A new study recently revealed that in winter the people evolve to have subconscious urges to over-eat and limited ability to avoid obesity.
Researchers from the University of Exeter said there is not yet an evolutionary mechanism to help the people overcome the lure of sweet, fatty and unhealthy food and avoid becoming overweight for understandable and sensible reasons.
They added this is because in past being overweight has not posed a significant threat to survival compared to the dangers of being underweight. The urge to maintain body fat is even stronger in winter when food in the natural world is scarce. This explains why the people enjoy eating so much at Christmas.
Researchers used computer modelling to predict how much fat animals should store, by assuming that natural selection gives animals, including humans, a perfect strategy to maintain the healthiest weight.
Lead author Dr Andrew Higginson said that one would expect evolution to have given them the ability to realise when they have eaten enough, but instead they show little control when faced with artificial food because modern food today has so much sugar and flavour the urge humans have to eat it is greater than any weak evolutionary mechanism which would tell us not to.
He added their model also predicts that animals should gain weight when food is harder to find. All animals, including humans, should show seasonal effects on the urge to gain weight. Storing fat is an insurance against the risk of failing to find food, which for pre-industrial humans was most likely in winter.
The study is published in the journal Proceedings of the Royal Society B.