The great big diet myth: why everything you thought you knew about calories is wrong

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e’re all used to the concept of calorie counting — in fact it’s been central to our thinking on weight-loss for more than a century — and now, in the UK it’s become even more visible. As of April the government made it compulsory for restaurants that employ more than 250 staff to display the calorie counts of their dishes on the menu. The initiative, designed to tackle the UK’s massive obesity crisis, has sparked a national conversation about whether the inclusion of the information will have any impact on people’s waistlines (and what it’ll do to their mindsets) facing criticism from experts who argue calorie counting is an outdated concept and “fundamentally flawed” method for calculating what we eat. They highlight that we’re all very different when it comes to metabolizing food and say it’s time we ditched the calorie altogether.

Rhiannon Lambert, who’s been a nutritionist for 10 years, is among those taking a stand against calorie labeling, saying it only tells us a fraction of the story. “We eat food, not numbers,” says the 32-year-old who has a nutrition clinic on Harley Street. “Do I think calories on menus will help solve obesity? No. Do I think it’ll impact people’s relationship with food? Yes.”

The reason for her objection is that everyone processes foods in different ways meaning that the number of calories listed on the packet or menu most likely will not apply to you.

“Of course a basic understanding of calories can be beneficial and you can’t deny the fact that if you eat more than you use, it gets stored as body fat and it’s important to understand that some dishes have a lot of energy in them compared to others but the way we’re calculating them and applying them to ourselves is inaccurate so the concept of calorie counting is fundamentally flawed.”

The simple number takes into account neither the constituents of the food, which affect how we absorb it and how much energy we get from it, or the fact that we’re all different and process food differently — not to mention all our differing lifestyles.

“The absorption will be different for a dish that’s high in fiber or good fats as opposed to an ultra-processed item that’s high in sugar and salt and that will affect how much energy we get from it,” she explains, which is something calorie counts don’t tell you.

“As well as that we have our unique differences which impacts how we use food. Some people thrive off a high protein diet, others off a high carb diet.” And other factors like people’s age, size and physical activity levels all have an impact too.

Besides, food does more for us than affect whether we can fit into our favorite jeans or not. “Food should be celebrated,” says Lambert. “It contains other wonderful things — vitamins, minerals, fibre, incredible polyphenols. It affects our brain health and our cells but calorie counting makes people look at food as numbers. An avocado can have higher calories than a chocolate bar but it doesn’t mean you shouldn’t eat it.”

Calories first started being talked about in relation to food in the 19th century. A chemist called Wilbur Atwater published an article entitled The Potential Energy of Food in 1887 that explained a study he did that looked at how much of the food we eat is actually absorbed into the body. The calculations he used still form the basis of calorie-counting today.

Dr. Giles Yeo, an obesity researcher at Cambridge University, is also angry about calories. So angry, in fact, he wrote a whole book about it. In Why Calories Don’t Count Dr Yeo makes the point that all calories are not created equal and that processed foods are far more “calorically available” than whole ones. “200g of crisps is not the same as 200g of carrots. Our bodies have to work harder to extract the calories from unprocessed foods. It’s the quality of the food you’re eating that is more important.”

He believes that the aim should be trying to encourage people to eat healthier rather than an obsession with calories.

“Obesity is an issue and I understand the push to provide more information but let’s be smarter about this and provide more useful, nuanced information such as amount of protein, fiber, added sugars and saturated vs unsaturated fats. A pure number tells you nothing about the nutrition of the food. If you eat healthily your weight should take care of itself.”

There’s no escaping that the UK has a problem with food. At the moment 63 per cent or two thirds of adults in the UK are overweight or obese and one in three children leave primary school overweight. A poll of 1,000 adults by Vita Mojo, whose technology powers ordering systems for over 90 UK restaurant brands including Leon and Nando’s, found that 57 per cent of diners said calories on menus would influence their choices. But Dr Yeo says calorie counts have long been on packaged food — which makes up a huge part of our diet in the UK — and the obesity crisis is still here. Besides, how often do people actually eat at restaurants? Data from Statista, from 2019, found that 40 per cent of people asked, dined out just once a month eating at home the rest of the time.

Eating disorder charity, Beat, also questions the efficacy of displaying calories as a means of getting people to lose weight. “A 2018 Cochrane review called Nutritional labeling for healthier food or non‐alcoholic drink purchasing and consumption found that there is only a small body of low-quality evidence supporting the idea that calorie counts on menus lead to a reduction in calories purchased,” said a representative from the charity. “Although a more recent study found that calorie labeling in US fast food restaurants was associated with a 4 per cent reduction in calories per order, this reduction diminished over one year of follow-up, suggesting any small differences that may occur are not maintained. ”

According to Tim Spector, professor of genetic epidemiology at King’s College London, focusing on calories is pointless anyway. “I’m not saying calories don’t exist but trying to manage your weight by estimating the calories that go into you every day and the amount you’re burning is nearly impossible. It’s really hard to estimate even if you’re a professional. Firstly you’d have to count and weigh everything you ate which most people don’t do. Then people forget extra snacks and drinks.

“We know that the calories on manufacturers labels are within a 10 per cent approximate range. And then many products are given the same calories but vary massively in the food matrix.”

He uses the example of whole and ground nuts. “Whole nuts are given the same calories as ground nuts but that’s an overestimate in the whole nut because all that energy is not available. The structure of food makes a difference to the available calories. There’s a whole list of errors that nutritionists know about but never make it to the public. It’s even worse in restaurants because the calories are complete guesses by the chain and there’s no one checking whether they’re accurate or not.”

In Spector’s view, calories on food are a smoke screen designed by the major food companies to change our minds about the food’s quality. “If you look at a packet in a supermarket and see it says it’s low in calories you think it must be good for you but actually it’s got 20 ingredients that look like you’re in some industrial chemist and has no resemblance to food.” This can lead people to eat more food because they believe it is “healthy”. “It’s a meaningless number and putting them on menus is a complete waste of time — like sticking a plaster on a massive haemorrhage. It’s an easy measure for the government to take but it’ll do nothing to help the massive obesity crisis. It’s just a pathetic distraction.”

It’s ultra-processed foods which are the real enemy, according to Spector. More than 50 per cent of the UK’s diet is now ultra-processed – in Portugal it’s only 9 per cent. This means anything with over 10 ingredients and encompasses most ready meals, biscuits, snacks. “We believe that the chemicals in these foods affect your gut microbes and trigger your brain [to make you want to eat more of them].”

Instead of focusing on calories, Spector, who’s written two books debunking beliefs about food (The Diet Myth and Spoon-Fed) says eat a diet that’s good for your gut microbes, stick to whole foods and maybe even get a personalized nutrition test like the one he runs, Zoe.

With a continuous glucose monitor, a blood fat test and gut microbiome profiling you can see how you react to certain foods. “It’ll help you pick foods that agree with your own metabolism. People can eat identical food, identical portions at the same time of day and have different reactions to each other. Some people may experience a sugar dip three hours after eating certain foods and then go on to eat 200-300 calories more over the course of the day but other people won’t. Everyone is different and that’s what the calorie ignores.”

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