Women tend to store fat in certain places. These are thighs, buttocks and the inside of the arms – it’s subcutaneous fat. We often try to get rid of it, but it leaves our body last. And this is not just so. According to a new study from the Medical College of Georgia of Augusta University, USA, this fat protects against brain inflammation that can lead to dementia and stroke, at least until menopause.
Men and women store their weight differently. In men, it is concentrated at the major abdominal organs – visceral obesity. It is known as more inflammatory, so the risk of inflammation-related problems increases. It’s about heart attack and stroke. After the onset of menopause in women, the risk levels out.
Fat as a protector against inflammation
When people think about protection in women, their first thought is estrogen. But we need to get beyond the kind of simplistic idea that every sex difference involves hormone differences and hormone exposure. 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. We did these experiments to try and nail down, firstly, what happens first, the hormone perturbation, the inflammation or the brain changes.
Alexis M. Stranahan, PhD, neuroscientist in the Department of Neuroscience and Regenerative Medicine at the Medical College of Georgia at Augusta University, an author of the study
According to Stranahan in the American Diabetes Association journal Diabetes, other likely factors that explain the estrogen-related differences are diet and genetics. She admits that the findings came as a surprise to her and considers them revolutionary.
Research methodology
Scientists examined the increase in the amount and location of adipose tissue, as well as levels of sex hormones and brain inflammation in male and female mice at different intervals. They were fed a high-fat diet.
Female mice store fat in the same way as females – as subcutaneous. Males – as visceral. The researchers concluded that the characteristic fat patterns may be a key reason for the protection against inflammation enjoyed by pre-menopausal females.
They found no signs of brain inflammation or insulin resistance, which also increase inflammation and can cause diabetes. Until the female mice reached menopause. At around 48 weeks, menstruation stops and the distribution of fat in females begins to shift slightly, becoming more male-like.
The scientists then compared the effects of a high-fat diet, which promotes inflammation throughout the body, in mice of both sexes after liposuction-like surgery to remove subcutaneous fat. They did nothing to directly interfere with normal estrogen levels, including removing the ovaries.
The loss increased brain inflammation in the women without changing the levels of estrogen and other sex hormones.
How subcutaneous fat reduces inflammation
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. It kind of shunted everything toward that other storage location.
Alexis M. Stranahan
The transition took place in about three months, which means several years in human time. By comparison, it wasn’t until after menopause that women who didn’t have their subcutaneous fat removed but ate high-energy foods had similar levels of brain inflammation to men, Stranahan says.
Scientists’ advice
Don’t get liposuction to continue a high-fat diet, Stranahan says.
Body Mass Index (BMI) is overrated, she adds. It simply divides weight by height and is commonly used to indicate overweight, obesity and, as a result, increased risk of a host of diseases. A more accurate indicator of both metabolic risk and potential brain health is the waist-to-hip ratio, which is also easy to calculate. This is what the founder of the School of Women’s Health, gynecologist-endocrinologist Natalia Silina, constantly emphasizes.
We can’t just say obesity. We have to start talking about where the fat is. That is the critical element here.
Alexis M. Stranahan
Stranahan has been studying the effects of obesity on the brain for several years. She is one of the first scientists to show that visceral fat contributes to brain inflammation in obese male mice. Subcutaneous fat transplantation on the contrary reduces brain inflammation.
