Читать книгу Breakfast is a Dangerous Meal: Why You Should Ditch Your Morning Meal For Health and Wellbeing - Terence Kealey, Terence Kealey - Страница 23

When our first child was born, in 1991, the world was still in the grip of the epidemic of cot deaths that had, unexpectedly, erupted some years earlier. To minimise the risks to our child, my wife and I were told to lay her to sleep on her tummy. But when our second child was born, in 1993, we were told to lay him on his back. It transpired that more than half of cot deaths before 1992 had occurred because babies had been laid to sleep on their tummies; and they were sleeping on their tummies because studies had shown that sick babies in intensive care units did better on their tummies. Fair enough. But that observation was then extrapolated, without proper testing, to healthy babies at home; and those do worse on their tummies, so their death rates rose.³

Perhaps the best-known example of compliance danger is provided by Stevie Wonder, whose blindness was caused by his having been given, as a sick baby, 100 per cent oxygen to breathe. Routinely giving 100 per cent oxygen to sick babies – regardless of their illness and regardless of their actual need for extra oxygen – was once conventional until doctors realised that the contemporary epidemic of infant blindness was being caused by the excessive oxygen that, by stimulating the uncontrolled growth of certain cells in the eyes, was destroying the babies’ vision.

We can go on multiplying the recent examples of doctors being wrong (I’m not talking leeches here, I’m talking about modern doctors). Consider hormone replacement therapy (HRT) for the menopause. For half a century this was lauded by doctors, and for years ‘it was considered malpractice if you did not prescribe HRT for menopausal women.’⁴ Only with the publication of the two Women’s Health Initiatives in 1992 did the breast cancer story emerge, and HRT is now prescribed with circumspection.⁵

These stories are relevant to breakfast because they confirm that modern doctors can sometimes be wrong in their advice, advice over breakfast not excluded.

2. People under-report their food intake: Another breakfast confounder is that obese people tend to under-report their food intake, so the association between obesity and breakfast skipping may be simply a reporting artefact: obese people may be eating breakfast, and thus getting fat, but they may be reporting themselves as not eating breakfast.⁶

I have no doubt that large people, like most people actually, under-report their eating, though large people may be particularly extreme under-reporters. In the days when, as a young doctor, I ran metabolic clinics, I would be astonished by the vehemence with which some overweight and obese patients denied the obvious fact that they ate excessively. I remember one very large lady who denied eating between meals, whose daughter approached me discreetly to say that her mother ate biscuits all day, claiming ‘they didn’t count.’

3. Breakfast skipping is not properly defined: In 2008 a philosopher, Peter Vranas of the University of Wisconsin, noted that different research groups were using up to twenty-four different definitions of breakfast skipping. These ranged from never consuming a calorie before midday, to never consuming one before 10.00 a.m., to consuming a light drink of milk or fruit juice on occasion or regularly, to eating a full breakfast but only at weekends, etc., etc. And Vranas found … well, let the title of his paper speak for itself: ‘Breakfast skipping and body mass index among adolescents in Greece: whether an association exists depends on how breakfast skipping is defined’.⁷

This was an alarming finding because it suggested that different research groups had published different conclusions based solely on different definitions of breakfast skipping.

Vranas has shown, in short, that much of the epidemiological literature may have been distorted by loose definitions. We probably need more philosophers in this area.

4. ‘Kick-starting’ metabolism: On eating a meal, a person’s metabolic rate increases as they consume energy in digesting the food (which is why some people feel hot or sweaty during or after a meal). So a number of researchers have suggested that if (if!) the eating of breakfast is slimming, perhaps that is because eating breakfast stimulates metabolism all day long, thus burning calories all day long. That suggestion is echoed commercially: easyJet’s on-board magazine Bistro & Boutique for March 2015 carried a claim from the CEO of Moma, a porridge company, saying that breakfast ‘kick starts your metabolism’.⁸

But in 2014 a research team led by James Betts from the University of Bath, UK, performed the most comprehensive study to date.⁹ Studying a group of subjects over six weeks, half of whom ate breakfast and half of whom did not, Betts first confirmed that breakfast satiety is a myth: when his subjects ate breakfast they consumed 539 extra calories overall during the day (i.e. skippers consumed 539 fewer calories overall). But then he found that, after six weeks of daily breakfast, ‘contrary to popular belief there was no … increased resting metabolism’: i.e. he’d exploded the myth that breakfast kick-started metabolism. Dr Betts went on to tell the Daily Mail:

