One could argue that our health is the product of factors that can be genetic (inherited) or environmental (including diet and activity). Body weight, for instance, will usually ultimately determined by these two major factors. There is no doubt that some people inherit more of a tendency to be heavier than others. Some people do genuinely have the ability to eat what and how much they like while maintain a rock-steady weight, while others eating the exact same diet may balloon in size.
Now, if we have inherited some tendency to being overweight or obese, that does not mean we’re destined to be overweight or obese. Usually, there’s considerable potential for controlling body weight using lifestyle related approach which include diet, exercise, and some positive psychology.
It used to be thought that there was not much we could do about our genes, however, recent discoveries in the field of epigenetics reveal that the influence genes have on our health is more malleable than previously recognised. This is a good thing, because it affords the potential for considerable control over health and wellbeing through environmental (including lifestyle) factors.
I was interested to read a recent study which explored, among other things, the genetic influence on body weight, and its relationship with a key lifestyle factor – sleep .
The study involved assessing the sleep habits and weights of hundreds of pairs of identical and non-identical twins. Studies on twins, such as this one, allow researchers to assess the ‘heritability’ of certain characteristics. What they discovered is that the heritability of body weight is not fixed, but varies according to how long individuals sleep for.
Specifically, for individuals sleeping less than 7 hours a night on average, the overall influence of genes on weight was 70 per cent. In those sleeping for 9 hours or more each night, the influence of genetic factors on weight was less than half this (32 per cent). In other words, the longer individuals slept for, the less influence genetic factors had on their weight and, we assume, the greater the potential for regulating weight through lifestyle adjustment.
Quite what it is about sleep that has this effect is not known. The author of an accompanying editorial makes the point that individuals who sleep for longer are essentially better rested, and may be in a better position to influence weight through healthy lifestyle behaviours. He also makes the point that healthy lifestyle behaviours, like not eating too big an evening meal, may in turn help sleep.
It may take time to dissect the precise relationship between sleep and body weight, but the message from this study is that getting a decent amount of sleep is likely to make body weight more controllable. Chances are, of course, that optimising sleep will give us
more control over other aspects of our health too.
I recently wrote a blog post in which I suggested a range of strategies which tend to improve sleep for those who have trouble here.
1. Watson NF, et al. Sleep duration and body mass index in twins: a gene-environment interaction. SLEEP 2012;35(5):597-603.