Conception during the cold season lowers the risk of developing obesity, says a new study. 

Published in Nature Metabolism on April 7, the study found that people conceived in winter show more brown adipose tissue (BAT) activity, often known as brown fat, which burns calories to produce heat unlike white fat that stores energy.  

“Individuals whose mothers conceived during cold seasons exhibit higher BAT activity, adaptive thermogenesis, increased daily total energy expenditure and lower body mass index and visceral fat accumulation,” the study noted. 

Researchers in Japan looked at data from hundreds of healthy adults, examining their BAT activity and energy expenditure. They found that those born when outside temperatures were lower had more active BAT, which caused higher daily total energy expenditure.

There were two groups in the study. 

In the first cohort, researchers evaluated BAT activity in 356 young men using advanced imaging technologies They discovered that “BAT prevalence was significantly higher in those conceived in the cold season (78.2%) than in those conceived in the warm season (66.0%).”

A second cohort of 286 men and women aged 20-78 also showed similar results. Researchers used near-infrared time-resolved spectroscopy (NIR-TRS) to estimate BAT density and found a “significant increase” in BAT density in the group conceived during colder months.

Magic of winter

Additional study showed that this early-life cold exposure could be advantageous in the long run. Using structural equation modelling, the researchers discovered that “conception during the cold season protects against age-associated increase in body mass index through BAT activation in offspring.” Put differently, people conceived in colder months were less likely to put on weight as they grew older because of their more active brown fat.

But it’s crucial to keep in mind that lifestyle choices and genetics also have a big impact on weight control. These results, however, imply that early environmental exposures may affect our health in a permanent way.

The authors conclude: “These findings provide comprehensive evidence suggesting that thermal stress experienced just before conception plays an intergenerational role in facilitating the activation and sustenance of BAT and modulating systemic energy homeostasis in humans.”

Also read: How Pregnancy Changes Your Brain & Impacts Mental Health