BG2: Why fasting is good for you


Many of the changes in my body when I took part in the clinical trial of an intermittent fasting diet were no surprise. Eating very little for five days each month, I lost weight, and I felt hungry. I also felt more alert a lot of the time, though I tired easily. But there were other effects too that were possibly more important.

During each five-day fasting cycle, when I ate about a quarter the average person’s diet, I lost between 2kg and 4kg (4.4-8.8lbs) but before the next cycle came round, 25 days of eating normally had returned me almost to my original weight.

But not all consequences of the diet faded so quickly.

I would like to point out that if you’re heading towards the end of life where you expect things like ?cancer, dementia, diabetes and heart disease to rear their ugly heads, then the 5:2 “diet” is more about the health benefits than the almost incidental weight loss you can achieve. ?

Clinical tests showed that during the diet cycles my systolic blood pressure dropped by about 10%, while the diastolic number remained about the same. For someone who has, at times, had borderline hypertension, this was encouraging. However, after the control period (normal diet), my blood pressure, like my weight, returned to its original – not-so-healthy – state.

The researchers will be looking at whether repeated cycles of the diet could be used to help manage blood pressure in people over the longer term.

Arguably, the most interesting changes were in the levels of a growth hormone known as IGF-1 (insulin-like growth factor). High levels of IGF-1, which is a protein produced by the liver, are believed significantly to increase the risks of colorectal, breast and prostate cancer. Low levels of IGF-1 reduce those risks.

Why does this happen, when all you do, perhaps only once or twice a week, is eat a lot less, while you eat normally for the rest of the time?

My blood tests also detected a significant rise in a type of cell, which may play a role in the regeneration of tissues and organs.

It is a controversial area and not fully understood by scientists.

“Your data corresponds to pre-clinical data that we got from animal models that shows that cycles of fasting could elevate this particular substance, considered to be stem cells,” said Dr Min Wei, the lead investigator.

The substance has also been referred to, clumsily, as “embryonic-like”.

“At least in humans we have a very limited understanding of what they do. In animal studies they are believed to be ’embryonic-like’ meaning… they are the type of cells that have the ability to regenerate almost anything,” says Longo.

In laymans terms, what is hoped is that by shocking the body by fasting, it goes into a ‘self-repair’ cycle that fires off stem-cell like cells that can be used by the body to repair itself. ?In simpler terms: ?you’re healthier and may live longer.

It’s only a very recent phenomenon that people don’t have to skip any meal. ? Our bodies weren’t made for a constant supply of food. ?And when you take it back to how it used to live: sometimes feast, sometimes famine, it does a much better job of looking after itself when it is allowed to run the repair cycle.