By Dr. Mercola
Your body fat percentage is a useful gauge to dictate metabolic health or dysfunction, with lower levels (to a point) generally associated with better health outcomes. This is referring to white fat (the kind that accumulates where you least want it).
Brown fat is most prominent in newborn animals (including human babies), where its main function is to generate body heat, helping newborns to regulate their temperatures.
Here's where it gets interesting… brown fat generates heat by burning calories, and because of this, it's being explored as a tool for weight loss, healthy metabolism, and much, much more.
Plus, newer research revealed that not only do adults have some brown fat, but it also appears to have physiological roles beyond heat generation. These roles are just now beginning to be explored…
Brown Fat May Help Regulate Blood Sugar
One of the latest studies on brown fat showed that people with higher levels have a faster metabolic rate, better blood sugar control, and higher insulin sensitivity.1 In the study, seven of the 12 participants had "high brown fat quotients" while five had low levels.
This in and of itself didn't lead to the benefits, however, as brown fat must be activated to offer results. One known way to do this is via exposure to cold temperatures. The men in the study were exposed to mildly cold temperatures for up to eight hours to activate brown fat.
Those with higher brown fat levels then showed increases in resting metabolism, insulin sensitivity, and glucose processing, with the researchers stating brown fat may function as an anti-diabetic tissue in humans. One of the study's authors noted:2
"We showed that exposure to mild cold raised whole body energy expenditure, increased glucose removal from the circulation and improved insulin sensitivity in men who have significant amounts of brown adipose tissue depots."
Failing Brown Fat May Cause Middle-Age Spread
As you get older, the thermogenic activity of brown fat is reduced, similar to what happened with mice in one revealing study published in the FASEB Journal.3 Mice that had a gene known as platelet-activating factor receptors (PAFR) knocked out became far more obese with age than the normal control mice.
The PAFR gene is responsible for inflammation and fat transfer, and it's thought that deactivating it impaired the function of brown fat, causing the mice to become quickly obese. This "failing" of brown fat is likely a key reason why there's a tendency to gain weight with age. The FASEB Journal's editor-in-chief noted:4
"A common complaint is that older people have to work twice as hard with their diets and exercise to get half of the results of younger people. Now we have a much better idea why this is the case: Our brown fat stops working as we age."
There's also a type of fat known as beige fat that is sometimes used interchangeably with brown fat. While it appears the two are similar, they also are likely to have distinct beneficial functions in your body, and these are only in the beginning stages of discovery. As reported in the journal Nature Medicine:5
"A clear question is whether brown and beige fat cells have different functions. The answer to this question is still unknown and has not been well studied. However, a recent study has suggested that fully stimulated brown and beige adipocytes… have similar thermogenic capacities.
… Aside from thermogenesis, it is highly probable that beige and brown adipocytes have other cell type–specific actions that have yet to be studied. For example, beige adipocytes may secrete certain factors that affect WAT [white adipose tissue, or white fat] function, systemic metabolism or both."
Characteristics of People with More Brown Fat
It's now thought that virtually everyone has small amounts of brown fat in their body, but certain groups of people tend to have more brown fat than others. The more brown fat, or the more activated brown fat, the better, as there are direct correlations between the activation of brown fat and metabolic measures of good health. For example:
- Slender people have more brown fat than obese people do
- Younger people have more brown fat than elderly people
- People with normal blood sugar levels have more brown fat than those with high blood sugar
Women also tend to have more brown fat than men, and people taking beta-blocker drugs to treat high blood pressure have less active brown fat. The latter is likely because catecholamines, which are hormones released as part of your body's natural "fight or flight" response, are known to activate brown fat, but beta-blockers block catecholamines, thereby suppressing the activation of beneficial brown fat.6
3 Natural Methods to Raise Your Levels of Brown (and Beige) Fat
Given all the emerging benefits of brown fat, you're probably wondering how you can get more of it.
