Читать книгу Breakfast is a Dangerous Meal: Why You Should Ditch Your Morning Meal For Health and Wellbeing - Terence Kealey, Terence Kealey - Страница 26

Harvard has for years been studying the 51,529 middle-aged professional white men of the Health Professionals Follow-Up Study (HPFS). These men were recruited in 1992, and it happened that some 17 per cent of them were breakfast skippers, which is a typical percentage.

At least three important breakfast-related findings concerning weight gain, type 2 diabetes and coronary heart disease have apparently come out of this politically incorrect Follow-Up Study on middle-aged upper middle-class white men:

 In 2007 the scientists of the HPFS reported that ‘the consumption of breakfast may modestly contribute to the prevention of weight gain compared with skipping breakfast in middle-aged and older men’1

 In 2012 the scientists reported that ‘breakfast omission was associated with an increased risk of type 2 diabetes’2

 And in 2013 the scientists reported that ‘eating breakfast was associated with significantly lower coronary heart disease risk in this cohort of male health professionals’3 [all my italics].

But we would be hasty to accept the associations as causations. First, the breakfast skippers are unquestionably following risky lifestyles: men who skipped breakfast smoked three times more, exercised less, drank more coffee and alcohol, and ate significantly less healthy foods than men who ate breakfast. Breakfast skippers were also 21 per cent more likely to snack, were a bit fatter, and were more likely to eat late at night. In the 2013 coronary heart study, moreover, the researchers also found that breakfast eaters were more likely to be married (marriage is good for men’s health)^fn1 and that skippers were significantly less likely to get regular health check-ups.

In their three breakfast studies, the Harvard scientists of the HPFS tried to correct statistically for those confounding factors, but I suspect they failed to do so – not because they didn’t try hard enough but because there are simply too many unknown factors. So, for example, no correction was made for social support (people with good networks of friends tend to live longer than the friendless,⁴ and they also tend to eat breakfast,⁵ which does not tell us that eating breakfast is a good way of keeping friends, nor that eating breakfast is healthy, but rather that compliance with conventional human norms such as friendship leads to better health outcomes, even if certain aspects of that compliance – viz breakfast – are unhealthy).^fn2 Until correction has been made for the full panoply of risks, we simply cannot accept Harvard’s claims that breakfast is safe.

Moreover, the HPFS scientists have finally confirmed that the satiety hypothesis has been disproved, and in their 2013 paper they reported that breakfast eaters consumed 123 calories a day more than the skippers. Cumulatively, this should lead to the breakfast eaters putting on a pound of fat (0.5 kg) more, every month, than the skippers, so Harvard’s own data suggest that breakfast is unhealthy.

Yet the Harvard HPFS researchers remain wedded to breakfast being healthy as a cause-and-effect paradigm. So though in 2013 they wrote, very properly, that ‘it is possible that eating habits could be a marker of lifestyle consistency or general health-seeking behaviour’, they seem not to really believe in correlation. So in 2007, for example, before they recognised that breakfast eaters ate more calories, they wrote: ‘The prevalence of overweight and obesity has rapidly increased in recent decades … The prevalence of people not consuming breakfast every day has increased over the last decades … Breakfast consumption could reduce total calorific intake during the day by consuming less food during the day,’⁶ which was a clear statement of the linear breakfast paradigm of:

eat breakfast → satiety → consume less food → lose weight

or vice versa

skip breakfast → no satiety → consume more food → increase weight

And though the Harvard scientists have since had to shed that particular cause-and-effect paradigm, they seem to have adopted stress as a cause instead. Dr Leah Cahill was the lead author of the 2013 HPFS coronary heart disease study, and she revealed what she believes to reporters from Texas A&M University’s newsletter and Forbes magazine, who wrote that: ‘Cahill says that fasting is a stressful state for the body, so prolonging the fast by not eating when you wake up amplifies the stress.’⁷

Dr Cahill repeated the same message when she spoke to the BBC, saying that skipping breakfast and so not ‘breaking fast’ put extra strain on the body.⁸ But I can find no actual evidence from Harvard showing skipping breakfast to be stressful.

Indeed, another clue that the successive HPFS studies do not provide the final word on breakfast was shown by their contradictory results over eating frequency: their different studies could not agree on the optimal numbers of meals to be eaten daily:

i In 2007 (the weight gain study) the HPFS scientists reported that ‘an increasing number of eating occasions … was associated with a higher risk of 5-kg weight gain’

ii In 2009 (the type 2 study) they reported that ‘compared with men who ate 3 times a day, men who ate 1–2 times a day had a higher risk of type 2 diabetes’ (i.e. a decreasing number of eating occasions was associated with a higher risk of type 2)

iii And in 2013 (the coronary heart disease study) they reported that ‘No association was observed between eating frequency … and risk of coronary heart disease’ (all my italics).

Since breakfast skipping is itself a variation in meal frequency, these contradictory findings suggest not that breakfast skipping leads to weight gain, diabetes and coronary heart disease but, rather, that a separate set of factors leads both to breakfast skipping and to the diseases.

