Why calorie counting is flawed, scientifically

By The Gut Health Doctor Team

Dr Megan Rossi in a lab looking through a microscope

If I don’t count calories, surely I’ll gain weight?

This is one of the many diet myths I bust in ‘Eat More, Live Well‘. I get why this thought is all over the shop – the idea of balancing calories consumed versus calories out to maintain a healthy weight is the basis of many diet plans, healthy eating advice and government guidance.

But, newsflash: when it comes to eating a whole food, plant-based diet (remember that’s not necessarily plants only), you can forget about fixating on kcals and faffing with numbers, sums and percentages. Here’s why calorie counting is flawed, scientifically:

  1. Calorie counts on food packets or tracking apps are not as accurate as you might think. These are determined in a lab, in a very different process to what happens in your digestive system. Your body does not extract every last calorie from whole plant foods – almonds, for example, have been shown in studies to provide 30% fewer calories than the pack says. (Highly processed foods are different – most of the ‘digesting’ has been done for you by machines, so the calories are much more accessible.)
  2. Your body burns calories while you eat and digest your food – this is known as the ‘thermogenic effect.’ Whole foods like fruit, veg and nuts, which need chewing and breaking down, burn more calories as they go through eating and digestion – they have a higher thermogenic effect.

One study showed that around 50% fewer calories were burned in digesting a meal made up of processed foods, versus those burned after a whole food meal, despite both containing the same ‘theoretical’ calories.

Still not convinced? A review paper collating the results of 15 studies showed that simply switching to a diet with whole plants resulted in weight-loss (NOT weight-gain), without any calorie counting or portion controlling.

The takeaway

Ditch your calorie fixation. Labels are often inaccurate, as your digestive system is so much more complex than they allow for – plus, eating whole plant foods has been shown to keep you at your happy weight, with no need for restricting calories.


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