Females’ fat in hips, buttocks and arms ‘helps protect against brain inflammation’

Females’ propensity to deposit more fat in places such as hips, buttocks and back of arms can help protect against brain inflammation, according to a new study.

Research by scientists at Augusta University found that due to so-called subcutaneous fat, females are less likely than men - who store fat around major organs - to suffer from inflammation leading to heart attack, stroke and dementia.

Scientists in the study looked at increases in the amount and location of fat tissue plus levels of sex hormones and brain inflammation in male and female mice at different time intervals as they gained weight through diet.

Like people, overweight female mice tend to have more subcutaneous fat and less visceral fat than male mice, and scientists found that subcutaneous fat loss increased brain inflammation in females.

“We need to really think more deeply about the underlying mechanisms for sex differences so that we can treat them and acknowledge the role that sex plays in different clinical outcomes,” said Alexis M. Stranahan, PhD, neuroscientist in the university’s department of neuroscience and regenerative medicine.

“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.”

By comparison, it was only after experiencing menopause that the females who did not lose subcutaneous fat but did eat a high-fat diet showed brain inflammation levels similar to the males.

They also concluded that BMI, an index which divides weight by height and is commonly used to indicate if someone is overweight or obese, is not as much of a meaningful indicator as widely understood.

A more accurate indicator of both metabolic and brain health risk caused by weight is waist to hip ratio, scientists argued.

“We can’t just say obesity. We have to start talking about where the fat is. That is the critical element here,” said Ms Stranahan.

The research was supported by the National Institutes of Health.