EVER felt like being overweight wasn’t your fault?
A new study adds weight to the idea that it’s not, and comes down to your birthday.


Scientists have long disregarded astrology as ‘pseudoscience’ – the idea that aspects of your personality can be determined by the day and month you are born.
But now they say that the month you are born may influence your health, at least.
The study, by researchers at Tohoku University Graduate School of Medicine, looked at the weather and atmosphere at the time of conception (when the baby is made).
They discovered that people conceived in colder months have more active brown fat – the special type that burns calories to keep you warm.
This means higher energy use and potentially a lower body mass index (BMI) and dangerous fat around internal organs.
The coldest months are usually December, January and February.
Therefore, if you are born in September, October or November, you are most likely to benefit from the brown-fat advantage.
On the flip side, July and August – the warmest months – lead to birthdays in April and May, when this fat-burning edge is less likely.
Previous studies have linked the time of year people are born to their overall health.
One piece of research, published in Elsevier in 2015 found those born in summer are more likely to be heavier at birth and taller as adults than those born in the cooler months.
The new study, published in Nature Metabolism this month, looked at 622 men and women between the ages of three and 78.
[bc_video account_id=”5067014667001″ application_id=”” aspect_ratio=”16:9″ autoplay=”” caption=”Sun Club’s exclusive interview with Gemma Collins about her weight loss journey ” embed=”in-page” experience_id=”” height=”100%” language_detection=”” max_height=”360px” max_width=”640px” min_width=”0px” mute=”” padding_top=”56%” picture_in_picture=”” player_id=”default” playlist_id=”” playsinline=”” sizing=”responsive” video_id=”6369097991112″ video_ids=”” width=”640px”]They were grouped based on whether they were conceived in cooler months – between October 17 and April 15 – or warmer ones, from April 16 to October 16.
Those created in the colder period showed higher brown fat activity. So what does this mean?
Brown fat, known as brown adipose tissue (BAT), plays a crucial role in generating heat and regulating body temperature.
It’s not the same as white fat, which determines if we are overweight or obese.
[boxout headline=”How your birthday ‘determines your weight'”]Month of conception I Birthday I If you benefit from more brown fat yes or no
- January I October I Yes
- February I November I Yes
- March I December I Unclear
- April I January I Unclear
- May I February I Unclear
- June I March I No
- July I April I No
- August I May I No
- September I June I Unclear
- October I July I Unclear
- November I August I Unclear
- December I September I Yes
Adults have small amounts of brown fat in the neck, around the collar bone, back and a few other places too, but newborn babies have a lot more as they rely on it to maintain body temperature.
Brown fat is known to be activated by cold exposure. For example, it’s suggested that ice plunges mkes brown fat more active and therefore helps metabolism.
Crucially, parents who were exposed to greater temperature swings and lower averages just before conception seemed to pass this benefit on.
The team said brown fat activity appears to be “preprogrammed” by exposure to cold before fertilisation – and interestingly, it may be dad’s exposure that’s key.
Earlier research hinted that cold weather can leave a kind of molecular “imprint” on sperm, which influences the embryo’s metabolism and ability to handle colder climates.
Commenting on the study Raffaele Teperino, from the German Research Center for Environmental Health, said: “Parental health during conception and gestation can affect offspring development and health.

“A study in humans now shows that adult individuals who were conceived during cold seasons exhibit greater brown adipose tissue activity, increased energy expenditure, lower body mass index and lower visceral fat accumulation
“The new findings emphasise once more the critical role of the preconception environment in shaping offspring metabolism and offer perspectives for understanding the co-existence of two global health challenges – obesity and warming.”
Obesity rates rising
It comes as obesity rates are expected to soar in the UK by 2050.
Scientists predict that without urgent action, six in ten adults and a third of youngsters worldwide will be overweight or obese in 25 years.
In the UK, the total will rocket to 49million from 38.4million in 2021, sparking fears of increased pressure on hospitals and medical facilities.
Obesity currently costs the NHS around £6.5billion per year and that is projected to increase considerably as more cases need to be treated.