Counting calories is ‘virtually meaningless’ because we all digest food differently

  • 170 calories labelled on a serving of  almonds can be closer to 129 calories
  • However, calories in processed foods can  often exceed the labelling
  • This is because people digest differently  due to the type bacteria in their gut
  • Instead of reading labels for calories, a  more reliable approach to lose weight may be to  stick to raw or wholefoods  which are harder to digest

By  Nick Mcdermott, Science Reporter

PUBLISHED: 12:09 EST, 20  August 2013 |  UPDATED: 19:34 EST, 20 August 2013

Don’t rely on counting calories if you want  to lose weight, scientists warn.

Much of the nutritional data on labels is  based on outdated 19th century science.

And the way food is cooked – as well as an  individual’s metabolism – can make a  dramatic difference to how many  calories  are absorbed.

A nutritional label 

Scientists warn the number of calories on nutritional  labels can differ wildly from those we actually absorb. One reason is that many  foods simply pass through the body undigested, as we lack the tools to break  down seeds and tough fibres


A study found that instead of the 170  calories in a one ounce serving of raw almonds, only 129 calories are taken in.

In contrast, when eating processed foods such  as sugary cereals, the number of calories often exceeds the labelling.

Mice fed raw sweet potatoes lost more than  four grams of weight, while they  gained weight when given the same amount of  cooked food.

Another problem is that even if food is  cooked in the same way, each individual digests it differently thanks to the  type and abundance of bacteria in  their gut.

The obese may  have an over-abundance of  certain types of gut bacteria, making them  more efficient at absorbing  calories. Biologist Rob Dunn from North  Carolina State University said the  current system of calculating calorie labels is outdated.

Writing in the journal Scientific American,  he said: ‘In the end, we all want  to know how to make the smartest choices at  the supermarket.


A study last year found that instead of 170 calories in  a one ounce serving of raw almonds, closer to 129 calories are actually taken in  – a 25 per cent difference


Merely  counting calories based on food  labels is an overly-simplistic approach  to eating a healthy diet – one that  does not necessarily improve our  health.’

For those intent  on losing weight, instead  of reading the calories, a more reliable  approach may be to stick to raw or  whole foods which are harder to  digest.

A cheese sandwich  made with wholewheat bread  is harder to digest than one using a white  loaf. As a result, the former has 10  per cent fewer calories.

Food experts also warn that calorie labelling  has for years ignored the  energy content of fibre. This means that dieters have  been ‘unknowingly’ eating more calories than they thought in their muesli or  porridge.

As a result, an average bowl of bran cereal  contains an extra 20 calories, they claim. The calorie content of protein has  also been exaggerated by up to 20 per cent because the current system does not  take into account the extra energy used in chewing.

Young woman eating 

In contrast, when eating processed foods such as sugary  cereals, the amount of calories we receive can exceed the labelling. For those  intent on losing weight, instead of reading the calories, a more reliable  approach may be to stick to raw or wholefoods which are harder to digest, claim  scientists

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  1. Calories – food additives and the laws of unintended consequences – Yourfoodblog
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