The belief that breakfast is ‘the most important meal of the day’ is so widespread that many people are surprised to learn that there is a lack of scientific evidence showing whether or how breakfast may directly cause changes in our health. It is certainly true that people who regularly eat breakfast tend to be slimmer and healthier but these individuals also typically follow most other recommendations for a healthy lifestyle, so have more balanced diets and take more physical exercise.¹⁰

Indeed, in a similar study on obese people, Betts concluded that: ‘In view of the public perception that breakfast consumption facilitates weight management, it is paradoxical that 10 of the 11 individuals in the breakfast group gained weight.’¹¹

As Betts told the Independent on 24 March 2016, breakfast ‘is not going to make you lose weight’ so there’s no need to hypothesise a mythical metabolic kick-start to account for a mythical weight loss. There’s no if.

And Betts himself – a man who knows more about breakfast than most of us – generally skips it.

5. Breakfast skippers are owls, not larks: A recent study from Finland on over 6,000 people showed that evening types were two and a half times more likely to develop type 2 diabetes than were morning types.¹² That dramatic finding is significant because a separate study has shown that evening types often skip breakfast.¹³ These two studies thus provide a strong correlation between breakfast skipping and the development of type 2 diabetes, but the underlying cause appears to be so-called ‘social jet lag’.

Evening types or owls seem to suffer from social jet lag because, having gone to bed late, they are always having to wake earlier than they would like. These owls compensate for tiredness or ‘sleep debt’ during the week by lying in over the weekend, but in the meantime they suffer from stress and depression. So, for example, one study from Munich, reporting on some 500 volunteers, discovered that the more someone was an owl, the more likely they were to smoke and drink excessively.¹⁴

Equally, another study from Chicago and Bangkok, reporting on patients with type 2 diabetes, showed that the more a person was an owl (which was determined by how much extra sleep they took – and by how late they got up – at weekends) the more likely they were to skip breakfast and the more likely they were to be overweight and to have severe diabetes. They were also more likely to develop hypertension.¹⁵

These studies showed, therefore, that the breakfast skipping of social jet lag was – like the smoking and drinking and stress and depression and obesity and diabetes of social jet lag – just one of the complications of the social jet lag: the skipping did not cause the complications, it was one more to add to the list.¹⁶

The damage caused by social jet lag is mediated by sleep deprivation, but social jet lag is, of course, not the only cause of sleep deprivation, and a research group from Okayama, Japan, has shown that people who have difficulty in getting to sleep for whatever reason, or who wake up at night for whatever reason, are also two and a half times more likely to develop type 2 diabetes.¹⁷ And a recent study from Sweden on healthy young men who were kept awake artificially showed that on the following day they ate significantly more food.¹⁸

Sleep deprivation also damages by raising the levels of stress compounds in the blood including cortisol, certain pro-inflammatory chemicals and free fatty acids.¹⁹ These promote insulin-resistance and thus obesity and type 2 diabetes.²⁰

From all these different studies, therefore, it appears that:

So we have uncovered yet one more association between breakfast skipping, obesity and diabetes which owes nothing to cause and effect but which, rather, is rooted in a common factor of sleep deprivation.^fn1

Finally, a good Darwinian would be compelled to find a compensatory benefit to being an owl: if owls are less healthy than larks, they should surely have gone extinct by now, yet it has been reported that night owls are more intelligent than morning larks, which perhaps explains their survival.²¹

Recent (welcome) developments: As we increasingly understand the links between breakfast skipping and obesity to be an association, not causation, it’s good to report that scientists are, today, increasingly careful not to conflate them. So, for example, a 2010 overview of sixteen different European studies that found breakfast skipping and obesity to be linked nonetheless concluded that since ‘almost all of the data … were gathered from observational studies … causality should not be assumed’.²² Epidemiological sanity is beginning to win out.

Much breakfast epidemiology has only confirmed what Michael Marmot from University College London established long ago, namely that in the west the upper socio-economic groups outlive the lower groups by about seven years, probably because they experience less stress.^fn2 And since the upper socio-economic groups tend to comply with the conventional advice to eat breakfast and other regular meals, while the lower groups tend to eat less regularly, much epidemiology reflects only a correlation between frequent eating and longevity.