A closer look at body fat: Where does it comes from, why do we need it, what are the best ways to burn it off, and where the heck does it go?
What is brown fat?
Brown fat, which is generally located in the neck, shoulders, and around collarbones, doesn't behave the same way white fat does. We are born with a bunch of it and we tend to keep it while we are children but we lose more and more of it as we age. Interestingly, studies have found that thin people are more likely to have brown fat than people who are overweight or obese, but the researchers don’t know why that is.
What is known is that 50 grams of this metabolically-active brown fat can burn 300 to 500 calories a day. That is roughly the equivalent of jogging for 30 minutes or swimming for 45.
Brown fat gets the color from its iron-rich mitochondria, and scientists believe that it behaves much more like muscle than it does like fat. Brown fat actually burns white fat for energy. So, while white fat stores energy and is associated with weight gain, brown fat is thermogenic (increases the heat in the body) and burns white fat’s energy for heat.
In a cold environment, which activates the brown fat, an average person with a healthy BMI could burn up to 250 calories per day because of brown fat. The bigger the brown fat stores, the bigger the white fat thermogenesis.
How much fat do we need?
It is important to remember that your ideal body fat percentage will be very different than your friends.
It is important to remember that your ideal body fat percentage will be very different than your friends. How much body fat we each have depends greatly on things that are beyond our control. Age, bone mass, gender, and genes play a large role in how much or how little body fat we will carry.
While carrying too much body fat is often associated with health issues like Type 2 diabetes, cardiovascular disease and even some types of cancer, carrying too little body fat can also be an issue.
The human body actually needs to have a certain percentage of body fat for it to be able to function properly. For women, 14 percent body fat seems to be the low end of healthy and for men that number can be as low as eight percent based on several epidemiological studies of the general population. Body fat percentages for optimal fitness and for athletes tend to be lower than optimal health values because excess fat may hinder physical performance and activity.
When body fat drops lower than 14 percent for women and eight percent for men, health risks increase, including everything from reproductive dysfunction (such as amenorrhea in women), chronic dehydration, sarcopenia (loss of muscle tissue), osteoporosis (loss of bone density), and potentially even organ and nerve damage.
Essential body fat is often referred to as the amount of fat considered necessary to keep your body functioning efficiently. It's stored in small amounts in your organs, muscles, bone marrow, and central nervous system. Along with your essential body fat, your body also needs storage fat. This is the adipose tissues that accumulates where we want it the least.
Fat cells store lipids for future energy needs, but it is also considered an endocrine organ, according to The Journal of Clinical Endocrinology & Metabolism. That means your fat cells are biologically active and besides adipocytes, adipose tissue contains connective tissue matrix, nerve tissue, stromovascular cells, and immune cells.
Adipose tissue not only responds to afferent signals from traditional hormone systems and the central nervous system but it also expresses and secretes factors with important endocrine functions. These factors include leptin (which control appetite), other cytokines, adiponectin (which regulates glucose and breaks down fats), complement components, plasminogen activator inhibitor-1, proteins of the renin-angiotensin system, and resistin.