We all know that if you want to lose fat, you have to sweat it off. But what many people don’t know is that it may be easier to just freeze it off! Spring weather is approaching, so it’s about time to get your beach abs on. Take a cold shower or swim in a cold pool or ocean and you may be able to take advantage of this cutting-edge fat-burning science and be ready to put on bikini by summer.
BASICS ABOUT BROWN FAT
Due to our fattening waistlines and its deleterious effects on our health, the world of overweight research is constantly looking for ways to help you burn fat. Our warm-bloodedness is a result of that our bodies produce heat from chemical energy and muscle activity. When we are born, we don’t have much muscle to produce heat. We are naturally covered with two mechanisms. First, we have a healthy layer of “white” fat under our skin that keeps us insulated. Second, we are born with a very special kind of fat called “brown” fat (Brown Adipose Tissue or BAT) that generates heat.
BAT is a very metabolically active tissue that generates plenty of heat from chemical energy. It’s rich in proteins known as uncoupling proteins (UCPs), which release huge amounts of chemical energy without any mechanical activity as seen in muscles. Thus, this produces non-shivering heat. At birth people have white subcutaneous fat and relatively large amounts of BAT, which act as insulation and heat production respectively. The BAT is mostly located around internal organs and the carotids above the clavicle probably to warm the blood going to the brain. When we get cold, our muscles can produce heat by induction of a shivering response, or our BAT can increase energy production from fatty acids through UCPs. BAT can produce up to 300 times more energy per kilogram of tissue than most other tissues. The UCPs in BAT seem to be activated by the revved up, adrenalin infused sympathetic nervous system.
What’s amazing is that only small amounts of BAT are needed to make up a large amount of heat energy production. Only about 60 grams of BAT can produce up to 20% of daily energy expenditure. Even though exposure to the cold can stimulate the activity of BAT in people, this activity seems to decrease with induction of a shivering response. It would seem that non-shivering thermogenesis, which burns plenty of energy, is shut down when muscle starts the shivering process in order to preserve fat stores and thus insulation. Interestingly, BAT seems to be derived from a lineage of cells similar to muscle.
It’s now believed that most human bodies contain some amount of active BAT even in adulthood. Since BAT activity decreases considerably after the first year of life, it was once thought that it ceased to exist in any substantial amount into adulthood. The theoretical contributions of BAT to daily energy expenditure vary significantly. It’s thought that adults have about 60g of BAT mostly found above the clavicles, which produce 5-20% of daily energy expenditure.
It’s known that BAT decreases with age, it’s more common for women to have active BAT, and it’s inversely proportional to body mass index (the fatter you are, the less BAT you have). This may or may not make sense to you, but if you are fatter (white fat under your skin) you are probably burning less energy in BAT and tend to activate BAT less often (because of insulation and inactivity). It’s also known that adult BAT quickly responds with increased activity in acute cold exposure; we are going to discuss this more. It might appear as though some people have more BAT than others. Some people have what’s described as a beige fat where they have the typical BAT but it doesn’t have the UCP activity that active BAT has. This might be genetically determined to some extent.
It’s also noted that those with high myostatin levels also have less BAT activity. Mice in which myostatin has been removed are resistant to becoming obese and seem to have more BAT as well as larger muscles. The interaction between muscle and BAT may even be modulated by a newly found hormone produced by active muscle cells known as “irisin.” Irisin is believed to transform white fat into BAT and is considered a direct influence of muscle activity on fat burning. Research round irisin has also been feverish as it may be a future source of an “exercise pill” that boosts fat burning through BAT.
What’s also surprising is that consuming certain foods can boost the activity of your BAT. Using thermal imaging techniques, scientists can study the “thermic impact of meals,” i.e. food’s ability to stimulate the production of heat in the body. Have you ever seen a bodybuilder sweat after eating a big meal? It’s not a pretty sight. One study showed a major increase in BAT activity after consuming milk. In fact it was shown with thermal imaging nearly a one-degree Celsius rise in body temperature with drinking milk. It has been theorized that the macronutrient (protein, fat, carbohydrate) composition of a meal impacts the thermic effect of food. Studies suggest that when meals are higher in protein and lower in fat they trigger greater increases in thermic energy expenditure. Moreover, supplements containing capsaicin (or capsinoids) were shown to improve fat burning through the same thermic effect due to activation of BAT.
WHAT HAS RESEARCH DISCOVERED?
So now you are surely more aware of the value of BAT. It’s quite effective at burning off fat in your body. We can see that exercise, foods, and even supplements can activate your BAT.
And what happens when you expose yourself to the cold? Exposure to cold is well known to increase the activity of BAT to produce body heat. As we get older, the reduction in BAT means that less energy is burned for heat and less fat is accumulated for insulation. Recently, scientists have explored the possibility that lowering ambient room temperature can be used as a way for increasing the activity of BAT.
In July of 2013, a study was published in the Journal of Clinical Endocrinology and Metabolism, which examined the effect of placing participants in a room at either 19°C (66.2°F) or 24°C (75.2°F) and measuring overnight energy expenditure. They proved an increase in energy expenditure in the colder room of about 5% as well as a 10% increase in activity of BAT. Basing on the results, they concluded that reducing the temperature of a room could be an innovative way to help increase energy expenditure and consequently burn fat. This appears to be feasible in a temperature range consistent with that used in climate-controlled buildings. Your employer may lower the thermostat to cut the fat and save money.
In August of 2013 another group of Japanese researchers took this concept a step further and looked for results of exposure to cold on actual body composition. The researchers also decided to first use subjects that had low levels of BAT activity. So if you are a person who isn’t blessed with great BAT, this study may be best for you. Participants were exposed to 17°C (62.6°F) for two hours daily for six weeks; the researchers measured BAT activity, energy expenditure and body fat mass. Their results showed that exposure to cold undoubtedly increased BAT activity and cold-induced thermogenesis while decreasing body fat mass. They even added another treatment arm of supplementation with capsinoids and discovered increased cold-induced thermogenesis. Even though this study used temperatures that may be less tolerable for longer periods of time, they did show that you may get the desired effect from only a few hours of exposure.
Further research needs to be done to see if longer exposures to this temperature or shorter exposures to lower temperatures might be beneficial. Shivering is not only uncomfortable but it also appears to shut down BAT activity for augmentation of muscle activity.
AN INNOVATIVE WAY TO BURN FAT
We can conclude that BAT is beneficial to your fitness targets and we should be aiming to find ways to stimulate it. Whether it’s through workout, high protein foods, supplements, or exposure to cold, BAT is significantly powerful at burning fat.
The only thing that we should be warned about is that these cold exposure studies haven’t examined the effects of such exposure on your immune system. Also, you shouldn’t hold your breath for a magic pill to turn on your brown fat when all you need to do is stand in a room where you can see your breath.
Animal studies are being carried out where brown fat is transplanted into obese animals and it seems able to slim them down. Others have shown that the bile acid, chenodeoxycholic acid, can prevent obesity in mice by activating BAT.