Researchers are excited about the potential for a medical intervention that can help people develop more brown fat, but I would be cautious of any solution in a pill form. Instead, I'd suggest trying out some of the non-invasive methods that have been found to promote brown fat production and its activation.
1. Exposure to Cold
Scientists have repeatedly found that they can activate brown fat in adults by exposing them to cold temperatures. In one study, men burned more calories when cooled and lost white fat, the kind that causes obesity.7 According to the study's authors:
"…metabolism in brown fat really is increased when adult humans are exposed to cold. This boosts the possibility that calorie combustion in brown fat may be of significance for our metabolism and, correspondingly, that the absence of brown fat may increase our proneness to obesity…"
Swedish research published in 2009 also found that cold temperatures increased the activity in the subjects' brown fat regions.8 Cold-induced glucose uptake was increased by a factor of 15!
Based on animal models, researchers estimated that just 50 grams of brown fat (which is less than what most study volunteers have been found to have) could burn about 20 percent of your daily caloric intake—and more if "encouraged." Tim Ferriss, author of The Four-Hour Work Week, gave the following suggestions for putting this into practice (they range from easy to hard core):
- Place an ice pack on your upper back and upper chest for 30 minutes per day (you can do this while relaxing in front of the TV for example)
- Drinking about 500 ml of ice water each morning
- Cold showers
- Immersing yourself in ice water up to your waist for 10 minutes, three times per week. (Simply fill your tub with cold water and ice cubes)
In one mouse study, the animals converted white fat into brown fat simply by exercising. The study, published in the journal Disease Models and Mechanism,found that during exercise the animals' muscles released an enzyme called irisin, which triggered the conversion of white fat cells to brown.9
It still wasn't for certain whether this would hold true in humans… until preliminary studies presented at the 2013 annual meeting of the American Diabetes Association showed that both mice and men experienced beneficial "browning" of fat following exercise. Among men, the benefits were found after 12 weeks of training on an exercise bike. One of the researchers, a postdoctoral fellow at Joslin Diabetes Center, said:10
"Our results showed that exercise doesn't just have beneficial effects on muscle, it also affects fat… It's clear that when fat gets trained, it becomes browner and more metabolically active. We think there are factors being released into the bloodstream from the healthier fat that are working on other tissues."
Consuming melatonin stimulates the appearance of "beige" fat, which, the researchers of one study believe, may explain why melatonin helps control body weight, along with its metabolic benefits.11 Science Daily reported:12
"The study… showed that chronic administration of melatonin sensitizes the thermogenic effect of exposure to cold, heightens the thermogenic effect of exercise and, therefore, constitutes excellent therapy against obesity. The fact is that one of the key differences between 'beige fat,' which appears when administering melatonin, and 'white fat,' is that 'beige fat' cell mitochondria express levels of UCP1 protein, responsible for burning calories and generating heat."
It's also well proven that lack of sleep is linked to obesity, and if you're not getting enough sleep, there's a good chance your melatonin production is not up to par either. The disturbance to your melatonin levels caused by lack of sleep (and exposure to light during the night) may be one more reason why disturbed sleep leads to weight gain, and this could have far-reaching impacts on your health. It is probably unwise to take melatonin supplements for this effect but far better to stimulate your own melatonin production as I've discussed in many previous articles.
Heat-Shock Proteins and the Sauna Connection
Heat-shock proteins (HSPs) are used by your cells to counteract potentially harmful stimulus. Whenever a cell is exposed to an unfriendly environment, the DNA separates in certain regions and begins to read the genetic code to produce these stress proteins. HSPs are actually beneficial, helping to both prevent and repair damaged proteins. Heat-shock proteins are induced by heat, and this is one reason why sauna use is so beneficial.
However, intriguing research suggests heat-shock proteins may also be cold-induced. In one animal study, cold exposure induced the expression of HSPs in brown fat,13 the implications of which are as yet unknown. It's thought that cold-induced expression of heat-shock proteins may facilitate thermogenesis in brown fat,14 and, on a much broader scale, that exposing your body to reasonable amounts of both cold and heat stress may actually be beneficial.