I have been brought up with an awareness of, and interest in nutrition. However, the more one tries to learn, the more contradictions and paradoxes one gets faced with.
The most fundamental starting point is that not eating enough kills in weeks, and not drinking enough in days. We all have an instinctive sense of this, that keeps us alive, but that instinct can sometimes also lead us astray.
In fact, for the large fraction of the Western World that is enjoying an abundance of food in our time, the threat to health comes more from surfeit than lack. Although we mostly avoid the harm that comes from simple insufficiency of food, many people, including a lot who should know better, eat imbalanced diets that skimp on some key nutrients while overloading their metabolisms with more than they can cope with of others, and ever more of us eat imbalanced diets on such an epic scale that we break our health in the long term. The consequences of excess kill about 200 times more slowly than those of famine, but kill they do, and millions of years of potential life are going unlived as a result.
Given that we all know eating is good, and it is not transparently inconsequent logic to deduce that eating more must therefore be better, why it does not turn out that way in real life is a mystery to laymen and a challenge to scientists. The crudest measure of overeating is obesity. Being a simple thing to grasp, much money can be made from encouraging the insecure to fret about this, and there is an undeniable correlation between obesity and ill-health. However, scientific research shows that it is not a simple causal relationship: The minority of fat people, who keep their muscles fit beneath the blubber, have the same mortality rate as the lean and fit, and rather better than the merely weedy, according to the epidemiologists. Other studies have made it plain that where the fat lies is more of an indicator of problems than how much there is of it. Be it cause or, more likely, co-consequence, substantial abdominal fat goes hand-in-hand with the excessive levels of various chemicals in the blood that wreak the real damage, unseen and unfelt; whereas subcutaneous fat is a far greater menace to vanity than to health.
Chemicals in the blood, wreaking unseen and unfelt damage. There, I think, I have reached the crux of the matter; how we harm ourselves with our food without triggering any protective instincts. Only in our time have medical scientists worked out the significance of some of the many ingredients to be found in our blood, and they are still unrolling the story – below I shall come to explain how this article was sparked by learning of some current research. Everything every cell in the body needs to consume or dispose of must get into the bloodstream, but there are lower and upper limits to what is useful and harmful.
Sugars are one of the best known levels to need controlling. Without energy to live by, we are not viable organisms, but overfeeding individual cells can have dire consequences for the body as a whole. Perhaps one of the best-known of our hormones, insulin, regulates blood sugar, as one of the most important of its multiple functions, but constantly sending vast quantities of sugars from our guts to our blood can overwhelm the insulin process with at least two dire potential consequences: syndrome X, where persistently elevated insulin levels create resistance to all its metabolic effects throughout the body, with similar results to premature aging, and type 2 diabetes, where the body's ability to produce enough insulin simply burns out, with much the same effect as syndrome X and more besides, including life-threatening harm to circulation and brain function amongst other symptoms.
Cholesterol levels are another that most people know are a risk area. I myself am under doctor's advice to restrict saturated fat intake, after a couple of poor results for Low-Density Cholesterol level tests. Letting LD cholesterol get out of hand leads to the surplus precipitating out in blood vessels, until a stroke or heart attack cuts you off in your prime. An even more dismal prospect than eating less cheese and sausage!
Much more recently than the discovery of insulin, scientists have begun to investigate the role of a related hormone to insulin itself, to which they have given the distinctly uncatchy name of insulin-like growth factor 1, or IGF-1 for short. The root of this article is in a BBC2 Horizon programme, which included some coverage of research into the causes and effects of varying IGF-1 levels. It seems that adult humans metabolise digested proteins over a two day cycle, with a corresponding rise and fall in IGF-1 levels, and differing responses to rising and falling levels. In particular, according to the research featured in the programme, falling IGF-1 levels are the cue for the body's healing and immunity processes. Another question that the same programme gave some attention to was the very controversial idea of Caloric Restriction as a healthy approach to eating.
