Timing is everything: when you eat is as important as what you eat
We look into how this ties into eating habits in this part of the world
“Breakfast like a king, lunch like a prince and dine like a pauper.” This old adage might sound like the sort of dubious dietary wisdom peddled by grandmothers down the generations, but new research suggests there might well be something in it.
Food is something we all have in common and nutrition is one of the most heavily researched subjects in science. Yet, surprisingly, there is little evidence to answer three of the most basic questions: how many meals a day we should eat, when we should eat them and how big they ought to be.
Now, in one of the largest studies of its kind, United States and Czech researchers have come up with some surprising answers – and demonstrated that it always pays to listen to your grandmother.
A team led by scientists from the School of Public Health at Loma Linda University, California, analysed dietary data from 50,000 relatively healthy North American adults over seven years. What they found may have profound implications for affluent societies everywhere – but especially for people in Middle Eastern countries such as the UAE, where obesity and diabetes are on the rise and a long-term public health crisis is brewing.
The researchers took as many variables into account as possible, from the average daily energy intake, the number of meals and snacks consumed each day and the length of the overnight fast, to the amount of sleep, television viewing and exercise.
They were looking for a single outcome – an increase or decrease in Body Mass Index, or BMI, which is a way of assessing body weight in relation to height.
Some of their conclusions, published in the Journal of Nutrition last month, smack of common sense. Eating one or two meals a day, for example, “was associated with a relative decrease in BMI compared with three meals a day”. Eat less, in other words, and you’ll weigh less. And, yes, any kind of snacking counts as a meal. Likewise, “participants who ate more than three meals a day experienced a relative increase in BMI: the more meals and snacks per day, the greater the increase”.
So far, so obvious. But then come the breakthrough findings which, if applied to our everyday eating habits, could render the fad-diet industry redundant overnight – and, says Gary Fraser, professor of public health at Loma Linda and a co-author of the paper, “clearly have some potential relevance to the cultural situation in the UAE”.
People who ate breakfast, the researchers found, “experienced a relative decrease in their BMI compared with breakfast-skippers”. Those who went farther, however, turning the eating day on its head to make breakfast the biggest meal of the day, did even better than those who ate their largest meal at lunchtime or dinner.
However, scrapping dinner altogether gave the best results. The study found that “the BMI of subjects who had a long overnight fast” (of 18 hours or more) decreased compared even with those who had a medium overnight fast, of between 12 and 17 hours.
In other words, if you eat breakfast at 8am, ideally you shouldn’t have eaten anything since 2pm the previous day – admittedly a tough call, especially when one of your colleagues brings round that large box of chocolate dates mid-afternoon.
Compare this advice to the pattern of life in the UAE, where temperatures and tradition combine to favour long, late-night, multi-generational family dinners, and snacking is almost obligatory in the omnipresent malls. Effecting such a dramatic change in eating patterns would be a tough call for many here, says Caroline Bienert, a nutritionist who spent 10 years helping clients in Dubai and now divides her time between the UAE and Germany.
“The biggest challenge in life is changing your nutritional habits,” she says. “If it were so easy, then everyone could, and would, do it.”
Emiratis, she suggests, face unique challenges, created in part by the relatively rapid acceleration of the country’s status from poor to wealthy, which has left the population struggling in a time of plenty with a metabolism formed by generations of want.
The hot weather discourages outdoor exercise for locals and expats alike and, in addition to offering air-conditioned refuge from the heat, the many malls tempt bored shoppers with endless cafes and fast-food outlets. Women who don’t work are particularly at risk, she says. “Even shopping gets boring after a while, and eating is something to do.”
In 2014, the World Health Organisation ranked the UAE 14th in the world for the prevalence of obesity among its population. With an estimated 28.1 per cent of adults obese, this, said WHO, represented “the weight of affluence … high incomes and a taste for fast-food and sugary drinks have pushed nationals of the United Arab Emirates into the [global] obesity club”.
Look at photographs or film footage taken in Dubai 40 or 50 years ago, says Bienert, “and you see only very slim people, doing hard physical work on limited diets”. She believes action needs to be taken now to avert a potential public health crisis down the line.
As reported in November, the number of cases of diabetes in the UAE has risen 35 per cent since 2014, with obesity the principal factor in most cases. Obesity itself is an increasingly alarming problem, among adults and children alike.
A study carried out last year among 15,532 schoolchildren in Ras Al Khaimah found 40 per cent were overweight, 24.4 per cent obese and 5.7 per cent extremely obese.
The Loma Linda study looks at the long-term effects of altering eating patterns. “We don’t know whether there would be more rapid acute effects of a change in meal patterns on BMI,” says Fraser. “We are talking about very small year-by-year changes that nevertheless add up over the decades.
“The effect of preferring to eat most calories earlier in the day is to diminish the weight gain before age 60 years, and to increase the natural weight loss after age 60 years.”
For instance, the researchers say that, on average, a man with a traditional eating pattern who is 180 centimetres tall and weighs 79 kilograms at the age of 30 would be expected to weigh 87kg by 60, falling to 82kg by 80.
But, says Prof Fraser, “if he had had a meal pattern of eating most calories earlier in the day during his life, his weight would have only increased to 83.4kg by age 60 and then decrease to 76.2kg by 80.”
What is BMI?
BMI is the product of a simple equation: your weight divided by the square of your height (the square of a number is found by multiplying it by itself). So if you weigh 80 kilograms and are 1.82 metres tall, your BMI (80 divided by 3.31) is 24.1. According to the four BMI categories approved by the World Health Organisation, this means your weight is healthy: a BMI under 18.5 is deemed to be underweight, 18.5 to 24.9 indicates a healthy weight, 25 to 29.9 is above the ideal range and 30 and above is classed as obese.
So if you weigh the same as your taller friend, 80kg, but stand only 1.72m tall in your socks, then you are over your ideal weight.
BMI can only ever be a rough generalisation – it does not, for example, take account of people who exercise regularly and carry a lot of muscle. But as a yardstick to compare and contrast individuals in society, or taking part in a large trial, it works well.
This isn’t the first time that reduced frequency of meals has been associated with improvements in weight and health, although previous research has focused on patients who already had Type 2 diabetes. In 2014, a study published in the journal Diabetologia compared the effects of two types of low-energy dietary regimes on Type 2 diabetics. The conclusion was that eating two larger meals a day – breakfast and lunch – was better than eating the same number of calories spread over six smaller meals.
Concentrating the calories into only breakfast and lunch reduced body weight, fatty liver disease and fasting blood glucose (a high level is indicative of diabetes). It also reduced the body’s resistance to insulin.
Insulin allows body cells to store glucose as fuel. Obesity can build up resistance to insulin, which the body then tries to counter by producing more insulin, which leads to high levels of blood sugar and Type 2 diabetes.
The Loma Linda University study could be said to be flawed because, although large, it was carried out among a self-selecting group of individuals – 50,660 adult members of the Seventh-day Adventist Church in the US and Canada. The university is one of several in North America affiliated to the church.
However, in one respect at least, this element of self-selection also serves to make the findings even more relevant to Islamic societies: 90 per cent of those taking part abstained from consuming alcohol.
Updated: August 14, 2017 10:43 AM