Can fasting lead to longer life?

Don’t clean your plate – and live longer!

Caloric restriction means taking around 70% of your normal energy requirement, daily for a prolonged period of time. Eat less, live longer… Is it really that simple? When is it too late to start? Can one eat any kind of diet? How long does one continue? How much longer can one possibly live? So many questions pop into the mind… but remain largely unanswered. Much research has been done on yeast, flies, worms, rodents and even on primates to see the effects of energy restriction on lifespan. The results of decades of experiments have generally agreed on one point: fewer calories = longer life.

Fasting rituals are part of many religions and have long professed (anecdotally) many positive effects on health and wellbeing. The very first recorded scientific study on caloric restriction’s direct effect on lifespan was in 1935, by Dr Clive McCay and colleagues (1,2), who concluded that “The object of this study was to determine the effect of retarding growth upon the total length of life and to measure the effects of retarded growth upon the ultimate size of the animal’s body. In the present study growth was retarded by limiting the calories.” More recently, work has focused on the mechanisms (hormones, cellular and mitochondrial changes) and ways to pharmacologically mimic caloric restriction.

Such a spartan approach may be mimicked pharmacologically, and ultimately, drugs merely play with the body’s biochemistry. Long term studies (30 years) in monkeys have given mixed results on whether life extension would really be feasible in humans using this approach. Laboratory conditions are very strict and differ from the real world. Anecdotal studies are not sufficient to prove a hypothesis. Controlled studies are necessary and in case of longevity, one would not know the outcome until a person dies, hence the individuals initiating the study would not be the same ones at the data analysis stage.

Taken with a pinch of salt, for maintenance of health, rather than popping pills and vitamins, we are all aware that mere lifestyle management can do wonders.  Human studies on caloric restriction that looked at indicators of health and disease have noted a greater likelihood of healthier aging in people who restricted calories (3, 4).

So many diseases today are related to lifestyle, and the lessons we learn from historical survey of science and medicine may help us control or prevent illness by our own willpower, knowledge and way of life.


  1. An article honoring 75 years since Clive McCay’s original work on caloric restriction. Ref: J. Nutr. July 2010 vol. 140 no. 7 1205-1210
  2. Dr. McCay and group’s original report from 1935. J. Nutr. July 1, 1935 vol. 10 no. 1 63-79
  3.  In humansJ Gerontol A Biol Sci Med Sci(2015) 70 (9): 1097-1104
  4. Scientific American 2012 article on fasting and longevity


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s