For some years I have been aware that some study has been done on comparing laboratory animals on varying degrees of restricted diet with others allowed to feed ad lib. These studies invariably achieve substantial longevity gains for the half-starved subjects. Curiously, though, humans who eat limited diets, from either poverty or spiritually motivated asceticism, do not often seem to live especially long lives. However, some of the best life expectancy statistics do come from places with a cultural tradition of eating nutritious but energy-poor staples, so there may be something in it. When reading of the latest research on Caloric Restriction, I always suspected that the likely mechanism was that reduced energy availability enforced more rest on the test creatures. However, the IGF-1 research, in which the low blood levels a day or more after a rich, high-protein high energy meal has been fully metabolised were linked to a boost in immune function and healing processes, while the high levels immediately after suppressed it, offers a realistic explanation for how animals kept permanently in the second phase could gain a benefit over those recklessly keeping themselves in the first phase.
A further mechanism I have read of even more recently, is controlled by another hormone, once again optimised by a two-day eating cycle.
The third strand to the BBC programme I was discussing, looked at some scientific research on a diet scheme called Intermittent Fasting. I must admit that I had not heard of this before. However, it struck me as one of the most important ideas I have ever encountered; a practical combination of the advice to eat well that I grew up with and all the advice to restrain and restrict my eating that I have been bombarded by ever since.
Intermittent Fasting does not seem to be as new idea to the world as it is to me personally, but it is still fairly cutting edge, with no clear mainstream. Even so, at least some of the variants are the work of serious medical scientists, rather than the “alternative” charlatans inevitably drawn to anything involving dieting. Perhaps the lack of a single plan for all to follow is part of the message; adaptation to personal requirements is better than rigid dogma.
The two front-running versions appear to be a strict alternate day regime, of eating all you have the appetite for one day, then eating a hardline calorie restrictor's 600cal the next, and a slightly more relaxed 5:2 regime of five days' eating freely, then two of CR. Since starting to draft this article, I have seen a piece in one of my wife's women's magazines by the nationally famous nutritionist Patrick Holford in which he tries to incorporate the recent interest in IF into his established Glycaemic Load based approach. Holford does not take on board the key points about cycles and low-protein days, though, which is at least a difference of opinion to the likes of Dr Mosley and Prof Longo, and probably simply missing the point of the new findings. Anyway, for what it is worth, Holford's take on it advises 800cal fast days with protein meals and maintaining even blood sugar by constant snacking. I am unconvinced, as it is uspposed to be about re-establishing the natural ebb and flow of levels, but he is the expert and I the layman,so take my doubts with a pinch of salt.(Remembering, of course, that too much salt is also a major health hazard!)
If there is no Official Version yet, though, those of us with the competence and confidence to take responsibility for our own nutrition can pick our own path. I have an active job in cold conditions and used to maintain a steady weight on about 25,000cal/wk, rather more than most of my few readers are likely to need. Thus, I have devised a personally tailored version of 1000cal and low-protein, i.e. no meat, cheese or cereal on Mondays, Wednesdays and Fridays and all I can eat on the other days. After 20 weeks, I am a stone lighter. Moreover, I am as strong as I was, and seem to have only lost the internal body fat that made bending over a little uncomfortable in recent years, and, worse, correlates with medical problems like the aforesaid high cholesterol. Soon, I intend to go for a check-up and shall post results in a follow-up article, on how the critical blood measurements are looking now.
As well as yielding palpable physical benefit, Intermittent Fasting turns out to be psychologically much easier than literal dieting, in which the restrictions are made each and every day. On fast days, you start still satisfied from the preceding feast day, and by the end of the day, when you may be getting hungry, especially in the early weeks of the regime, you still have only to wait until morning for more feasting. Moreover, your body does acclimatise fairly rapidly. 20 weeks in, it is beginning to feel normal and natural not to eat heavily every day.
I would recommend adoption of Intermittent Fasting to most people, on the strength of what I have learned and my first-hand experimentation. However, this is about taking responsibility for optimising your own health. If you have any eating or metabolic related medical condition whatsoever, then get your doctor's expert advice on how quickly and intensively you can safely adopt IF. (If at all; it may be too late for you already, should Type 2 Diabetes have taken its grip on you.) I have done it unsupervised, as I was sure of my general good health and background knowledge , but I do not care to encourage others in different circumstances to take greater risks than there were for myself.