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A new study has shown that those who conceive in the womb during the colder months have a lower body mass index and less fat around their internal organs compared to individuals conceived during warmer seasons.
The research, published this week in the peer-reviewed journal Nature Metabolism, highlights the potential role that weather conditions play in influencing a person’s physiology throughout their life.
Today, obesity is considered one of the leading causes of death worldwide, with experts warning that more than 1 billion people last year carried very high levels of body fat.
While exercise and nutrition are the main factors affecting body fat, it appears that exposure to cold and heat also plays an important role.
A special type of fat called brown adipose tissue helps the body maintain its core temperature by generating heat, especially in cold environments and in newborn babies.
In contrast, white adipose tissue is the body’s primary energy store and also acts as a hormone secreting organ.
When temperatures drop, the body naturally stores less fat in the form of white adipose tissue than in warmer conditions.
But the research team, including Takeshi Yoneshiro from Tohoku University in Japan, says the factors that influence brown adipose tissue activity are not fully understood.
The study analyzed brown adipose tissue density, activity and heat production in 683 healthy men and women whose parents were exposed to cold or hot temperatures during conception and birth.
Of the participants, aged between 3 and 78 years, those conceived during the cold season had higher brown adipose tissue activity. This was linked to higher energy expenditure, greater heat production, lower visceral fat accumulation and lower body mass index in adulthood.
Here’s what the researchers say:
“Here, we report that individuals whose mothers conceived during cold seasons exhibited higher brown adipose tissue activity, adaptive thermogenesis, increased total daily energy expenditure, and lower body mass index and visceral fat accumulation.
The study concludes that brown adipose tissue activity is mainly influenced by the large variation in daily temperatures and lower ambient temperatures before pregnancy. “Lower ambient temperatures and larger fluctuations in daily temperatures during the period of conception are key determinants of brown adipose tissue activity,” the authors conclude.
The researchers call for further studies, including a more comprehensive set of populations, to find the mechanisms underlying this link.
They hope to determine how nutrition and other environmental factors influence this link.
