Women who tend to collect fat around their thighs, hips and buttocks may enjoy extra protection against dementia and strokes, a study suggests.
Tests on mice indicated that subcutaneous fat – which sits under the skin and causes cellulite – protects against inflammation-related disorders, including heart disease.
Researchers found female mice with high levels of this type of fat had lower levels of brain inflammation than male rodents. But when the females were given liposuction, their inflammation levels shot up.
The experts are unsure why subcutaneous fat appears to have a protective fat, but previous research has linked it to the sex hormone estrogen, which acts as a natural anti-inflammatory.
But the study does not suggest that women should purposefully put on weight — as mountains of research show obesity can drive up the risk of chronic conditions like dementia, strokes and heart disease.
Female mice had higher deposits of subcutaneous fat, the type of fat under the skin, and they showed less evidence of brain inflammation than male mice with higher deposits of fat around their organs
Evidence is beginning to mount that not all fat is created equal, and what really counts is where you store that fat. The most dangerous type of fat is known as visceral fat, a firm internal layer that forms between the organs inside the abdomen. It is usually the cause of a beer belly and contributes to an undesirable apple body shape, which is considered the physique with the highest risk of health issues. Subcutaneous fat, on the other hand, is the wobbly type of fat that lies just under the skin and causes cellulite to form
Men are more apt to store body fat around their organs, known as visceral fat, which creates the dreaded ‘beer belly’.
The researchers behind the latest study say this is partly why men have a much higher risk for inflammation-related problems from heart attack to stroke than premenopausal women.
During the menopause, women produce less estrogen and begin to store visceral fat rather than the subcutaneous kind. After going through this transition, their risk of chronic illnesses related the inflammation then spikes.
In the latest study, published in the journal Diabetes, scientists at Augusta University in Georgia compared the impact of a high-fat diet, which is known to increase inflammation body-wide, in mice of both sexes following a surgery similar to liposuction to remove subcutaneous fat.
The researchers did nothing to directly interfere with normal estrogen levels, like removing the ovaries.
The researchers monitored how fat tissue, estrogen and brain inflammation levels changed in that time.
They found female rats with high levels of subcutaneous were at a lower risk of dangerous brain inflammation compared to males.
But at the end of the study, the reduced risk vanished when a liposuction-like procedure was performed.
Researchers – led by Dr Alexis Stranahan – found that subcutaneous fat loss increased brain inflammation in females without changing their levels of estrogen.
They reasoned that the distinctive fat patterns might be a key reason for the protection from inflammation that the female mice enjoyed before menopause.
The females’ brain inflammation looked much more like the males’, including increased levels of the hallmark inflammation promoters like the signaling protein TNF alpha in the brain.
Dr Stranahan said: ‘When we took subcutaneous fat out of the equation, all of a sudden the females’ brains start to exhibit inflammation the way that male brains do, and the females gained more visceral fat.’
Overweight female mice, much like female humans, tend to have more subcutaneous fat than visceral fat than their male counterparts.
The loss of some subcutaneous fat caused female mice to see spikes in brain inflammation similar to male mice brains.
It was only after hitting menopause – the transition in females during which menstruation stops – that the female mice who did not lose subcutaneous fat but did eat a high-fat diet showed brain inflammation levels similar to the males.
The study zoomed in on two parts of the brain to record inflammation, the hippocampus and hypothalamus.
The hippocampus plays a major role in learning and memory while the hypothalamus controls hormones and keeps the body in a balanced state known as homeostasis.
The loss of subcutaneous fat could have vastly different impacts on different parts of the brain, which should be investigated, according to Dr Stranahan.
HOW COULD SUBCUTANEOUS FAT PROTECT SOMEONE FROM DEMENTIA?
Women are more likely than men to store fat subcutaneously, or under the skin, than around the organs.
Men are more apt to store body fat around their organs, known as visceral adipose or fat, which is what leads to the dreaded ‘beer belly’.
Visceral fat puts men at higher risk of an inflammation-related issue than premenopausal women.
Male and female mice were fed high-fat diets for six months to record over time how and where they stored more fat tissue in their bodies.
The mice were then subject to a procedure similar to liposuction in order to remove some subcutaneous fat.
When researchers extracted some subcutaneous fat from female mice, they recorded an increase in brain inflammation without seeing any changes to their estrogen levels.
The distinctive fat patterns might be a key reason for the protection from inflammation that pre-menopausal mice enjoyed.