Intermittent fasting has been practised throughout history. Individuals of the hunter-gatherer era faced long periods of time going without food or with very little food to later organise feasts in times of abundance. People from a less distant past had had to face scarcity of food as well. Several modern lifestyles, including some religions, also incorporate fasting in the schedule on alternate days. Is the human body tuned to living without food at certain levels?
Restricting the intake of calories has been deemed as beneficial. For instance, Rhesus monkeys were shown to live much longer when they consumed only 70 % of their normal calorie intake. Furthermore, they were healthier even in old age. Animals that were made to go through intermittent fasting (fasting some days and eating normally on others) also displayed these benefits. Humans fasting alternately were also found to be protected.
Why does intermittent fasting fight ageing though? A team of research students set out to answer this question, with particular focus on the resilience of cells to damage.
Cells are often damaged by free radicals which are sometimes generated by mitochondria that are not functioning well. These are unstable molecules with a loosely-bound electron such that it is easy for them to bind with other molecules, triggering chain reactions that result in the breaking of links between atoms that make up important parts of cells like the membranes and the DNA. Free radicals can be countered by compounds known as antioxidants – the latter absorb the extra unstable electrons and no harmful chain reaction occurs.
Fasting seems to be obstructing the free radicals from damaging cell components. The manner in which they do so is not clear though. One of the plausible explanations entails the replacing of poorly-functioning mitochondria. Fasting decreases the normal glucose levels – a change that is felt by cells. When this happens, the cells use other sources of energy like fatty acids. This process is associated with the removal of unhealthy mitochondria and the adding of healthy ones. The production of free radicals might thus be lowered.
Another explanation might be that fasting itself causes a temporary increase in free radical production such that cells react to this change by increasing the concentrations of natural antioxidants to get rid of the free radicals. Free radicals that are generated like this constitute an effective way of making the body cells respond better with situations of stress.
To investigate how fasting might strengthen cells, the researchers made volunteers practise an intermittent fasting diet for 2 three-week periods; during the first period, the subjects consumed a specially calibrated diet and during the second one, they had that diet with additional doses of Vitamin C and Vitamin E, which are both anti-oxidants.
Furthermore, the participants ate 175 % of their normal daily calorie intake on the days that they did eat so as to ensure that the effects on the cells were those of intermittent fasting and not weight loss. On fasting days, they had 25 % of their normal intake.
Blood samples were taken before and after they ended the diet. The levels of byproducts of oxidative stress and markers of strong cell functioning were monitored.
It was found that the cells made more copies of a gene known as SIRT3 which plays a role in the pathway preventing free radical production and improving cellular repair. Furthermore, circulating insulin levels decreased significantly; it is to be noted that decreased sensitivity to insulin implies a greater risk for diabetes.
Another finding is that the benefits of fasting disappeared when the participants consumed the daily oral vitamin supplements. It seems that the cells then did not increase their natural antioxidant levels, suggesting that low levels of environmental stress from fasting might be good for the body and that antioxidant supplements might sometimes prevent the normal cellular responses.
So, what are you waiting for to include intermittent fasting in your lifestyle?!