What is Visceral fat?
Visceral fat surrounds the organs and is connected with various diseases such as diabetes, hypertension, elevated triglycerides and the fast growing phenomenon known as metabolic syndrome.
Unlike stomach fat that is located under the skin, visceral fat proceeds as a lively endocrine organ releasing hormones that can lead to diabetes and insulin resistance.
To be diagnosed with intra-abdominal adiposity, your waist must be larger than 40 inches in men and 35 inches in women. The common apple-shaped body is greatly associated with elevated levels of visceral fat storage. Unlike subcutaneous fat which jiggles on the outside, visceral fat environs the organs and can’t be visually seen.
The causes of visceral fat are related to genetic makeup and lifestyle behavior. Our DNA determines wherever our body accumulates fat. For example, women usually store fat in their thighs while men in general store surplus fat in their stomachs.
Lifestyle related causes of visceral fat are linked to the amount of calories consumed versus the amount of calories exhausted during exercises. Surplus in calories will be stored as fat in the body which can be used for future energy. To reduce belly fat, aerobic exercise is suggested for most days for 30-60 minutes as caloric ingestion is reduced.
A recent study published in the Journal of the American Medical Association  found that a lifestyle intervention involving physical exercise and diet was resulted in clinically significant weight loss in obese study participants. After six months, participants lost 10.9 kg on average. More importantly, visceral abdominal fat, waist circumference, hepatic fat content, blood pressure, and insulin resistance were also reduced.
Visceral fat that surrounds the heart, liver, kidney, and pancreas can be is more dangerous than subcutaneous fat that we see in obese people. Some people can have dangerously high levels of fat surrounding these organs which can be seen on MRI body scanners. People who look skinny, but have high-levels of internal fat are often referred to as, “skinny fat.” 
- JAMA. 2010 Oct 27;304(16):1795-802. Epub 2010 Oct 9.
Image credit: http://cme.medscape.com/viewarticle/442813_3