If you drool with envy as a skinny friend digs into chips and chocolate and never gains a pound, it could be as unfair as it seems: they may have a gene which allows them to eat fat and not gain weight, according to research published in the Journal of Molecular Medicine.

Previously we may have explained such people’s ability to remain slim as the result of a more active lifestyle, but Jose Ordovas, of Tufts University in Boston, has found that 13 per cent of us appear to have a variant of a gene (known as a “single nucleotide polymorphism” or SNP) which means that dietary fat is not associated with a higher body mass index (BMI) or risk of obesity.

“For most people in this study, eating more fat was related to a higher BMI. However, for people with a specific SNP, fat intake was not significantly related to BMI,” he explains. “These results were true despite a person’s age, sex, physical activity or the amount of calories consumed.”

However, before you weep into your low-fat breakfast cereal over the unfairness of it all, there is one drawback for this special group: if they do manage to gain weight, it may be even harder for them to shift it, compared to the rest of us.

Moreover, the interaction between the specific SNP and dietary fat was strongest for monounsaturated fats like those found in olive oil, rather than the saturated fats found in many cakes, biscuits, puddings and pies. This means that, should naturally skinny people abuse their “slim genes” by constantly wolfing down the latter foodstuffs, they may well fall into the obesity trap, not to mention clogging their arteries and ending up with heart disease.

This means that the bottom line is the same for all of us, regardless of our genetic makeup: we must eat a well-balanced diet to maintain an appropriate weight and good all-round, long term health.

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