Why calorie counting can be so inaccurate

You’ll be glad to hear calorie counting is outdated. So why do we continue to use it as a guide to healthy eating?

Well, it’s simple.

A number is very easy to assess, count and act on. Also, it’s ­entrenched. The calorie has been the energy-measuring index to calculate the energy in food since 1887.

And shortly after that the idea arose that if calories in exceeded calories out, the result would be weight gain.

We’re discovering the calorie is an imperfect tool.

Firstly the calorie content in food labels is universally inaccurate. The calorie count on a UK label for a particular food is different in Australia. Most calorie values on food labels are 20% out.

Then again two items of food with identical calorific values may be digested in different ways. Each person’s body handles calories ­differently.

The time of day we eat matters. How well we sleep is another factor that affects how we burn ­calories.

A calorie is not always just a calorie. Calories from proteins, fats and carbs are handled ­differently by the body, which expends differing amounts of energy to digest them.

The weight we want to lose depends on factors other than calorie intake.

Our genes, the bacteria in our gut, food preparation and sleep all shape how much fat we store. And we absorb calories at different rates.

The body absorbs the sugar from a can of fizzy drink at a rate of 30 ­calories a minute, compared with two calories a minute from complex carbohydrates such as potatoes or rice.

That matters, because a sudden hit of sugar prompts the rapid release of insulin, a hormone that carries the sugar out of the ­bloodstream and into the body’s cells, and excess sugar is stored in fat cells.

Complex carbohydrates such as cereals on the other hand release their energy slowly, so your blood-sugar levels remain steadier.

Some people’s intestines are 50% longer than others: those with shorter ones absorb fewer calories, which means that they excrete more of the energy in food, putting on less weight.

Even when you eat and sleep can be as important as what you eat.

Going without a full night’s sleep drives your body to create more fat. And you may put on more weight eating small amounts over 12-15 hours than eating the same food in three sessions.

Sugar calories do the most damage. They lead to high insulin levels which means more energy is converted into fat leaving less available to fuel the body, driving hunger and overeating.