CALORIE COUNTING: YOU’VE BEEN DOING IT ALL WRONG
As new rules aim to fix Britain’s obesity crisis and takeaway addiction, a Cambridge expert argues that much of the perceived wisdom is just ‘food shaming’
Q: So which of these is ultra-processed food? A: BOTH of them!
THE VAST majority of non-infectious diseases we face today are dietrelated. These include obesity and its closely associated illnesses – type 2 diabetes, high blood pressure, heart disease, and certain cancers. It’s an urgent public health priority to improve our diets and, for many of us, to lose weight.
To combat this, the Government’s latest obesity strategy includes the introduction of new food labelling regulations. From April next year, cafes, restaurants and takeaway businesses in England with 250 or more employees will be required to display the calorie information of every item of food and soft drink for sale. Advertising is also in the crosshairs, with a 9pm TV watershed and a total online ban for junk food ads.
On the face of it, a focus on reducing calories and junk food seems to make sense. The devil however is, as always, in the detail.
The provision of calories at the point of purchase does have its place, as it seems to give people pause for thought, and has been shown to nudge people towards lower calorie options. However, blindly counting calories, without acknowledging their source, makes no sense.
The important question to ask is not how many calories are in your food, but rather how many available or usable calories, through digestion and metabolism, can your body extract from this food?
The total calories in a food item is not the same as the number of calories we are able to use – not even close. If, for example, you were to eat 100 calories of sweet corn, much of that food would pass straight through your body.
If however, 100 calories of sweet corn kernels were ground into cornmeal and used to make corn tortillas or cornbread, suddenly a far greater proportion of the calories would be available for our bodies to use.
This is the concept of “caloric availability”. And where the calories come from really does matter.
One of the biggest factors that influence the availability of calories in food is protein content. A calorie of protein makes you feel fuller than a calorie of fat, than a calorie of carb, in that order. There are two main reasons for this.
FIRST, compared to fat and carbs, protein travels further down the gut before it is digested and absorbed. This results in the release of a different set of gut hormones, which signals to the brain to make you feel fuller.
Second, protein is also chemically more complex than fat or carbs, thus it actually takes more energy for the body to metabolise protein, with some of this energy given off as heat. Protein has a “caloric availability” of 70 per cent, meaning for every 100 calories of protein that makes it into the bloodstream, we are only ever able to use 70 calories.
Contrast this to the caloric availability of fat (98 per cent) and of carbs (90 to 95 per cent, depending on whether we are talking about complex or refined carbs).
This is the reason why high protein diets, including Atkins, Dukan, Keto, Carnivore, and Paleo work. Protein makes you feel full, which means you eat less, which means you lose weight. The other key component that reduces the caloric availability of food is fibre. Fibre is actually a type of carbohydrate. It comes in two forms – insoluble, which humans cannot digest, and soluble, that is fermented by our gut
bacteria. It keeps our gut, and its resident bacteria happy, which is important for good health.
Crucially, it also slows the release of sugar and other carbohydrates from food, preventing our blood sugar levels from rising too quickly after a meal.
Additionally, some of the by-products of the fermentation process enter the bloodstream and signal to the brain a feeling of fullness. This is the reason why diets that are high in fibre, including plant-based, low glycaemic index (GI) and the Mediterranean diet, work for weight loss and to improve health.
How about the online advertisement ban on “junk” foods?
Well, in October 2020, my colleagues from the Centre for Diet and Activity Research (CEDAR) at the University of Cambridge, estimated that banning unhealthy food advertising on television before the 9pm watershed meant that children in the UK would see, on average, 1.5 fewer “junk” food advertisements per day.
They calculated that removing these had the potential to reduce the number of children with obesity by 40,000 and those with overweight by a further 80,000.
However, this research only examined TV adverts; and anyone with teenage (or younger) children or grandchildren will know they hardly watch any linear TV. Most children today stream much of their video online, where the total size of the online “junk” food and drink advertising market is estimated at around £438million.
So there is good evidence that this approach would reduce the amount of junk food ads seen by kids, and hopefully eaten by kids.
But what is the definition of a “junk” food? Most of us will instinctively think of burgers, pizzas and other fast-food staples, as well as crisps, sweetened breakfast cereals, chocolate bars and other confectionery.
All of these are considered part of the most modern of phenomena, ultraprocessed foods. These are, in effect, industrial formulations that contain ingredients not commonly used, if at all, in normal restaurant or home cooking, such as artificial flavourings, colouring and stabilisers.
Yet, in high income countries, we now get more than 50 per cent of our calories from ultra-processed foods. Because the industrial processing has removed much of the flavour, it has to be added back in the form of salt, sugar and fat.
Additionally, these foods are also typically lower in protein and fibre, thus have very high caloric availability. It is not controversial to suggest that we, and particularly our children, do need to limit the consumption of such foods.
Two things, however, come to mind. First, the reason for the ubiquity of ultra-processed foods is that they are cheap to produce, and because of their long shelf-lives are easy to store and transport.
Hence this “junk food” is inexpensive and more likely to be bought and eaten by the poor. Second, it is intriguing that some ultraprocessed foods, such as plant-based “dairy” and the new generation of high-tech meat substitute products, have not only avoided being tarred by the “junk food” brush, but are actually used for virtue signalling, as if they bestowed on their users a halo of health.
One of the legions of preachy Instagram influencers might post a pleasing picture of their oat milk turmeric latte and protein ball breakfast, but would certainly not be caught dead with a plate of chicken nuggets.Yet the two foods can both be ultra processed.
I fear that the ultra-processed concept is too blunt a tool, and is currently being used as another cudgel to food shame the less privileged; whilst at the same time, the privileged in society celebrate and congratulate themselves for eating foods that are similarly processed but simply have better PR.
There is little doubt that we as a society need to make a concerted effort to eat more healthily. However, if we are to achieve this in a sustainable and equitable fashion, then we need to consider the quality of the diet, rather than just the number of calories in the food or any other judgmental descriptor.
Remember, we eat food, not calories.
‘The vast majority of non-infectious diseases we face today are diet-related’