What's the problem with counting calories?

Brain and bodyweight expert Giles Yeo says 'calories don't count'. Chris Smith asked why...

Giles - What is a calorie? A calorie is a unit of energy. It's the amount of energy it takes to raise a litre of water one degree Celsius at sea level - a food calorie at any rate. So they are all equal once they're in you as a little poof of energy. But because calories are tied up in food, and we actually eat food, not the calories themselves, our body has to work at different rates - put in different amounts of energy - in order to extract the calorie from the food. So it does matter whether or not a calorie comes from a carrot, a doughnut, or a steak.

Chris - The amount of chewing that you expend to extract the calories?

Giles - No, the energy it takes to metabolise the individual units of food. So glucose, fatty acids, amino acids, the energy it takes to actually pull apart the chemical components, is not taken into account on the side of the packets that you actually see everywhere.

Chris - And not just the half pint of cream or custard that inevitably goes with the stewed fruit or whatever.

Giles - Okay, clearly if you have 200 calories of cream it's going to be twice the amount of a hundred calories of cream. But a hundred calories of fruit is very, very different from a hundred calories of cream. So they count - calories count clearly if you're looking within a food type of scenario, butthere are gazillion diets out there which say, "you can only have 400 calories," for example, "for lunch." Well then it's going to make a difference whether or not you're eating 400 calories of sugar or 400 calories of celery. I think we worship the calorie today. I mean, this is the point. We count it, we intermittently eat it, we bat people over the head with them. Whereas I think we need to have a more nuanced view. I'll give you one example: for every 100 calories of protein that we actually eat, 30 calories - 30% - is used up in terms of just trying to take apart the protein and turn it into energy. It doesn't matter whether or not this protein comes from a bean or from a steak. So all protein calories on the side of every single pack are 30% wrong. And I just feel that people need to know that.

Chris - Is there therefore an ideal diet that we should subscribe to that actually takes this into account, or are people just wrong when they just look at calories? They take calories at face value, and basically these diets are prescriptively wrong?

Giles - The explanations for a lot of diets out there are probably wrong, but actually diets do work. The fad diets that we actually see everywhere - most of them actually work for some people at least some of the time, and any diet that results in a reduction in food intake is a diet that works. And so if we look at this caloric availability thing, my purpose is not for people to count calories more accurately, although that is obviously part of the thing. But the two elements of food that influence caloric availability to most are protein and fibre. And if you actually think about the protein content of your food and the fibre content of your food, it is actually quite a good marker of the quality of your diet. And so I guess the message is for people to not be counting the calories per se, but to think about the quality of the diet that you're actually eating. And I think that's far more important than the number, that calorie - which is very easy to see, the number is right there - than just to actually count the calorie in its absolute form.

Rob - So quality often gets conflated with cost, and that's always a balancing act when people are trying to make choices over the food they eat. Do you think it's possible to get a high quality diet for a low cost?

Giles - Yes, it is. Now I think there is a nuance here: clearly we can have a diet of lentils, we can eat dhal, and that is very cheap, but yet very, very nutritious. So undoubtedly you can do that. The problem there is it takes time to make a dhal, and you need to know how to make a dhal. So I think it is cheap, and this is the argument that a lot of middle class people - and we are all by definition here middle class people - just often throw about. "Look, people just need to learn how to cook better and they'll get good food," but you gotta have the time, you got to have sometimes to have the money, but you certainly have to have the knowledge in order to do that.