Intermittent Fasting Part II- The Health Benefits

Even though life expectancy in the western world increased form 45 to 77 years of age over the 20th century, the increase in healthy life expectancy was much less marked. Naturopathic and osteopathic principles then, are about increasing quality of life rather than just preventing death. As mentioned in part I last week, there is plenty of anecdotal evidence that calorific restriction (CR) via intermittent fasting (IF) or otherwise does indeed promote health and vitality.

In terms of hard data however, research has mainly involved studies on mice, rats and fruit flies rather than on humans. CR has been shown to increase lifespan by 20-60% if commenced in adulthood or childhood respectively. Disease burdens across the spectrum are reduced including: diabetes, kidney disease, atherosclerosis, neurological degeneration and incidence of neoplastic lesions (cancerous growth).

There are several hypothesised pathways to explain these health benefits in animals. The first and most researched is the IGF-1 or insulin growth factor pathway. This hormone inhibits apoptosis (vitally important and necessary ‘programmed’ cell death) and slows the release of powerful steroid hormones such as growth hormone, prolactin and thyroid stimulating hormone. In mice, gene mutations that cause a reduction in IGF have been shown to dramatically increase life expectancy and to almost completely eradicate the incidence of pathologies visible at autopsy.

Another pathway is via direct neuro-endocrine adaptions to CR. There appear to be reductions in the production of anabolic hormones such as testosterone that promote new cell building over repair of existing cells; beneficial reductions in hormones that regulate cellular metabolism such as noradrenalin. Possibly most important of all, increases are seen in hormones such as cortisol alongside reductions pro-inflammatory cytokines and fat cells which suppress inflammation- a key player in many chronic diseases.

Reduced insulin sensitivity is best known in relation to type II diabetes but is increasingly linked to other chronic diseases. CR has been shown to significantly improve this marker.

“Hormesis” is a posh term for a beneficial mechanism which causes low grade manageable stress and by so-doing, improves resistance to a more serious stressor- in this case disease and ageing (remember the increased lifespan in children raised during the Irish potato famine?). CR seems to promote hormesis and so health and lifespan by stimulation of innate survival responses, more effective DNA repair and better defences against oxidative stress (free radical damage to cells) though this data is correlative rather than causative at this point.

What does this all mean?

There is accumulating data in studies of primates which support the above findings though it will be a few years before these long-term studies are completed. Human studies in Japan ( Okinawa), by the calorific restriction society in the US and from the closed ecosystem experiment- Biosphere2 in the 90s- all support the beneficial findings related to CR. In summary, probably through a combination of physiological, metabolic and cellular adaptions, CR via IF will promote:

• better insulin sensitivity and so help curb the growth in diabetes,
• lower inflammation and so make chronic disease much more manageable,
• reduce adiposity and circulating bad cholesterol
• lower incidence of hypertension, heart attack and stroke,
• lower incidence of kidney and neurodegenerative diseases,
• inhibit cancer formation

Conclusion

The BBC put together an excellent Horizon documentary covering a lot of this ground. Find it here:

“http://www.dailymotion.com/video/xvdbtt_eat-fast-live-longer-hd_shortfilms”

Fasting is certainly not for everyone and, at least initially, it isn’t easy. Start slowly, for example by fasting just one day per week and holding onto some habits such as your morning coffee (which can act as a mild appetite suppressant). Realise that your hunger is significantly affected by the habits and routines formed over a lifetime. Substitute drinking water for snacks. Keep busy and sleep more on fast days. Drop me a line if you need any advice and let me know how you get on!

Thanks,

Christian