SEX in winter is a great way to save on heating bills without freezing your bum off.

But now there is another reason why you should jump in on the action.

Parents who conceive during winter are more likely to produce skinny children, according to findings published in Nature Medicine.

That’s compared to babies created in the summer who may face a greater chance of a lifelong battle of the bulge.

Scientists have linked cold weather conception to larger amounts of brown adipose tissue (BAT) in both mice and humans.

Only small amounts of the calorie-burning brown fat are found in human adults, mainly under the tongue, around the collar bone and along the spine.

Unlike white fat, which is linked to illness including heart disease and cancer, BAT burns calories by generating heat.

“Taken together, our results indicate that in humans and in mice, seasonal or experimental CE induces an epigenetic programming of the sperm such that the offspring harbour hyperactive BAT and an improved adaptation to overnutrition and hypothermia,” the study concluded.

Swiss scientists analysed CT scans of 8400 adults and compared those conceived during the cooler months to those born in the warmer months.

They found the first group had a greater amount of brown fat than the second lot.

Professor Christian Wolfrum at Zurich’s ETH university who led the research said that previous research has found that people in cold regions have particularly high levels of BAT.

Professor Wolfrum said: “Until now, the assumption was that this had something to do with the temperatures people experienced during their lifetime.

“But our observations suggest that temperatures prior to conception might also affect later levels of brown fat.”

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