Why do we eat? Not a trick question. Apart from minor considerations about taste and sensory experiences, the plain fact of the matter is that we eat to get energy so we can do stuff (like read this blog…) and survive (i.e. not die). However, we are often encouraged to ensure that we control our energy intake, i.e. the number of calories we consume. To a large extent we rely on the calorific information displayed on the packages of the food we buy, to ensure that we don’t over-eat. Simply put, you find out how many calories are needed to maintain your particular ‘lifestyle’ (e.g. as published in government guidelines), and total up the calories for the food you consume to ensure you stay within that limit.
Easy, you might think, but what if the calorific information on your tin of lychees or whatever is incorrect, inaccurate, misleading or just plain wrong? That’s the concern now raised by Rob Dunn in his thoughtful piece entitled ‘Everything you know about calories is wrong’. And in the spirit of showcasing succinct writing (i.e. the following is definitely not plagiarism!), that article is admirably summarised by the journal’s ‘In brief’ commentary as follows: ‘Almost every packaged food today features calorie counts in its label. Most of these counts are inaccurate because they are based on a system of averages that ignores the complexity of digestion. Recent research reveals that how many calories we extract from food depends on which species we eat, how we prepare our food, which bacteria are in our gut and how much energy we use to digest different foods. Current calorie counts do not consider any of these factors. Digestion is so intricate that even if we try to improve calorie counts, we will likely never make them perfectly accurate’.
I don’t know, not only do we need to check the ingredients on our food packaging; we now also have to check the fundamental assumptions underlying the arithmetic! Clearly, food doesn’t do what it says on the tin…
[A plant-rich video presentation by Scientific American editor Ferris Jabr regarding this rather inconvenient truth is also available online – Ed.]