Human adults have very little brown fat, but we did as babies, where it helped us regulate our body temperature. Build-ups of white fat cause obesity, so finding a way to turn it into calorie-burning brown fat is thought to be one way to try to tackle the obesity problem.
This study found that higher doses of resveratrol caused the development of brown-fat-like cells within the white fat tissue of mice. The researchers hoped something like this might be possible in people. Importantly, based on mice studies only, we don't know whether resveratrol will have the same effect in people.
And drinking "plenty of red wine" will not lead you to lose weight – if anything the opposite will occur. A standard 750cl bottle of red wine contains around 570 calories, which is more than is found in two McDonald’s hamburgers.
Where did the story come from?
The study was carried out by researchers from South China Agricultural University and Washington State University in the US. Funding was provided by the National Institutes of Health, National Natural Science Foundation of China, Muscular Dystrophy Association, and the National Science Foundation. The study was published in the peer-reviewed medical journal International Journal of Obesity.
The Daily Telegraph was one of the few UK media outlets to run the story. Its headline was poor, which is frustrating as the actual reporting in the study is accurate and responsible.
The body of the article made clear that the study was in mice, advised readers to drink responsibly and even pointed out that "red wines such as merlot or cabinet sauvignon are known to contain resveratrol, but at a fraction of the levels found in grapes".
What kind of research was this?
This was an animal study looking into how to stimulate the development of brown fat deposits within white fat tissue in an effort to reduce obesity.
Mammals have two types of fat tissue involved in energy balance in the body – brown and white. In humans, brown fat is mostly found in babies where it is needed to keep the baby warm when they are unable to shiver. As we grow, most of our brown fat is replaced by white. Excessive accumulation of white fat causes obesity, which is linked to a range of diseases.
Though adults have little brown fat, it is said to have been recently discovered that white fat contains brown-fat-like cells called "beige" fat cells. Therefore it was thought that stimulating the development of these beige cells – so called "browning" - could reverse the harmful effects of excess white fat and improve health. How to stimulate the browning was the goal of this study.
Resveratrol, a natural chemical present in the skin of grapes and other berries, is one possibility. Research has suggested it can have beneficial effects upon metabolism in mammals and protect against high-fat-diet-induced obesity in mice. It has also been demonstrated to prevent fat development and enhance fat breakdown. However, whether it can stimulate brown fat cell development is unknown, so that’s what this research aimed to look into.
What did the research involve?
The study investigated whether resveratrol helped brown fat cells develop into white fat tissue or beige fat, and to look into the biology underlying the process.
The study included 12 female mice that were divided into two groups – one fed a high-fat diet, the other the same high-fat diet supplemented with resveratrol. Before and during the weeks on the diets the researchers took regular body measurements and examined respiratory function. At the end of the four weeks they examined samples of the mice’s fat tissue.
In the laboratory they specifically looked into how resveratrol influences activity of stromal vascular cells, which are a type of fat stem cell that can develop into different types of cells. They also further looked into the specific biochemical pathways behind any changes.
What were the basic results?
Overall the researchers found that resveratrol has a dose-dependent influence on the development of brown or beige fat cells from fat stem cells (stromal vascular cells) present in white fat tissue. Higher concentrations of resveratrol caused the development of brown or beige cells within white fat tissue, changes that could prevent the accumulation of further white fat.
When looking into the biochemical process, they found that activation of AMP-activated protein kinase – a key regulator of energy metabolism – was essential to the process. Specifically the alpha 1 form – AMPKα1.
How did the researchers interpret the results?
The researchers conclude that resveratrol induces brown-like (beige) fat cell formation in white fat tissue via AMPKα1 activation, suggesting its possible beneficial anti-obesity effects.
Conclusion
This animal and laboratory research has demonstrated that resveratrol can stimulate the development of brown-fat-like cells in white fat tissue. Adults have very little brown fat, though these cells are found and it is proposed that increasing their numbers could prevent the accumulation of more white fat and so tackle obesity.
The researchers here looked at the potential of resveratrol, a polyphenol chemical found in red grapes, and found that it can stimulate more of these brown-fat-like cells to develop in the white fat tissue of mice. However, it’s difficult to draw much more meaning from this.
Mouse studies can give an indication of biological processes that may also work in humans, but we are not identical. We don’t know that if we were to be given daily resveratrol we would also start developing more brown-fat-like cells in our fat tissue. Even if we did, we don’t know whether this would cause weight loss, or reverse obesity and its associated health risks.
Also, of course, though resveratrol may be found in red wine, the mice were not drinking red wine on a daily basis. As one of the lead researchers is quoted in the media, the amount of resveratrol found in wine is a fraction of that present in grapes and berries, as much of the chemical is filtered out during the wine production process. You would gain more resveratrol from eating the grapes and berries themselves than drinking wine – but that makes a much less exciting headline.
Wine is also high in calories, which may cancel out any slight theoretical benefit you may gain from trying to convert white fat to brown. A high alcohol intake is also known to be associated with many health risks both in the immediate and long term. The proven risks of drinking too much red wine probably outweigh any possible benefits from trying to convert white fat to brown fat.
Overall the study provides no evidence that drinking red wine will help you lose weight.