Dr Giles Yeo on his new book Why Calories Don’t Count: How We Got The Science Of Weight Loss Wrong

Virgin Radio

22 Jun 2021, 12:05

The University of Cambridge geneticist joined the Chris Evans Breakfast Show with Sky to talk about the science behind calories and some welcome news about what we can eat for better health. And yes, that includes the odd chocolate bar. 

He told Chris: “The main gist of the message is that we eat food and not calories so every calorie is equal, but only once we get it into us and it's like a little poof of energy that we can use.

"But because we eat food our body then has to work to get the calories out and it has to expend energy in order to get it out and so therefore, depending on whether or not you're eating a carrot, a doughnut or a steak, your body works at different rates, uses different amounts of energy so we extract different calories for every kind of food that we actually eat.

“This has been known for a long time, people have ignored it and I'm not entirely sure why. So the calorie counts we see everywhere on the back of whatever packets we actually have are 120 years old, they come from a guy called Wilbur Atwater… but he never took into account the energy it takes… in 1900 he published it and he did a great job…

"He worked out that we don't absorb everything but then he didn't work out the energy actually taking place and it's quite significant... If you eat 100 calories of protein, you only ever absorb 70 calories.

“It doesn't matter whether it comes from a bean or it comes from a steak. It's exactly 30%. If you have 100 calories of fat, you pretty much get close to 100 calories of fat, because it's very dense, it takes no heat at all to take it apart.

"So if we're talking about sugar then for every 100 calories of sugar you eat you get 95/96 calories, so it still takes a little bit of energy. Whereas if you're having a slice of wholemeal toast, then it takes 10% so for every 100 calories of wholemeal toast you only absorb 90 calories, it costs 10 calories to sort out 100 calories of wholemeal toast."

He said about the importance of protein: "You need protein or we will become a puddle of water on the floor and we need fibre to be regular and also to keep the gut bugs happy. So these two are absolutely critical but when you look at some of the foods we’re eating today, the ultra processed foods, they're very low in protein and very low in fibre and because they have no flavour, you have to add flavour.

"And so when we're eating 400 calories of that compared to 400 calories of something else, then we're going to be absorbing completely different amounts of nutrients at different rates depending on what we're doing. So I think that's the important thing, not as a calorie counting method, but we need to improve the quality of our diets.

“The vast majority of non infectious diseases we're suffering from today is diet related. So there is a problem we need to solve - obesity, type 2 diabetes...  we want to solve it not by fearing food, not by counting every element but by improving the quality of our diet and if we do that then we go some way in order to try and fix the diet-related illnesses."

So what can we do? He advised: “We’ve got think of two things; protein and fibre. When you're looking at the back of a pack of any kind of food you want to be focusing on protein and fibre, and how much is actually there.

“If you're going out and you're actually buying a joint of meat or if you're buying vegetables I don't think you have to worry about it.

"I'm talking about the pre packaged food where we actually have to focus- but don't tell me to to replace a chocolate bar with a banana because sometimes life demands a chocolate bar.”

Why Calories Don’t Count: How We Got The Science Of Weight Loss Wrong is on shelves now.