Brown Fat a Possible Aid in Weight Control

​Five years ago, researchers made history with brown fat. At the same time, three separate research groups in different parts of the world discovered that also adult have brown adipose tissue. Until then it had been thought that the brown fat humans have in their infancy disappears with age. One of the research groups operated at Tuku PET Centre. Professor Pirjo Nuutila and Docent Kirsi Virtanen proofed the existence of brown fat with a biopsy from an adult.

Now brown fat is researched as a way to ease weight control and even as aid to weight loss. The brown adipose tissue differs from white fat in that it can burn excess energy from the body unlike the white fat that stores the extra energy.

– In the United States, the average weight of people aged 18–30 increases seven kilos each year. If we can activate the brown adipose tissue, it could have great implications, said Professor André Carpentier, who came to speak at the Turku PET Symposium from the Montreal Diabetes Research Center.Professors Pirjo Nuutila (left) and André Carpentier as well as Docent Kirsi Virtanen are the pioneers in the research on brown fat. The Chair of the PET Symposium, Professor Juhani Knuuti, was happy to introduce the researchers to the attendees. The four-day event, which has been organised since 1977, gathered nearly 400 researchers who use PET imaging in their work to Turku.

However, Carpentier warns against seeing brown fat as a miracle cure for obesity. Kirsi Virtanen sheds light on the situation with an example.

– If a person is 50 kilos overweight, the activation of brown fat might lead to a loss of about 2–3 kilos in a year. However, if the person can lose weight in another manner, active brown fat could help to maintain the gained weight loss, says Virtanen.

The researchers consider brown fat especially beneficial in situations where the body of a person who is attempting to lose weight starts to ”rectify” the decreased intake of energy by reducing energy consumption.

Cold, Chilli or a Pill to Activate the Brown Fat

According to the newest information, the activity of brown fat can be increased with exposure to cold, with certain foodstuffs, such as capsaicin found in chillies, and with beta 3-adrenoceptor agonist drugs. The drugs have been tested with animals but not yet with humans.

– For example, the exposure to cold does not have to be extreme. If you lower the temperature at home to 15–16 degrees, it already activates the brown adipose tissue.  Many of us could sleep in a room with only 17 degrees, said Kirsi Virtanen.

However, when lowering the temperature, it should be taken into consideration that, according to earlier studies, cold increases appetite. Carpentier emphasises that before the researchers can really recommend the activation of brown fat, its effects on the body have to be studied thoroughly.  For example, it has been discovered that blood pressure medication can decrease the activity of brown fat.

– It is nevertheless important to use blood pressure medication, stressed the Chair of the symposium, Professor Juhani Knuuti from the University of Turku, who is one of the leading researchers on cardiovascular diseases in the world

Many Mysteries Remain Unsolved

There are still many unknown factors related to brown adipose tissue. One of them is that its amount varies according to age. Infants have most brown fat, but by puberty it nearly disappears.

–  After puberty, the brown adipose tissue begins to increase again for as of yet an unknown reason, said Nuutila.

She stated that studying brown fat requires extensive and multidisciplinary research. At the moment, there are several ongoing research projects on the significance of brown fat in diabetes, other metabolic diseases and obesity.

Text and photos: Erja Hyytiäinen
Translation: Mari Ratia