Cambridge UK: Harvard is situated in Cambridge, MA, but the scientists in Cambridge UK are also fans of breakfast. In one study the Cambridge epidemiologists wanted to know how breakfast determined weight gain, so they performed a cross-sectional or ‘snapshot’ study. They recruited some 6,800 middle-aged men and women, some of whom, of course, happened to eat light breakfasts, while others happened to eat big ones.⁹

The research team asked their subjects (i) what they typically ate for breakfast, and (ii) what else they typically ate during the course of the day. The research team then weighed them, finding that the more food they ate at breakfast, the more calories overall they consumed, yet the lighter they weighed, i.e.:

eat breakfast → consume more calories → weigh less???

The research team had apparently, therefore, reaffirmed the (in)famous breakfast paradox: the team had confirmed that satiety is a myth (the more the subjects ate at breakfast, the more they ate overall), but since the breakfast eaters were slimmer than the skippers, the paradox had apparently re-emerged. But paradoxes emerge only when a false paradigm hits reality, so which paradigm were the researchers working to? Here is an extract from the introduction to their paper: ‘[Studies show that] regular breakfast consumption is associated with successful maintenance of weight loss, suggesting that consuming fewer calories in the morning or skipping breakfast could contribute to the development of obesity.’

So the researchers were working to a cause-and-effect paradigm:

eat breakfast → eat more food overall → lose weight

or

skip breakfast → eat less food overall → gain weight

which makes no sense. But if we adopt a different paradigm:

No history of dieting, therefore brisk metabolism

↓

therefore can afford to eat breakfast

↓

yet still lose weight

or alternatively:

History of dieting, therefore slow metabolism

↓

therefore cannot afford to eat breakfast

↓

yet still gain weight

then we have a model that is not paradoxical. So if we rewrite the introduction to the paper, we can keep the first half of the sentence, which contains the facts, but we can change the conclusion: ‘[Studies show that] regular breakfast consumption is associated with successful maintenance of weight loss, suggesting that slim people can afford to eat breakfast and to consume more calories.’

The Cambridge researchers then reinforced their observations by performing a cohort study analogous to the one Hill and Doll performed on smokers. They followed their subjects over the next 3.7 years, finding that on average:

 all their subjects gained weight as they aged

 the people who ate the lightest breakfasts gained some 1.25 kg

 those who ate the biggest breakfasts gained only some 0.8 kg

 even though they apparently consumed, on average, 82 calories a day more than the small breakfast eaters.

Yet again, the researchers had apparently uncovered the (in)famous paradox. But they then did an odd thing. They interpreted their findings to conclude that the

‘redistribution of daily energy intake, so that a larger percentage is consumed at breakfast and a lower percentage is consumed over the rest of the day, may help to reduce weight gain in middle-aged adults.’

Yet that is not the full conclusion of the paper’s own logic or data: the researchers showed that the more breakfast their subjects ate, the more food they also ate. So using the researchers’ own logic and their own data, the full conclusion is: ‘To keep slim, eat more at breakfast, and ensure your total food intake also goes up.’ Which makes no sense, which is why I assume the Cambridge scientists didn’t draw the logical conclusion of their own data.

Cambridge and Dr Farshchi: The Cambridge scientists knew their findings were paradoxical, so to explain them they invoked the work of Dr Farshchi, from the University of Nottingham.

Dr Farshchi was a researcher who had examined the insulin responses of ten women, finding that when they skipped breakfast, their circulating levels of insulin rose (and vice versa, the levels of insulin in breakfast eaters fell).¹⁰ Since insulin makes you fat, the Cambridge researchers suggested, the paradox was therefore solved:

skip breakfast → secrete more insulin → get fat

or

eat breakfast → secrete less insulin → stay slim

Hold on. Eat breakfast and secrete less insulin? Skip breakfast and secrete more? The whole point of insulin is that it rises when we eat (I discuss this at greater length later), so what’s happening when the more that people eat, the less insulin they secrete?

Well, it turns out that when Dr Farshchi’s subjects ate breakfast, they ingested less food overall. And vice versa: when they skipped breakfast they ate more overall. They were anomalous. This was something that Dr Farshchi signposted himself, writing that his findings were ‘at variance with previous studies’. (The previous studies show, of course, that breakfast eaters, like the Cambridge team’s subjects, consume more calories.)

So Dr Farshchi’s findings cannot resolve the Cambridge researchers’ paradox, because the Cambridge team’s breakfast eaters ingested more food overall whereas Dr Farshchi’s breakfast eaters ingested less.

I hope I have not been unfair to the Cambridge scientists, whose papers are, rightly, widely read, and whose data can be trusted unreservedly, and who are scrupulously honest, but we do need to know if eating breakfast is good or bad for us, and if we adopt their paradox we have to conclude (in my summary of their logic) that:

to keep slim, eat more at breakfast and ensure your total food intake also goes up

whereas if we refuse to accept a paradox, then the data suggest that:

to keep slim, skip breakfast, which will lower your total food intake.

The choice is black or white, but the consequences may be life or premature death.

And though I totally respect the Cambridge scientists’ data, I do regret one set of facts they seem to have omitted: they appear to have excluded from their analysis all the subjects who died or fell ill over the 3.7 years they monitored them. But it is a principle in epidemiology that the most important potential end-point of an investigation is not a proxy measurement (such as obesity) but the end-point itself, namely death. The team might still have those data, and it would be good to see them published. Do they show if breakfast kills or cures?