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Myth No. 3: Breakfast is slimming

Pundit after pundit asserts that breakfast produces satiety (from the Latin satis, enough). Breakfast, it is claimed, fills people’s stomachs and raises their blood sugar levels so they eat less at subsequent meals. Is this true?

There are of course peer-reviewed scientific papers that make such assertions, and a man who has written many of them is Dr John de Castro, a Texas psychologist, who in 2004 wrote: ‘we found that when individual subjects ate a larger than mean proportion of their total intake in the morning, they ate significantly less over the entire day.’¹ Which apparently means that the more someone eats at breakfast, the less they eat during the rest of the day. De Castro attributed this to satiety. Here is his model:

Eat breakfast → satiety → eat less at lunch → lose weight

This is a powerful model, which at first sight seems to make sense. But most scientists find the exact opposite. In a recent study David Levitsky and Carly Pacanowski of Cornell University, New York, showed that when subjects were provided with light breakfasts (approx. 350 calories) their intake at lunch was completely unchanged: i.e. those 350 breakfast calories did not cause a compensatory fall in lunch calories, so on eating breakfast their daily intake went up by 350 calories. Moreover, when the subjects ate full breakfasts of around 624 calories, they reduced their lunch calories by only about 144 calories, causing a net increase of 480 calories a day.² No wonder Levitsky and Pacanowski concluded that ‘skipping breakfast may be an effective means to reduce energy intake.’ The Levitsky and Pacanowski model is, therefore:

Skip breakfast → consume less food → reduce energy intake

or vice versa

Eat breakfast → consume more food → increase energy intake

And what made Levitsky and Pacanowski’s study so significant is that they showed that ‘these data are consistent with published literature.’ That is to say there is widespread agreement that de Castro’s satiety hypothesis is wrong and that eating breakfast increases energy intake.

Indeed, an overview of forty-seven of the most authoritative breakfast studies performed between 1952 and 2003 confirmed that around 20 per cent of children and adults skip breakfast, and that ‘breakfast eaters generally consumed more daily calories.’³ So, contrary to myth, eating breakfast piles on the calories. How then do we account for de Castro’s finding that ‘when individual subjects ate a larger than mean proportion of their total intake in the morning, they ate significantly less over the entire day’?

Dramatically, Dr Volker Schusdziarra and his colleagues from the obesity clinic at the Technical University of Munich in Germany dismiss de Castro’s breakfast conclusions as a statistical illusion.⁴ On studying a cohort of subjects, Dr Schusdziarra found that, left to their own devices, people tend to eat fairly consistently in the mornings (i.e. breakfast is a relatively fixed-sized meal, because it is a habit) but people tend to eat inconsistently later in the day: on some days (for whatever reason – Aunt Flo’s birthday party, a celebratory restaurant meal) people will eat more at lunch and dinner, whereas on other days (for whatever reason – not feeling well, being rushed at work) people will eat less at lunch and dinner.

Yet because the intake at breakfast is reasonably fixed, on the days that people ate large lunches and dinners, the proportion of their food intake from breakfast was small, while on the days they ate small lunches and dinners, the proportion of their food intake from breakfast was large. So it looks as if:

small breakfasts → large overall food intake

And

large breakfasts → small overall food intake

But these are illusions based on the greater variability of consumption at lunch and dinner, and the real model is:

large intake at lunch and dinner → breakfasts correspondingly small, relatively

And

small intake at lunch and dinner → breakfasts correspondingly large, relatively

Schusdziarra was rightly respectful of de Castro’s data; it was only his interpretation he challenged. And this, as will be seen, is the theme of this book: the accumulated breakfast data of literally hundreds of scientists is almost always sound (it’s amazing how much breakfast research has been performed), but the findings have been systematically misinterpreted.

Satiety and social eating

Satiety can of course be real. Children up to the age of 3 will eat only in response to satiety signals, but by the age of 5 their appetites are already being modified by other signals – social signals. So Brian Wansink of the Cornell University Food and Brand Laboratory reported in his 2006 book Mindless Eating that when researchers from Pennsylvania State University:

gave three- or five-year-old children either medium-size or large-size servings of macaroni and cheese, the three-year-olds ate the same amount regardless of what they were given. They ate until they were full and then they stopped. [But] the five-year-olds rose to the occasion and ate 26 percent more when they were given bigger servings. Almost exactly the same thing happens to adults. We let the size of the serving influence how much we eat.⁵

In her 2011 book Eat What You Love, Love What You Eat Dr Michelle May listed the social and psychological signals that can override satiety in encouraging us to overeat.⁶ These include loneliness, depression, anxiety, stress and boredom. Or, in the words of Comic Book Guy from the 1997 episode of The Simpsons (#8.17), ‘My Sister, My Sitter’: ‘Loneliness and cheeseburgers are a dangerous mix.’

Distraction, too, can be a major eating stimulant: a recent overview of twenty-four separate research papers concluded that people who eat while being distracted (munching crisps while watching television, say) increase their food intake on average by 76 per cent.⁷ This is because distracted eaters not only eat mindlessly but also retain little memory of having eaten, so they approach their next meal assuming they must be hungry. There is wisdom behind the old injunction of ‘not eating between meals’.

Another social signal is company: in a series of studies for which he is rightly well known, John de Castro reported that, if you eat with one other person, your consumption goes up by 35 per cent; if you eat with three other people, your consumption goes up by 75 per cent; and if you eat with six other people your consumption goes up by 96 per cent.⁸ Which is why Wansink wrote in Mindless Eating that weight ‘can be contagious’.⁹

And we humans are not the only social animal whose eating is stimulated by company: as long ago as 1929 it was discovered that, when a solitary chicken was replete and had stopped eating, the admission of another chicken into its cage would prompt it to start eating again.¹⁰ The same behaviour is true of pigs, fish, rats, gerbils, puppies and primates. Social animals eat socially. Brian Wansink has even shown that the amount of food we order in a restaurant is influenced by the mass of the waiter: ‘diners were … four times more likely to order desserts … when served by heavy wait staff with high body mass indices.’¹¹

Our species has been honed by aeons of evolution to seek social approval, so our eating is determined as much by our social and psychological choices as by our satiety, which we can override in daily practice.

(In this book I follow academic fashion in describing the extraordinary contemporary incidence of obesity and diabetes as ‘epidemic’ or ‘pandemic’. Originally, epidemics and pandemics were defined as diseases that spread from person to person, yet because overeating is socially transmittable, the use of the terms to describe obesity and diabetes may be defensible.)

An exception: Although humans generally eat more in company, a Vanderbilt University research group showed in a ‘get-acquainted’ session in a psychology laboratory that human females – unlike human males – will snack up to 75 per cent less in the presence of a desirable member of the opposite sex, which caused the researchers to speculate on the role of feminine self-presentation in the development of anorexia.¹² This female trait was satirised by Aldous Huxley in chapter 19 of his 1921 novel Crome Yellow:

He noticed with surprise and a certain solicitous distress that Miss Emmeline’s appetite was poor, that it didn’t, in fact, exist. Two spoonfuls of soup, a morsel of fish, no bird, no meat, three grapes – that was her whole dinner …

‘Pray, don’t talk to me of eating,’ said Emmeline, drooping like a sensitive plant. ‘We find it so coarse, so unspiritual, my sisters and I.’

But some time later the protagonist finds a secret door, which he opens to find the sisters tucking into a good lunch. The protagonist promptly blackmails one of the sisters, Georgiana, into marrying him.