Intermittent fasting and life

The BBC showed a Horizon program recently in which it extolled the benefits of the so-called 5:2 diet, the on-off, alternating fasting diet. Apparently, scientists are “uncovering evidence that short periods of fasting, if properly controlled, could achieve a number of health benefits”. The show was presented as these often are by TV doctor Michael Mosley and as is often the case, he tested the diet on himself.

BBC News – The power of intermittent fasting.

In the close of an article about the show, Mosley says: “I was closely monitored throughout and found the 5:2 surprisingly easy. I will almost certainly continue doing it, albeit less often. Fasting, like eating, is best done in moderation.”

So, despite apparently being rather convinced, it appears that he’s not actually going to persist with it…

Anyway, that’s not my biggest problem with this kind of TV. One thing that always worries me about these kinds of programs, is that the presenter puts him or herself into the position of experimental subject. I don’t think you can be both experimenter and the experiment yourself in this kind of research. You need lots of people and controls (people who don’t get the intervention) so you can randomize who does and doesn’t take part and see what effect it has. If it’s just you, then there no one to compare your results with.

Moreover, in the Mosley 5:2 example, hasn’t he done lots of exercise and dietary modifications previously for other TV programs? He enthused about a short-burst exercise regime a while back too, although the actual metrics on his health didn’t really show much of an improvement at all. Apparently, on the 5:2 he did lose weight, but how are we to know that’s not down to his previous exercise and dietary regimes?

I have a friend who is trying the 5:2, he’s not lost any weight yet, but thinks it might be a good thing to be doing, which is fine. If he feels healthier because of it and is happy, then perhaps it doesn’t do any harm. If he loses a few pounds in the course of the diet then that’s great too, but he needs to watch out for metabolic bounce back. If he stops the 5:2 he might find his hunger levels have risen from what they were before and he ends up eating more on average than he did. This seems to be an inherent risk in low-calorie or calorie-restricted dieting. That said, there was some evidence published earlier this year that hinted the yo-yo effect of dieting may not be as hazardous as was once thought.

It’s very hard to know about dieting and life expectancy. After all, the final data doesn’t come until you’re dead by which point it’s too late. It seems, however, that over-indulgence and excess calories makes people heavier and being heavier puts extra physical strain on your heart, blood vessels, kidneys etc. Excess sugar can affect the functioning of your pancreas leading to diabetes which then damages your tissues. Fats and cholesterol can form layers of waxy gunk inside your organs and arteries and lead to blockages that increase the risk of heart attack and stroke.

But, there are overweight people who never develop cardiovascular disease or type 2 diabetes, live long and prosper and there are skinny marathon runners who need bypass surgery in middle age and die prematurely.

Despite what the lifestyle magazines and those selling diet and exercise self-help books say, we really don’t know what is truly good and bad for us. It’s not likely to turn out that pounds of lard and plenty of cigarettes will ever prove to be a good thing (although nicotine seems to reduce the risk of Parkinson’s disease). There are even disadvantages to eating a lot of fresh fruit in terms of rotting your teeth and giving you gut rot and indigestion. Dental and gum infection has been linked to heart disease while chronic digestive problems for some people might not only cause discomfort but may turn out to be a risk for esophagal and colon cancer. Who knows? The evidence can swing both ways.

4 thoughts on “Intermittent fasting and life”

  1. A further comment:
    “It’s not likely to turn out that pounds of lard and plenty of cigarettes will ever prove to be a good thing (although nicotine seems to reduce the risk of Parkinson’s disease).”

    Regarding lard, there’s healthy lard and unhealthy lard. Interestingly, due to changes in feed formulations over the years lard is not nearly so healthy as it used to be due to the high polyunsaturated fat content. Here’s comment on the fatty acid profile of the lard used in contemporary rat chow formulations:

    Again, the harm associated with cigarette smoking depends upon diet as evidenced by the Staffan Lindeberg’s Kitava Study.

  2. Well, you can say that…but there are ambiguities in all health research as you have prominently commented here and elsewhere over the years. We can make broad guesses, but the equations are complicated and personal risk is different from lists in epidemiological databases…

  3. “…we really don’t know what is truly good and bad for us.”

    Actually we do know what sorts of foods cause metabolic damage. South African fitness researcher Timothy Noakes summarizes our current understanding of problems associated with industrialized food in these paragraphs:

    “I concluded that the cause of the global epidemic of obesity and diabetes is simple – both conditions occur in those who are genetically carbohydrate-resistant but who persist in eating the high-carbohydrate diet according to the US Dietary Guidelines. This interpretation is not novel – it was the standard teaching in most medical schools in Europe and North America, but disappeared when the fallacious diet/heart hypothesis took hold in the 1970s.

    But if obesity and diabetes are due to the overconsumption specifically of carbohydrates in those who are carbohydrate-resistant, then their prevention and cure require only that those who are the most severely affected eat a high-fat and -protein diet to which carbohydrates contribute less than 60 g per day. Yet as long as these conditions present massive commercial opportunities to the pharmaceutical and food industries, there will be no appetite for such a simple solution. Our sole recourse is to change the behaviours of those at risk, one meal at a time.

    The evidence is tenuous for the related diet/heart hypothesis, which holds that a diet full of ‘artery-clogging saturated fat’ causes an elevation of blood lipid concentrations, thus promoting coronary atherosclerosis and ultimately heart attack. I argue that the evidence is essentially non-existent.

    Opposing this is that coronary heart disease (CHD) is, like obesity and diabetes, an inflammatory disorder caused by abnormal carbohydrate metabolism in those eating a diet low in omega-3 polyunsaturated fats and high in trans fatty acids and omega-6 polyunsaturated fats.”

    What we don’t know with any accuracy is what constitutes optimum nutrient intake for the individual. Due to differences in metabolic and physiological make up, each person’s nutrient needs are difficult to ascertain without considerable experiment. Using lots of people and controls in experimental settings reveals little about individual nutrient needs.

    Intermittent fasting is probably beneficial for people consuming and adequate and appropriate diet and likely harmful for those struggling with weight issues stemming from a deranged appetite.

  4. People who regularly fast once or twice a week, generally enjoy good health and are disease free till the very end. But fasting means going without food from daybreak till stars are seen in the sky. This is my observation of my elders. They also did not indulge in eating binges but ate moderately rest of the week.

Comments are closed.

If you learned something from Sciencebase, enjoyed a song, snap, or the science, please consider leaving a tip to cover costs. The site no longer runs Google ads or similar systems, so your visit is untainted.