Hidden Fat Fact 2: Body Fat Below the Waist is Not as Dangerous
Visceral fat is a threat for another reason: It's highly susceptible to inflammation. "As the amount of stored fat increases, it triggers a cellular response designed to recruit immune cells," says Michael Schwartz, M.D., director of the diabetes and obesity center of excellence at the University of Washington. This leads to inflammation and can result in insulin resistance and a host of diseases associated with metabolic syndrome.
Fat below the waist behaves differently than visceral fat. "From an evolutionary standpoint, we believe that lower-body fat is intended as long-term storage. It's packed away, so it doesn't harm the rest of the body, and we use it as a last reserve," says Dr. Karpe. According to a 2010 review conducted by Dr. Karpe, below-the-belt fat produces fewer inflammatory compounds, which means less cardiovascular damage. This gives women a health advantage because they tend to store more fat in their lower bodies than men do. The fat women tend to carry on their hips? "That's one of the reasons we think women are more resistant to heart disease," Dr. Karpe says. For cutting-edge tips to lower your heart disease risk, follow these 5 New Tips to Help Your Heart.
Hidden Fat Fact 3: Body Fat is Far More Than a Calorie Storage Tank
Five or 10 years ago, researchers and physicians viewed fat merely as a storage system for energy—a soft balloon filled with calories. But they've since come to recognize it as an instrument that plays a critical role in your body's metabolic function. "Fat is the largest endocrine organ in the body," says David Piston, Ph.D., a professor of molecular physiology and biophysics at Vanderbilt University.
Even a 160-pound man with 13 percent body fat (that's a lean guy) has more than 20 pounds of fat. And that fat—or more specifically, the adipose cells that store fatty triglycerides and keep them out of the blood—is extremely important to his body's hormone regulation.
Consider leptin. This hormone is produced inside fat tissue, and without it you could theoretically eat until your stomach burst. Leptin regulates how responsive your body is to the "I'm full" signals coming from your stomach. The more fat cells you have, the more leptin you have circulating in your blood, so you'll feel full on less food. But while this important signal registers well in lean people, it seems to be ineffective in overweight people.
And that's just one of about 300 compounds coming from fat, says Dr. Karpe. Alas, not all of them are as benign as leptin. "When tissue is inflamed and overfilled with fat, it can pump out a lot of nasty stuff," he says. That "stuff" can hijack your appetite, reprogram your fat-storage mechanisms, contribute to conditions like arthritis, and drive your triglyceride levels to deadly heights.
The best way to cut inflammation? Yep, pack some physical activity into each day. Researchers at Appalachian State University recently determined that highly fit people who reported frequently engaging in moderate exercise such as cycling, swimming, or jogging had nearly 50 percent less C-reactive protein, a marker for inflammation, in their blood than people who were unfit and rarely exercised. (For a fast plan that works, try the Ultimate Fat-loss Workout. It's the new cutting-edge fitness system that melts fat, torches calories, and sculpts every muscle on your body.)
Hidden Fat Fact 4: Visceral Fat Undermines Your Manhood
There's a concrete connection between testosterone and visceral fat, and it works in two ways, says Farid Saad, Ph.D., head of scientific affairs for Men's Healthcare at Bayer Pharma in Berlin, Germany.
First, inadequate testosterone levels direct muscle cells to turn into (or "differentiate" into) fat, and second, visceral fat produces substances that suppress testosterone production. So as the visceral bulge grows in your belly, testosterone drops, and your body is less likely to grow muscle. If the spiral goes unchecked, you can end up overweight with no motivation to change. "Men with testosterone deficiency are also quite low on energy," says Saad. "You can tell them a thousand times to exercise, and they won't do it."
According to Saad, short-term testosterone supplements may be a viable solution. A 2012 study published in the Journal of the American Medical Association, for instance, found that men who received 20 weeks of testosterone supplementation gained fat-free, lean mass. "For men with deficiencies, 1 or 2 years of supplementation might completely break the cycle," says Saad. (Don't let this happen to you! Protect your sperm and hormones—that's What More Testosterone Can Do For You.)
Hidden Fat Fact 5: Skinny People are Not Immune
Low body fat is a pretty good indicator of health, but a dangerous clump of fat can still hide behind a flat belly. In a study published in Nature Genetics last year, researchers discovered a gene that causes those with it to carry less body fat than those without it. Surprisingly, though, people with that gene (especially men) had a higher ratio of visceral fat to subcutaneous fat. They also had higher triglycerides and lower HDL cholesterol—a risky combo that can contribute to heart disease.