In a society where excess fat anywhere on our body is considered unsightly and unhealthy, we have gone to the extreme where any fat is bad fat on our body. Unfortunately, we need to re-learn this. Not all body fat is bad, and in fact, we need to have some fat on our bodies to maintain our health.
"Fat has more functions in the body than we thought," says Rachel Whitmer, PhD, research scientist at the Kaiser Permanente Division of Research in Oakland, California.
Fat is known to have two main purposes, says Susan Fried, PhD, director of the Boston Obesity and Nutrition Research Center at Boston University and a long-time researcher in the field.
- Fat stores excess calories in a safe way so you can mobilize the fat stores when you're hungry.
- Fat releases hormones that control metabolism.
People have two types of fat tissue in their bodies: the widely reviled white fat tissue and the less familiar brown fat tissue. One of the many ill health effects of excess white fat tissue is decreased insulin sensitivity, which is a major contributor to diabetes. On the other hand, brown fat has several healthy qualities, including protection against obesity and diabetes.
Brown fat has gotten a lot of attention recently, with the discovery that it's not the worthless fat scientists had thought.
In recent studies, scientists have found that lean people tend to have more brown fat than overweight or obese people -- and that when stimulated, it can burn calories. Scientists are eyeing it as a potential obesity treatment if they can figure out a way to increase a person's brown fat or stimulate their existing brown fat.
It's known that children have more brown fat than adults, and it's what helps them keep warm. Brown fat stores decline in adults but still help with warmth. Studies have shown brown fat is more active in people in Boston in colder months, leading to the idea of sleeping in cooler rooms to burn a few more calories.
Brown fat is now thought to be more like muscle than like white fat. When activated, brown fat burns white fat.
Although leaner adults have more brown fat than heavier people, even their brown fat cells are greatly outnumbered by white fat cells. A 150-pound person might have 20 or 30 pounds of fat, but they are only going to have 2 or 3 ounces of brown fat. But that 2 ounces, if maximally stimulated, could burn off 300 to 500 calories a day -- enough to lose up to a pound in a week.
Brown fat is usually found in the front and back of the neck and upper back.
The purpose of brown fat is to burn calories to generate heat. That’s why brown fat is often referred to as the “good” fat, since it helps us burn, not store, calories. Brown fat is derived from muscle tissue and is found primarily in hibernating animals and newborns. After life as an infant, the quantity of brown fat significantly decreases. Adults who have comparatively more brown fat tend to be younger and slender and have normal blood sugar levels.
Compared to white fat, brown body fat burns through energy at an extraordinary rate. However, until recently, the proportion of brown fat in humans was thought to be quite small. Now a study at the Technical University of Munich (TUM) has shown that the quantity of brown fat in humans is three times greater than previously known.
This study also revealed that some groups of persons have an easier time activating their brown fat than others, or even have more of it in the first place. As several previous studies have already shown, women more frequently have active brown fat than men. Furthermore, brown fat does not react with the same level of activity in overweight individuals or in the elderly. However, active brown fat occurs with far greater frequency in about five percent of people than in the general population, in these people, 50% of the scans showed these active fatty tissue proportions.
The research suggested that this may point to a possible explanation for the phenomenon that some persons seem to gain weight after only one extra piece of cake, while others can gorge on sweets without gaining at all -- different body weights despite having the same diet. So far, we don't know the causes for a particular individual to have especially active brown fat.
A newly discovered factor may prove key to solving this riddle: The researchers showed for the first time that brown fat activity is affected by a variable known as creatinine clearance, which is related to renal function. "Further basic research is still needed," said one of the researchers, but one hypothesis is that there may be signaling substances that affect both brown fat and the kidneys.
People with higher levels of brown fat, or brown adipose tissue, in their bodies have better blood sugar control, higher insulin sensitivity and a better metabolism for burning fat stores. The findings suggest that, because of the brown fat's ability to better regulate blood sugar, this could be a potential medical weapon against diabetes.
"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," stated University of Texas Medical Branch's Labros Sidossis, professor of Internal Medicine, Division of Geriatric Medicine. "These results support the notion that brown adipose tissue may function as an anti-obesity and anti-diabetic tissue in humans."
"In this study we show that, when activated via mild cold exposure, brown adipose tissue can increase energy expenditure and burn calories. This is good news for overweight and obese people," stated Sidossis. "Of even greater clinical significance may be the finding that brown fat can help the body regulate blood sugar more effectively. This is great news for people with insulin resistance and diabetes and suggests that brown fat may prove to be an important anti-diabetic tissue."
White fat is much more plentiful than brown, experts agree. The job of white fat is to store energy and produce hormones that are then secreted into the bloodstream.
Small fat cells produce a "good guy" hormone called adiponectin, which makes the liver and muscles sensitive to the hormone insulin, in the process making us less susceptible to diabetes and heart disease.
When people increase their white fat, the production of adiponectin slows down or shuts down, setting them up for disease.
White fat has many purposes. It provides the largest energy reserve in the body. It’s a thermal insulator and cushion for our internal organs, and cushions during external interactions with our environment (in other words, it provides a soft landing when we fall on our behind!) It is a major endocrine organ, producing one form of estrogen as well as leptin, a hormone that helps regulate appetite and hunger. It also has receptors for insulin, growth hormone, adrenaline, and cortisol (stress hormone). So, it’s a myth that fat cells just sit there and no nothing all day long!
White fat is found, well, you know where it’s found. Just look in the mirror! In women, excess fat accumulates around the hips, thighs, buttocks and breasts until perimenopause (the 40’s), when fat is redistributed to the abdomen as well. Men tend to gather excess fat primarily in the belly region most of their lives.
An excess of white fat inside the belly (visceral fat) is associated with metabolic syndrome—a group of symptoms that signal an increased risk for heart disease, diabetes, and cancer. Location of body fat really matters! Excess white fat throughout the body is associated with an increased risk of breast, colon, esophageal, gall bladder, and pancreatic cancer. It’s also associated with sleep apnea and physical disabilities such as arthritis.
Ways to Generate Brown Fat:
- Exercising, which can convert white fat to a more metabolically active brown fat
- Getting enough high-quality sleep, as proper melatonin production influences the production of brown fat
- Exposing yourself to the cold regularly, such as exercising outdoors in the winter time or in a cold room
- Lowering the temperature in your living and working spaces.
It is highly likely that you can easily identify the amounts of white and brown fats your body has. But now that you understand the value of each and the importance of them, you can further create methods to increase the brown fat and reduce the white fat. Don’t be color blind! Brown is best for your health!