By SUSAN CALLAHAN, Associate Editor and Featured Columnist
Not all fat is created equal. We humans have two basic types: white fat, which stores energy and brown fat, which expends energy and maintains a normal body temperature, a process known as thermogenesis. In fact, just keeping your body at a constant temperature is a full-time job. The workhorse in this process is brown adipose fat.
What exactly is brown fat and, more important to those of us who need to lose weight, how can you trigger its activation?
"Neither Fat Nor Flesh"
Brown fat was discovered in 1551 by the Swiss researcher Konrad Gessner when he was studying the anatomy of the marmot, a type of squirrel found in the Alps. He found a new type of tissue in the dissection which he described as “neither fat nor flesh”.
Over the ensuing 500 years, scientists have learned that this mysterious brown fat is critical to regulation of body temperature. We humans are particularly sensitive to temperature. Our bodies function optimally at 98.6 degrees Fahrenheit (37 degrees Celsius). Hypothermia begins when our body’s core reaches a temperature of 95 degrees ( 35 degrees Celsius). Note that we are usually only 2 itsy-bitsy degrees Celsius away from hypothermia.
How Much Heat Can Brown Fat Produce?
We humans can only produce heat in four ways. We produce heat when we contract our muscles. Or we can produce heat when we shiver. Or, we an eat --the process which converts food to energy (metabolism) releases heat. Or, we can produce heat using our brown fat. The German study and many others have estimated that we produce about 20% of our body’s heat from only 20 grams of this brown fat.
At full power, brown fat can produce 300 watts of heat per kilogram. All other tissues produce no more than a single watt per kilogram, according to a 2014 study from 2103 study led by Dr. Michael Symonds of the University of Nottingham in the UK. Literally, brown fat produces 300 times more heat than other cells.
Brown fat is brown because their cells contain more iron than white fat.
Brown fat is the answer to the mystery of why children can run outside in the cold and still feel warm. They have more brown fat than we adults do. We all start out as children with plenty of brown fat. What happens? Do our brown fat levels decline as we age?
Thin People Have More Brown Fat Activity
Newborn infants have a brutal transition. From the perfect, 37 degree Celsius paradise of the womb, they are thrust into the cold world outside. Newborns have very little skin fat. The only way they can generate heat is through brown fat and through shivering. Within 5 days of birth, brown fat production is triggered in newborns.
Scientists once believed that we adults had no brown fat. Only infants and hibernating animals were thought to have this special type of fat. Now, scientists estimate that women have 12.3 grams of this brown fat and men, on average, have 11.6 grams, according to a study led by Dr. Aaron Cypress of the Beth Israel Deaconess Medical Center and Harvard Medical School, among others.
Moreover, thin people have more active brown adipose fat than those who are overweight, a 2009 study from the Netherlands has found. This study from the Nutrition and Toxicology Research Institute Maastricht, examined the activity of brown fat in two groups of men. One group consisted of 10 lean men and the other consisted of 14 obese or overweight men. Both groups were then exposed to a normal temperature of 72 degrees Fahrenheit (22 degrees Centigrade) and a mild cold temperature of 61 degrees Fahrenheit (16 degrees Centigrade). They found that cold exposure triggered brown adipose fat activity in both groups of men.
But the brown fat activity in the lean mean was 4 times higher than in the overweight men.
Brown Fat Helps Fight Diabetes
In addition to helping weight loss, brown fat also has anti-diabetes properties. Brown fat is not inert blob. It is an active fat. Brown fat cells prefer oils as a fuel but they can also burn glucose (sugar) as a fuel. Animals whose brown fat cells were activated also had lower levels of diabetes and insulin resistance, several studies have found, including a 2011 study from the University Medical Center Hamburg-Eppendorf, in Hamburg, Germany.
How can you trigger the activation of brown fat? We have scoured the existing scientific evidence to identify the proven and unproven ways to trigger brown fat activation:
Place an Ice Pack on Your Waist. Placing an ice pack around your waist can trigger the production of brown fat, according to a new 2014 study. Actually, the fat is not turned into brown fat but into a “beige” fat, scientists from The University of Kentucky School of Medicine have found. Simply strapping an ice pack for 30 minutes around your the fat on your waist or thighs can start the trigger. The scientists also found that inflammation appears to inhibit the body’s ability to convert white fat to brown fat.
Standing May Activate Brown Fat. Do a simple experiment. Stand up for 15 minutes. You will notice something strange. You will begin to sweat. Why are you sweating? Simply standing does not use many muscles. You aren’t exercising or working out, yet you start to sweat. Scientists call the production of heat ---which makes you sweat ---even while you are not exercising “nonexercise activity thermogenesis” or NEAT. Scientists have not unravelled why simple standing turns or internal furnaces on so high but some theorize that it may be that standing activates our brown adipose fat. This phenomenon was first described in 2002 by Dr. James A . Levine and Dr. M.W. Vander Weg of the Mayo Clinic. The Mayo team has conducted several subsequent studies on this subject. In 2006 study from the team, they gave specific advice on how to increase your calorie burn and lose weight. Their findings followed their observation that “Obese individuals appear to exhibit an innate tendency to be seated for 2.5 hours per day more than sedentary lean counterparts”.
Apples (Ursolic Acid) Trigger Brown Fat. The substance which gives apple skins a waxy appearance is called ursolic acid. Ursolic acid increases skeletal muscle mass, hand grip strength, may have anti-diabetes properties and even triggers the activation of brown adipose fat, according to a 2012 study led by Dr. Steven Kunkel of the University of Iowa. In addition to apple peels, the herbs rosemary and thyme are rich in ursolic acid. Lesser amounts are found in hawthorne and basil as well as fruits including cranberries and bilberries and almonds.
Melatonin Is Not a Proven Brown Fat Trigger. Despite the hype over melatonin’s ability to turn white fat to brown, there is only one study that supports this conclusion. That study, from the University of Granada in Spain in 2013, found that melatonin induces white fat to become “beige fat”. However, the study was on lab rats, not humans, so we have to be careful in trying to extrapolate meaning from it. What is known, from numerous other studies, is that melatonin is produced when you sleep, and that interfering with sleep causes weight gain. So at this point, the best we can say is that you should avoid doing anything that interferes with getting a good night’s sleep, if you want to lose weight.