The Fast Track to Longevity

By Lauren Hoskin

It’s 1pm and my parents are sitting down for their lunchtime mug of vegetable stock, approximately 12 calories. Having being on the fasting diet for over a year, my mum announces smugly that she can now fit into things that she hasn’t worn since her twenties. She couldn’t sound more like a weigh-watchers advert if she tried!

The diet is simple, eat normally for five days of the week and restrict calorific intake to 25% of the required amount on two days. This isn’t simply a faddy weight-loss diet though. Scientists suggest that Calorie Restriction and Alternative Day Fasting can have powerful impacts on longevity. This can help to reduce the risk of many age-related diseases such as cancer, cardiovascular disease, type-2 diabetes and brain atrophy.

During times of feast, the production of Growth Hormone GH stimulates the secretion of a growth factor hormone called IGF-1. IGF-1 promotes cell growth, cell proliferation and new tissue formation whilst also inhibiting cell death. This system is vital when we are young and growing. High levels of IGF-1 once we have reached maturity, however, are linked to accelerated ageing and disease.

Fasting is an effective way to reduce blood levels of IGF-1. This could therefore be allowing cells to enter a reparation state, where repair genes are switched on and old cells can be killed off. Through this mechanism, the risk of cancer could be reduced by increasing cell repair activity and decreasing cell proliferation. Additionally, type-2 diabetes and insulin resistance are reduced as a result of increasing insulin sensitivity.


Numerous studies have shown evidence for these mechanisms in worms, mice and monkeys, but evidence is only anecdotal in humans. In a trial of 76 Rhesus monkeys carried out over 20 years, it was shown that the monkeys on a calorie-restricted diet had less than half the rate of cancer and cardiovascular disease than the monkeys on a non-restricted diet. The calorie-restricted monkeys also had superior preservation of movement, memory and appearance into old age.

Until the arrival of more robust evidence from human trials, the fasting diet will remain open to many sceptics. However, this has not stopped thousands of people from trialling it themselves and benefiting from weight loss.

If reductions in bloodstream IGF-1 levels really do reduce the risk of cancer then this could prove an effective disease prevention technique. Similarly, it is conceivable that this mechanism could work as a complimentary cancer treatment alongside medicinal therapies to slow the growth of tumours.