The great calorie con?
Turning our diets into a numbers game has done little for our waistlines. It’s time to recognise it’s far from an exact science – and not all calories are equal, says Joel Snape
We’ve been counting calories to keep ourselves in shape for the best part of a century now – but it seems we still haven’t got the knack.
When American nutritionist
Dr Lulu Hunt Peters published her influential book, Diet and Health:
With Key to the Calories, in 1918, she invited readers to think about what they ate not in terms of portion size, but numbers (“100 calories of bread, 350 calories of pie”…). Her guide would popularise the concept of counting calories as a method of weight control, and remained on bestseller lists for four years.
Fast-forward to modern Britain, and calorie counting is ubiquitous. The food in our shopping baskets has carried information about its nutritional value since the mid-nineties, while a voluntary labelling pledge by fast-food outlets in 2011 means that we can determine the content of our takeaways and lunchtime sandwiches, from Pizza Hut to Pret. Smartphone apps such as Myfitnesspal make tracking calories as simple as scanning a barcode.
And yet, as a nation, we’re fatter than ever. Childhood obesity is a national crisis. According to the most recent data from the World Health Organisation, more than a quarter of British adults are clinically obese, with almost two thirds officially classifiable as “overweight”. And last week, health experts warned that British millennials – that supposedly health-conscious breed born between the early Eighties and mid-nineties – are on course to be the most overweight generation since records began.
Clearly, counting calories (a recommended intake of 2,500 calories per day for moderately active men, about 2,000 calories per day for moderately active women) isn’t helping. According to estimates released last month by the Office for National Statistics, the average Briton underestimates by 50per cent how many calories they consume in a day, with men in particular kidding themselves the most.
So are we just bad at maths? Or is the calorie count as a way of staying in shape a great con? The short answer is, it depends who you ask.
“Counting calories is an oldschool, outdated approach to nutrition,” says Joe Wicks, the best-selling body coach who refuses to include calorie counts in his recipes and meal plans.
“When I was a personal trainer, I used to train people who’d exercise for two hours a day and then obsess about their calories, sometimes eating fewer than 1,000 a day – not something I’d ever recommend.
“There is no magic daily calorie intake that works for everyone; when it comes to nutrition, we’re all unique. So diets that set calorie rules for everyone are completely flawed, inaccurate and just lead to yo-yo dieting. And misery.”
While there’s nothing wrong with the maths behind what nutritionists call the “calories in/calories out” model, it puts the onus on the individual wanting to keep weight off to keep their calories balanced; to understand that if you eat 500 fewer calories than you burn every day, after a week you will have lost a pound of fat; and that a breakfast muffin packing more than 600 calories will require, on average, a full hour running on a treadmill to be burned off.
“If your goal is fat loss, you fundamentally can’t ignore calories, because they’re the maths behind achieving the body you aspire to,” says leading personal trainer Matt Roberts. “If you want to lose fat, that means convincing the body to burn its stores as fuel, which means consuming fewer calories than you use up every day. Understanding more or less where you are day-today is important.
“What we don’t want to happen, of course, is for people to become obsessed with their calories and start living every day by the numbers displayed on every food packet. It’s about getting into a rhythm of knowing what works for you and what the numbers are, and then getting on with your life.”
Part of the problem is that calorie counting is far from the exact science it is often assumed to be. The commonly-used Atwater system, named after the 19th-century American chemist who devised it,
‘Counting calories is outdated – there’s no magic number that works for everyone’
uses the number of calories in four key macronutrients – carbs, fats, protein and alcohol – to calculate the overall content of every foodstuff.
But the calorie contents we see today on food packaging are mere averages, so it’s easy for consumers to get things wrong. Short of carrying a teaspoon around at all times, it’s easy to add an extra 100 calories to your lunch in a single glug of olive oil or tablespoon of peanut butter.
But there is also evidence that the
type of food you eat affects the amount you’ll absorb: we absorb fewer calories from nuts and seeds than the Atwater system would suggest, for instance, but more from fibre-rich foods including kale, tomatoes and black beans. Cooking food also changes the amount of calories you’re likely to absorb from it: raw, natural foods typically take more energy to digest, making them effectively less calorific than heavily processed ready meals that contain the same ingredients.
“Calories out” can be just as imprecise as a metric: genetics, hormones and your weight history can all affect how much you burn during activity, making the guesstimates of your effort given by most exercise equipment almost woefully imprecise.
And then there’s the different effect calories from different foods have on the body. Take a pair of breakfast toast toppings: strawberry jam and mashed avocado. “If you fuel your body with high-sugar foods such as jam, your body fires up insulin signalling,” says Roberts. “If that sugar isn’t used up, the body will convert it into fats. But, more importantly, when you’re next low on energy, it will send out signals to eat more quick and easy energy sugars, and the same insulin reaction will happen again. This quick spike of sugars and reaction from the body is always quickly followed by an energy low and the need to fuel again, even though the body already has plenty of fat to burn.”
By comparison, the millennials’ toast-topper of choice, mashed avocado, is high in good-quality nutrients as well as healthy fats, and it would help keep blood sugar levels low. Though avocados are often held up as calorific – a single 100g serving contains 160 calories, while the same serving size of banana has fewer than 100 – “it will help prevent hunger and allow the body to switch into fatburning mode”, says Roberts.
So if it’s not the avocado brunches turning millennials into the fattest generation Britain has ever seen, what are they doing wrong? It’s tough to say. Certainly, they’ve embraced meal-delivery services such as JustEat and Deliveroo, bring often-unhealthy restaurant eating home and make upsizing a constant temptation. But they’ve also taken up home cooking via meal-packaging services including Abel & Cole and the Mindful Chef.
An increasingly sedentary lifestyle may also be a factor, with a United States study last year finding that half of millennials were as inactive as 60-year-olds, and everything from Netflix to online shopping leeching the activity out of everyday life.
But science and society also play a role: however many calorie counts food manufacturers display, they are in an arms race to produce evermore binge-worthy, “hyperpalatable” foodstuffs – the kind that triggers our hunger hormones without ever making us really full. In this sense, millennials are just victims of progress: however carefully you’re counting, it’s tough to resist the allure of crisps custom-made to drive you crazy.
Which gets to the heart of the problem with calorie counting as a way to lose weight: what actually works in real life? And the answer, again, seems to be: it depends.
“Calorie counting has actually done quite well in trials, on average, but there’s a major caveat,” says Michael Hull, a researcher at science-based nutrition site Examine.com. “Those who do well with calorie counting often do really well. You’ll find people who have counted their calories for a decade or more, after using the strategy to reliably lose weight. The most important factor is adherence” This, in the end, seems to be key. For all calorie counting’s inaccuracies, it works for people who stick to it: but if it seems like drudgery – and, for most people, it is – it won’t be sustainable.
What we really need are simpler ways to eat better and, preferably, for food companies to stop making high-calorie, insulin-spiking foods so available and so enticing.
Dr Peters – who once wrote that she hoped “sometime it will be a misdemeanour, punishable by imprisonment, to display candy as shamelessly as it is done” – would probably approve.
There is evidence that the type of food you eat affects the calories you’ll absorb from it