Though the genetic influence on weight gain is still under discussion, much of the research points to the link between genetic, behavioural and environmental factors. ‘Nature vs nurture’.

Genes make up part of the debate. Without the influence of the environment (which has an impact on our behaviour) it is difficult to understand why or how genes alone influence weight gain.

The environment encourages certain behaviours regardless of our somatotype (body type). We do inherit certain body/physical traits from our parents, however the determining factors on how this can be influenced lies with the environmental factors we are predisposed to and the behaviours we exhibit within these environments.

We know that gene mutations have shown links to bodyweight and human obesity. The gene harbouring the variant is known as fat mass and obesity-associated (FTO). People with the FTO variant have higher circulating levels of ghrelin (the hunger hormone) in their blood.

This means they start to feel hungry soon after eating a meal. Real time brain imaging reveals that the FTO gene variation changes the way the brain responds to ghrelin and to images of food in the regions linked with the control of eating and reward.

Together these findings explain why people with the obesity risk variant of the FTO gene eat more and prefer higher calorie foods compared with those with the low-risk version, even before they become overweight.

Convinced your weight gain is entirely down to your genes?

• Genes determine to some degree whether you will be a highly motivated individual, diligent and hard working, or whether you are likely to be de-motivated, disengaged or disinterested in self-fulfilment.
• Genes are likely to influence preference for certain foods and also your appetite.
• Genes impact on your relationship with physical activity and strenuous exercise, and how you perceive each.

If we consider the impact that these character profiles have on weight, it may well be that the behavioural impact of genes far outweighs the physiological effect. As mentioned, these are also determined by the environment so it is important to consider this as well as environmentally determined behaviour as a contributing factor to weight gain. If we control the environment, and our behaviour we can have greater influence on weight management.

Furthermore, another point to consider is somatotypes. Some have characteristics linked to susceptibility or resistance to weight gain.

• Endomorphic – more susceptible to weight gain, wider torso
• Ectomorph – more resistant to weight gain, slim
• Mesomorph – share both traits – heavy bones, broad torso