Have you ever wondered why kids can’t seem to feel the cold outside?
Well, scientists say there’s a reason why adults are often icy while wearing a sweater and youngsters are happy in shorts – even in icy conditions.
And it’s not just because they’re constantly jumping around.
Their secret? Having more brown fat – specialized fat cells designed to create heat and maintain the internal body temperature of 37°C (98.6°F).
Unlike white fat, which is abundant around the diaphragm, buttocks and chin, the brown type is invisible and compactly distributed deep down, especially around the shoulder blades, spine and kidneys.
It makes up nearly 5 percent of a newborn’s body fat, but levels gradually decline with age, making adults more vulnerable to colder temperatures.
Brown fat gets its color from being packed with iron-rich mitochondria, the cell’s powerhouses. Unlike white fat, which is an energy reserve, brown fat uses its power in the mitochondria to burn its own energy. When this fat burns, it can create heat without shivering, which is called thermogenesis. As shown in the image above, babies have more brown fat than adults
Aside from wrapping up warm in winter, our bodies also have their own methods of keeping warm. Adults shiver and brown fat also helps to create heat. But young children have more brown fat than adults, which could be why they seem warm even in winter
Brown fat gets its color from being packed with mitochondria, the cell’s powerhouses that are rich in iron.
Its counterpart, the white variety, acts as a reserve for the body’s organs to burn for energy.
But when the body is exposed to cold, starting at around 16°C, brown fat is activated – starting the engine to create heat in a scientific process called thermogenesis.
It does this by burning extra calories, breaking down blood sugar and fat molecules floating through the body.
And precisely for this reason, experts also think that it could be a secret weapon to beat the bulge.
Dr. Dayn Sellayah, an expert in cellular and organic metabolism at the University of Reading, told MailOnline that this is all thanks to a unique protein in brown fat.
By uncoupling protein 1, as it’s scientifically known, brown fat can break down glucose and fat molecules to make heat.
And where it is in the body — including the neck, shoulders, upper arms, spine, and abdomen — means it overlaps with blood vessels, which can warm up the blood, which is pumped around the entire body by the heart.
While adults rely on shivering — when muscles contract quickly to create heat and keep the body warm — babies don’t develop this mechanism until they’re six months old.
This means they rely more on brown fat to keep warm.
And levels don’t begin to drop until adulthood, which could explain why juveniles seem less susceptible to the cold.
Dr. Sellayah said: ‘Babies and young children have large amounts of brown fat.
‘This is especially necessary in the immediate postnatal period when newborns experience a sudden negative temperature gradient from the womb to the hospital ward.
“Plus, babies can’t use shivering as a defense against the cold.”
Women also have slightly more than men.
But it’s not just brown fat that keeps us warm.
The more white fat adults have — the fat that builds up when you eat more calories than you burn — the less likely they are to be cold.
This is because even white fat has some mitochondria that produce heat, according to Professor Kieran Clarke, an expert in physiological biochemistry at the University of Oxford.
Moreover, he thinks that especially ‘thin children are still cold’.
Thinner people generally have more brown fat than heavier people, according to a 2009 study in the New England Journal of Medicine.
Adults can increase their brown fat levels by exposing themselves to the cold, some experts in the field believe.
Increasing your exposure to cold temperatures allows stem cells, which can turn into many different types of cells, to form brown fat cells instead of white fat.
At least that’s according to a study published in the journal Scientific Reports in 2018.