People conceived during colder months may end up with a lower body mass index and less fat around internal organs than those conceived in warmer seasons, a new study has found.
The research, published this week in the journal Nature Metabolism, highlights the potential role weather conditions play in influencing a person’s physiology over the course of their life.
Obesity is a leading risk factor for death today, with experts warning last year that over a billion people worldwide live with very high levels of body fat.
Although exercise and diet are key factors influencing body fat content, exposure to cold and warmth appear to play a major part as well.
A special type of fat called brown adipose tissue generates heat to help the body maintain its core temperature, especially in cold environments and in newborns.
White adipose tissue, in contrast, is the body’s primary store of energy and also serves as a hormone-secreting organ.
When temperatures drop, the body naturally stores less fat in the form of white adipose tissue than it does under hotter conditions.
The factors influencing brown adipose tissue activity are poorly understood, however, the researchers behind the study, including Takeshi Yoneshiro from Japan’s Tohoku University, say.
The research analyses brown adipose tissue density, activity and heat generation in 683 healthy men and women whose parents were exposed to cold or warm temperatures during conception and birth.
Participants, aged between three and 78, who were conceived during the cold season ended up with higher brown adipose tissue activity, linked to higher body energy expenditure, more heat generation, lower internal fat accumulation, and lower BMI into adulthood.
“Here we report that individuals whose mothers conceived during cold seasons exhibit higher brown adipose tissue activity, adaptive thermogenesis, increased daily total energy expenditure and lower body mass index and visceral fat accumulation,” researchers say.
Brown adipose tissue activity, the study concludes, is mainly influenced by a large variation in daily and lower ambient temperatures pre-conception. “Lower outdoor temperatures and greater fluctuations in daily temperatures during the fertilisation period are key determinants of brown adipose tissue activity,” it states.
The researchers call for further studies, including with a more diverse population set, to find out the underlying mechanisms behind this link.
They hope to determine how diet and other environmental factors affect this link.
