Right from the beginning of time, man has always searched for the key to longevity. Man sought after elixirs of immortality, fountains of youth and even tried to obtain pills or potions of immortality. No matter the time in history, man has always desired to live longer without the complications that come with being old.

Since the mid-1900s and with the help of modern medicine, a lot of research has been put into lots studying various methods to slowing down the aging process and help with longevity. These studies have led to the discovery of numerous nutritional supplements and medications like coenzyme Q10 (which improves mitochondrial function), vitamin C (which reduces oxidative stress and free radicals), Astragalus extract (which upregulates telomerase and increases the length of telomers) and also some special feeding patterns, caloric restriction and fasting, which also play a key role in slowing down the aging process.

Is calorie restriction the same as fasting?

Calorie restriction and fasting though seem similar are two very different things. Calorie restriction is the reduction of the average daily caloric intake by more than 25-50% of what is habitual without the development of malnutrition or deprivation of any essential nutrients. Fasting on the other hand is the complete or severe limitation of food intake for a certain duration of time, either a day, several days, a week or even for as long as a month.

The end product here is not just weight loss but to help longevity by allowing cells to efficiently undergo mitosis, cell regeneration, stability and also by preventing some of the lead causes of death, cardiovascular diseases, cancer and metabolic diseases.

Different forms of calorie restriction and fasting

Forms of calorie restriction:

  • The 5:2 eating pattern: eating is unrestricted for 5 days straight in a week and then 2 days of restricted caloric intake.
  • The 5 day a month pattern: in which one eats no more than 600 calories per day for 5 days while eating is unrestricted for the rest of the month.


  • The time-restricted fasting: a plan in which meals are only consumed within a certain time window and nothing else is consumed at any other time. The 16:8 pattern: This is best method which is in which a person can eat within an 8-hour window and then fast for the remaining 16 hours in a day. One of the easiest ways to follow this plan is to eat early in the evening and then count 16 hours before eating again. The time we are asleep is also included in this 16-hour period.
  • The 1:1 or alternate-day fasting: a feeding plan that is characterized by an alternation between one day with a normal diet and the next day with the complete absence of food intake or extremely minimal calorie intake.
  • Whole day fasting: fasting for a straight 24 hour- period. A common example is when one chooses to eat dinner and then fast till the following day’s dinner.
  • Overnight fasting: this is the simplest and it involves 12-hour fasting every day. It is as simple as eating dinner before 7 pm and breakfast at 7 am.

How does caloric restriction work?

It works by lowering all metabolic activity in the body. This is important because metabolism which includes all chemical reactions taking place in the body to provide energy for vital processes to maintain the living state of the cells and the organism as a whole is not 100 % safe and efficient for the cells because, as oxygen is used in mitochondria to make energy in the form of ATP, reactive oxygen species are produced and their accumulation leads to damage of the cells especially their genetic material which seriously contributes to the aging process.

Thus, by using calorie restriction to slow down the metabolic activity of the cells, we reduce the oxidative damage to cells and improve the metabolic health and extend the lifespan of cells. Calorie restriction also helps with mitochondrial reproduction.

How does fasting work?

In most mammals, fasting results in lower glucose levels which causes the body to switch its main source of energy from glucose to other sources of energy, fats and fat-derived ketone bodies. This, in turn, leads to an increase in insulin sensitivity and better regulation of blood sugar levels, reduction of fat levels which in turn reduces chances of developing metabolic diseases, weight loss and lastly, induction of stress on the cells and as a result, leads to autophagy.

Autophagy is the process of utilization and renewal of necessary parts of old, dying cells, therefore these dying cells can be used as building blocks of new cells. Autophagy in cells is a process that had been discovered over 60 years ago but was only recently was given much focus by a Japanese scientist, Yoshinori Ohsumi, who extensively researched this process and eventually went on the win the Nobel prize in 2016 for his discovery of the sets of genes responsible for the control of this process.

One of the few ways autophagy increases longevity is by reducing the possibility for the development of cancer cells by preventing reactive oxygen damage to the genetic material, reducing the possibility of DNA mutations. Fasting also has the ability to reduce inflammation, increase the removal of apoptotic cells, harmful organelles and help improve hermetic response, a favorable, positive, biological response due to repetitive mild stress.

Benefits of fasting and calorie restriction

Apart from the proven anti-aging effects, fasting and calorie restriction has various other health benefits which include great boosts in cognitive performance, improvement of overall fitness, protection from the development of obesity by reducing triglyceride levels in the body, cardiovascular diseases and metabolic diseases, especially diabetes via the improved regulation of serum glucose and increase in sensitivity to insulin.

Fasting and calorie restriction have also been shown to improve the prognosis of cancer via induction of ketosis, an alternate source of energy that cancer cells cannot efficiently convert to energy.


The health benefits of fasting and calorie restriction are no doubt evident, but a lot more still needs to be learned about their effectiveness and safety, especially in the elderly. If tempted to try one of these diets, talk to your health care provider to be provided with more information about a proper safe level of nutrition during this diet.