Researchers have used a groundbreaking magnetic resonance imaging technique to identify and confirm the existence of brown adipose tissue in a living adult. The findings, published in The Journal of Clinical Endocrinology and Metabolism, could lead to the development of new treatments for obesity and diabetes, according to the study authors.
Brown adipose tissue (BAT), commonly referred to as brown fat, is one of the two types of fats present in humans and other mammals - the other being white adipose tissue (WAT), or white fat.
WAT is deemed the "bad" fat of the body. When we consume too many calories, the body converts them into an energy reserve in the form of white fat, leading to weight gain.
But BAT is known as the "good" fat. Its main function is to generate body heat by using energy to burn calories, therefore helping weight maintenance.
It has only been recently that scientists discovered the presence of brown fat in adults. Previously, it was only thought to exist in babies and children.
Since then, further research has suggested that people with higher levels of brown fat are generally slimmer, compared with those who have low levels. Other studies have found that exercise may turn white fat into brown fat, promoting weight loss, while more recent research indicates that shivering may be as good as exercise for producing brown fat.
Based on findings so far, researchers of this most recent study, from the Warwick Medical School and University Hospitals Coventry and Warwickshire NHS Trust, both in the UK, say there is potential to create ways of activating brown fat to boost energy expenditure and promote weight loss, but more data is needed.
MRI a 'safe and reproducible method for identifying BAT'
Pictured is a digitally enhanced axial MRI of the upper chest, as if viewed from the feet. Areas of potential brown fat are highlighted in green.
Image credit: University of Warwick
Until now, the majority of research into brown fat activity has been based upon findings from positron emission tomography (PET).
However, Dr. Thomas Barber, of the Department of Metabolic and Vascular Health at Warwick Medical School, told Medical News Today that this technique has limitations.
"The problem with PET as an imaging technique is that it is associated with exposure to ionizing radiation, and is therefore limited as a research technique," he said. "PET shows brown fat activity, and images can therefore be influenced by factors that affect brown fat activity, such as environmental temperature."
Therefore, the team turned to a novel magnetic resonance imaging (MRI) method to see if it could produce a clearer picture of brown fat in a living adult.
The MRI technique was used on a 25-year-old female with hyperparathyroidism-jaw tumor syndrome as she underwent parathyroidectomy - surgical removal of one or more parathyroid glands.
The research team found that the MRI was able to identify the presence of brown fat in the human body, regardless of whether it was active. This gives detailed insight as to where such fat can be found in adults - information the researchers say is "vital" for the development of treatments that activate brown fat deposits.
Explaining the benefits of the MRI technique further, Dr. Barber says:
"The MRI allows us to distinguish between the brown fat, and the more well-known white fat that people associate with weight gain, due to the different water-to-fat ratio of the two tissue types.
We can use the scans to highlight what we term 'regions of interest' that can help us to build a picture of where the brown fat is located."
He told us that another advantage to using MRI is that it is not associated with any exposure to ionizing radiation, making it more applicable to research studies.
The team says their study provides proof of concept that MRI is a "safe, reproducible imaging modality for human BAT," although further studies are needed to validate the method across a large group of adults.
"We hope to develop MRI as a means of accurately and reliably quantifying brown fat in humans." Dr. Barber told us.
"The clinical utility of this technique will be to assess efficacy of any future novel therapy that acts to augment brown fat quantity. This technique will also be useful though to gain further insight into human brown adipose tissue. For example, how many of us actually have brown fat."