Breakfast is the most important meal of the day - that's what we are told and most of us would probably agree.

Its importance in fighting obesity has been endorsed by global gurus, including the U.S. Surgeon General.

Part of the same dogma is that we should eat smaller amounts of food at regular intervals - "grazing" - to avoid spikes in blood sugar and the subsequent lows, which lead to over-eating and weight gain. But these are nutritional myths unsubstantiated by any good trials. The fact is: skipping breakfast is perfectly fine.

For many people, the idea of going without food for more than a few hours will seem odd, but the reality is that we fast regularly - for ten to 12 hours overnight without any problems, and fasting is also a tenet of many religions.


Many of us feel we can never skip breakfast, let alone manage without eating for more than four hours in the day, without feeling faint, complaining of a "hypo" and reaching for a chocolate biscuit.

Yet 30 per cent of Europeans and Americans regularly flout this advice - so are they risking their health?

In Southern European countries, which have higher rates of skipping the first meal of the day, "breakfast" is often a quick espresso by the bus stop.

Despite this "risky behaviour", they are generally healthier and don't faint or binge-eat before lunch.

So why do we think breakfast is so important? Put simply: indoctrination and lobbying from the breakfast cereal companies, compounded by a whole series of poor-quality research.

These studies, often reported in the media, showed that people who skipped breakfast regularly were, on average, more likely to be obese, had higher blood sugar levels and were more likely to over-eat later in the day.

The problem with these studies (and this, sadly, exemplifies studies in the field of nutrition that tend to reinforce dogma) is that they don't show how skipping breakfast might cause obesity.

Furthermore, studies showing a link between obesity and missing the meal are biased by the bad habits of many breakfast skippers: we know they are more likely to be less well-educated and ignore health advice, eat less fibre, smoke and avoid sport.

All of which can lead to obesity and poor health regardless of breakfast.

The real and convincing evidence of the effects of skipping breakfast comes from long-overdue clinical trials. These avoid bias as they allocate people at random to eat or skip breakfast - this way, unhealthy people are split between the groups.

There have been six randomised studies - five in the past two years.

And guess what? There was no evidence of any weight gain or metabolic problems such as type 2 diabetes.

Indeed, in four of the six trials, the breakfast skippers - who, overall, were eating less - lost weight, contrary to expectations.

(While it's been reported that children could suffer mentally at school if they don't have breakfast, the evidence is equally weak and biased and we are still awaiting proper trials.)
Clearly, as in all studies, these are averages, and some people will feel they really need their breakfast while others don't. Some of this is cultural and some may be genetic.

The studies we've done with twins at King's College London have shown a clear gene influence on whether you are a morning person or an evening person, and these body-clock rhythms undoubtedly affect the times we prefer to eat.

So we should probably let our bodies guide our choice of having breakfast, rather than dubious studies and dogma.

The three-meals-a-day routine is a modern invention, only coming to the West in the Victorian era.

We don't know for sure, but suspect our early ancestors had only one main meal a day, as stopping to set up picnic tables at noon in the middle of a hunt would have been tricky.

The Ancient Greeks, Persians, Romans and early Jews all ate one big meal per day - usually in the evening, to celebrate the day's work.

In England, it wasn't until the 16th century that two meals were introduced.

A proverb at the time proclaimed this was the healthy new recipe for long life: "To rise at six, dine at ten, sup at six and go to bed at ten makes a man live ten times ten."

The habit of two meals a day was still the norm in the 19th century even among the upper-classes, and only changed recently.

Increasing our fasting periods by cutting out some meals could be better for us, even if we consumed the same daily calories.

A 2007 U.S. government study explored this, with 21 volunteers given the same food content and calories over eight weeks as one giant meal a day or three, small, divided meals. Then, after a break, the volunteers swapped.

Throughout the six-month period, each volunteer's weight remained within 2 kg of their initial figure.

There were no significant differences in heart rate, body temperature or most blood tests.
As expected, the single meal produced more feelings of hunger, but also significant reductions in body fat and in the stress hormone cortisol.

So there is no evidence that skipping two meals will do you any harm and may have benefits.

Even a Mediterranean style of eating, ie, two main meals, regardless of calories, looks to be healthy.

It could be that the benefits of fasting lie in its effect on the trillions of healthy microbes in our guts.

The latest research shows that our gut bacteria undergo major changes during fasting, with a brief surge in bacterial species resulting in a helpful cleaning process for our gut lining - improving our immune defences and reducing the risk of obesity and diabetes.

This could be the key to the success of intermittent fasting diets such as the 5:2, which trials have shown help with weight loss and improve blood profile (such as blood sugar and cholesterol).

It's time to bury the fasting myth for good and let our bodies - not wealthy food companies - decide if we want to skip breakfast.

* Tim Spector is a professor of genetic epidemiology at King's College London and author of The Diet Myth: The Real Science Behind What We Eat.