Religions have advocated fasting for centuries. A caloric restriction protocol was tested on rats in the early 1930s. The study showed that rats put on a severe diet early in their lives lived much longer than rats raised normally. They were also less likely to develop diseases common in older rats that ate a normal diet.
Recent studies on rats confirm the results of the earlier caloric restriction diets. These studies included intermittent fasting – feeding the rats nothing every other day. The rats on intermittent fasting were found to have better health compared to their counterparts fed daily. The intermittent fasting appeared to protect the rats against stroke damage and cognitive damage – two diseases other rats, in the control group, gained as they approached the end of their lives.
The scientists speculated that intermittent fasting actually provided the rats with levels of cellular defense against molecular damage. The rats were found to have higher levels of BDNF (brain-derived neurotrophic factor). BDNF prevents stressed neurons in the brain from dying. People with low levels of BDNF typically have been found to have diseases ranging from Alzheimer’s to depression. They also discovered rats on an intermittent fast had more responsiveness to insulin. Rats fed a normal diet developed insulin resistance in their later lives. That same insulin sensitivity is seen in humans as they age.
Human studies show similar results as those obtained on animals. A recent study in Spain compared two groups of elderly men and women. One group was put on a normal diet and the other on an intermittent diet of fasting on alternate days for three years. During the three-year program, the normal group spent 219 days in an infirmary tending to various health issues developed during the study. Thirteen people in this group died during the three-year period. The intermittent fasting group cumulatively had only 123 days spent in an infirmary and only six people who died.
Our current tradition of eating three meals a day is significantly different than the eating practices of our ancient ancestors. Some scientists believe that we are genetically predisposed to fast periodically – our bodies and brains work better when subject to intermittent fasting. Intermittent fasting more closely represents the eating practices of our ancestors. They cycled through phases of feast and starvation.