The Month You Were Conceived Can Predict Your Body Shape, According To Research
The study found that winter babies and summer babies may have very different metabolic functions.
Julia Zavalishina | Shutterstock When it comes to how your body is shaped, whether you're on the thin side or the thicker side is usually thought to be determined by your family's genes. But a new study shows that it might have more to do with whether your parents or ancestors were ectomorphs, mesomorphs or endomorphs. It could just be the luck of timing.
Research found that the month you were conceived can predict your body shape.
A study has landed on an interesting finding: Those conceived during certain types of weather seem to have more efficient metabolisms, less visceral fat, or the fat that accumulates around the organs, and lower measures of obesity like waist circumference.
The study, conducted at the University of Tokyo, focused on two groups of people, one composed of 356 men and another composed of a mix of 286 men and women of all ages, and found "modest yet significant associations" between the season in which they were conceived and metabolic function, particularly when it comes to how and where they store fat.
Babies conceived during the cold months of October to April were found to have higher brown adipose tissue.
Brown adipose tissue, or BAT, is a type of body fat that helps regulate body temperature in cold conditions. It activates just before your body begins to shiver as part of the process of thermogenesis, or heat generation.
Our bodies have a relatively small amount of BAT across the board. However, the study found that those conceived during cold months had more of it than those conceived during warm seasons. It makes sense — a fetus conceived in January is likely responding to the biofeedback from its mother who was braving the winter chill.
But BAT has other functions as well, namely, helping regulate blood sugar, a key part of the processes that dictate fat metabolism. And sure enough, the subjects in the study who had more of it showed increased energy expenditure, less visceral fat, and better metabolic health across the board.
The scientists think this may be a result of weather impacting genetic adaptation.
The observational study only found correlations, and their findings varied for different markers. For instance, subjects' BMI didn't seem to be associated with the season of their conception, even though their metabolic function and measurements like waist circumference did.
However, the findings are nonetheless in line with other studies that have found similar correlations between health incomes and the season in which a person was born, for example. And they think that it all may point to genetic adaptations that sperm and eggs make to cold weather.
The scientists theorized that this "sophisticated predictive cold adaptation" may have been passed through multiple generations as an evolutionary way of ensuring babies survive in cold climates. Research on mice has shown similar indications.
Exposing research subjects to different temperatures backed up the observational data.
To further strengthen their hypothesis, the scientists also had research subjects sit for two hours in rooms set at normal room temperature and another at a relatively chilly 66 degrees. They then measured their BAT activity after both sessions.
BAT activity was raised in all subjects after sitting in the cooler room, but for those conceived between October 17 and April 15, when temperatures in the Northern Hemisphere are cooler, it was noticeably higher than those conceived in Spring and Summer.
The scientists say more research is needed to fully understand how environmental factors, from temperature to nutrition, can encode "cellular memories" that impact conception and generations.
But it lends more evidence to suggest that parental health and exposure to environmental factors, especially for mothers, have key impacts on the health of their children and their risk of "complex, noncommunicable diseases." It seems that it may not just be all in the genes but also in the timing.
John Sundholm is a writer, editor, and video personality with 20 years of experience in media and entertainment. He covers culture, mental health, and human interest topics.
