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Calorie Restricting for Longer Life

A few months ago, I watched a BBC Horizon documentary on the effects of calorie restricting and how it affects the body's aging process and I was intrigued to say the least.

I watched it again a few nights ago just to remind me and press home the importance of the message it was getting across. Here's my own take on what I learned from this.

The documentary explored the way in which restricting the calorie intake of mice resulted in greater longevity compared to mice that ate normally and resulted in reduced life span of those that were fed a high calorie diet.

So far so good. These kinds of tests have been running for decades.

Restricting Calories

voluntary calorie restrictionWhat I didn't know was that there is a pretty big group in the United States that deliberately calorie restrict on a daily basis. A comparison set of tests done by the Horizon presenter, Michael Mosley with a man of similar age and build revealed that while they looked similar on the outside, it was a very different story on the inside.

The physical age of the guy who had been calorie restricting for over 10 years had the internal layout of a 20 year old!

There were many more huge differences such as fitness, stamina and balance with physical/mental differences such as reaction times, motor skills etc. This guy was so healthy he had no need of any medication and the doctor carrying out the tests said that he would be unlikely to need them even going into old age.

I was particularly interested in the mental side of these tests, as it seems that restricting calorie intake can positively affect mental ability and reduce the risk of age related mental illness such as Parkinson's and Alzheimer's. After all, if this kind of lifestyle can mean living longer, I'd want to get old with my mind in as healthy a state as my body!

Cell Life

But there appear to be well understood reasons for this increase in physical and mental health as well as life expectancy. It all comes down to not necessarily what a person's genes say, but in how their DNA "ages".

Scientists now know that at the end of each strand of DNA is a "tail" known as a "telomere" and these are there to protect the DNA from damage. It is also known that as cells divide and reproduce, the length of the telomeres shortens slightly.

The more times the cells divide, the shorter the telomeres get, leading to an indicator of how a person is aging. You can read more about this fascinating branch of science here: Are Teleomeres the Key to Aging and Cancer?

We also know that when we feed ourselves normally (as we perceive it), our bodies are in GO-GO mode, constantly replacing damaged and aging cells with new healthy cells.

We can make that process go even faster by working out and eating a high protein diet to force the production of new muscle cells. We do that in order to build bigger and stronger muscles as any bodybuilder or athlete knows.


This process is determined in our bodies by the levels of a growth hormone called Insuline-like Growth Factor 1 (IGF-1). The more of this stuff our bodies secretes, the faster we build new cells to replace old ones. Up until I saw this documentary, I probably like most people, regarded this process as a good thing.

I appear to have been wrong!

The obvious putting of two and two here is that by accelerating the speed at which cells reproduce, we are speeding up the shortening of telomeres and that means speeding up the race towards the end of life! It also increases the risks of cancer cells growing faster as well as causing faster aging of the body.

The documentary focused a lot on how we can reduce our levels of IGF-1 and thereby literally slow down the aging process. This would happen because it would slow down the cell reproduction rate.

Better still, instead of cells dividing and new cells being produced to replace old or damaged cells, they instead go into "repair mode" and repair themselves instead of self destructing to make way for new cells.

"As levels of the IGF-1 hormone drop, a number of repair genes appear to get switched on according to ongoing research by Professor Valter Longo of the University of Southern California."

Eating and Fasting

The way to do this is to restrict the intake of calories daily. Goes back to where this article began, where we can literally prolong our normal life expectancy by choosing what we eat and drink. But there's more...

If the idea of severely restricting your calorie intake every day doesn't sound very appealing, you can get what is believed to be an even more profound effect by regular fasting. This means going for long periods without eating anything and just drinking water.

In many cultures, fasting on a particular day of the week is quite common. But there is fasting and there is fasting. The Horizon documentary covered several forms.

Michael Mosley had his IGF-1 levels checked via a blood test and found them to be relatively high. He then underwent a three day fast, at the end of which a further blood test showed his IGF-1 levels had halved. Unfortunately, the effects are not long lasting and regular fasts would be necessary to sustain the lower and safer levels of IFG-1.

He tried other kinds of fasting.

Alternate Day Fasting

Alternate Day fasting (ADF) is a more civilized way of restricting calorie intake, whereby you eat normally one day, and restrict calorie intake (600 for men and 500 for women) the next. The results of tests carried out by Dr Krista Varady of the University of Illinois at Chicago over an eight week period are consistent with reducing IGF-1 to desirable levels. She said,

"If you were sticking to your fast days, then in terms of cardiovascular disease risk, it didn't seem to matter if you were eating a high-fat or low-fat diet on your feed (non-fast) days."

Another form of this kind of fasting is the 5:2 Diet, where you eat normally for five days in the week and calorie restrict the other two. Mosley placed himself on this version and after several months reported low levels of IGF-1 and naturally some weight loss (14 pounds) along with reductions in blood cholesterol, glucose and triglyceride levels and a similar increase in health.

What Does it All Mean?

happy eatingIf you're reading this and wondering what the implications could be for you should you decide to try reducing your weekly calorie intake, prepare to be amazed. I was so interested that I tried my own experiment, fasting one day a week but also reducing my calorie intake on normal days to 2,500 max, although I often stayed well below that.

I did this for a month, after which I got a blood test and y IGF-1 levels are now low, with cholesterol, triglyceride and glucose blood readings that pleased my doctor! I also lost around 10 pounds in weight. I continue with this routine although not quite so strictly and to date have not gained any weight.

My exercise levels are unchanged, with about an hour a day dog walking. I always take the stairs when I encounter them and feel more energetic than I have done in years. I don't know if this will result in longer life expectancy, but I do hope that I keep my health for as long as possible this way. That alone makes it worth doing.

I'm not sure too many people will be willing to participate in anything similar, because eating the way we do in the West has become so ingrained in our culture that it will be tough to change it. Giving up the hamburgers, fries, red meat, dairy, white bread, cakes, cookies, candy, soda and all those other nice things can be pretty tough if you're used to having them all the time.

I found it fairly easy, as I already eat a predominantly Mediterranean diet because of where I live (on the Mediterranean coast!) and do not eat anything processed or out of a packet or can. That means my sugar intake is very low (see my last post). I don't drink any soda or other flavored drinks, almost no dairy or red meat, so yeah, it was an easy transition.

The implications of this information are huge. It appears that we can, by adjusting what we eat, how much and when we eat it can seriously prolong our lives and improve our health. Who wouldn't want that? You can read about the BBC Horizon documentary here: The power of intermittent fasting.

- Terry Didcott


Posted on Sat, 08 Dec 2012 in Diet | 0 Comments

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