these patients for an average of four years and recorded how many calories they ate. The research team also tested for the presence of the apolipoprotein E (APOE) epsilon 4 allele, a gene that has been associated with Alzheimer's disease.
During the study, 242 patients developed Alzheimer's, and 28 percent tested positive for the APOE epsilon 4 gene. The group that consumed the most calories had a 50 percent greater chance of developing Alzheimer's. Among the 263 patients who tested positive for the APOE epsilon 4 gene, those who consumed the most calories had a 2.3 times greater chance of developing serious mental decline compared to those who ate the fewest calories.
Anyone who has ever tried to stick any kind of low-calorie diet knows that consumption inevitably creeps back up. Fortunately for the prevention of Alzheimer's, an occasional one-meal fast is more effective than sticking to a low-calorie diet. Experiments have found that skipping a meal is helpful even if the lost calories are made up at the next meal. The bottom line of this research is that skipping one meal every day or every other day, or at least replacing one meal every other day with a low-calorie snack, should slow or prevent the onset of Alzheimer's. The research suggests that short-term fasting enhances mental acuity in persons not yet at risk for Alzheimer's, too.  

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External Sources:
Physical activity, diet, and risk of Alzheimer disease.
This Article appears in:
Eating strategies
fasting, weight loss, mental clarity, focus, brain health
 Darin Gregg  
 05 Apr 2012, 08:12
 I am hypotyroid and low adrenal so struggle with temp, and low blood pressure. I started doing 12 hour fast two weeks ago and blood pressure is now really low and temp. in morning only 97F. That's bad isn't it? Maybe fasting shouldn't be done if you are hypothyroid?
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