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Beware of belly fat

By Victor Katch

(Image by Moss Greene.)

(Image by Moss Greene.)

The latest research in the field of human body composition reveals startling new findings regarding how fat in different regions of the body affect physical wellness.Evidence reveals the fat lying deep inside the abdomen, called visceral or intra-abdominal fat, threatens our health more than the fat just under the skin, called subcutaneous fat.

For most people, about 90 percent of body fat is made up of subcutaneous fat, usually located in five major body-fat depots: on the back of the arm; on the back, just below the shoulder-blade; on the hips; in the belly (abdomen); and on the top front of the legs.The remaining 10 percent, the intra-abdominal visceral fat, resides beneath the firm abdominal wall and in the spaces surrounding such internal organs as the liver, spleen, intestines, and gall bladder.

Visceral fat also locates in the omentum, an apron-like flap of tissue under the belly muscles that blankets the intestines. As the omentum fills with fat it gets hard and thick. Another visceral abdominal location is behind the organs and called retroperitoneal-visceral fat.

Visceral fat is not visible to the naked eye. Researchers locate it by using magnetic resonance imaging (MRI) to “see” inside the abdominal cavity. They use the resulting image to estimate the amount of visceral fat a person is carrying.

Increased visceral fat causes problems

Even though visceral fat comprises a small percentage of total body fat, recent research indicates it is a more significant indicator for assessing overall health than the more plentiful subcutaneous fat.

Increased visceral fat has been found to link to several chronic conditions including:

  • Increased blood pressure, leading to cardiovascular disease
  • Elevated blood cholesterol
  • Increased blood sugar
  • Dementia (A recent study of individuals in their early 40s with the highest levels of abdominal fat, compared with those who had the least abdominal fat at the same age, were nearly three times more likely to develop dementia, including Alzheimer’s disease, by their mid-70s to early 80s.)
  • Asthma (Increased belly fat is thought to raise the risk of asthma because of its inflammatory effects throughout the body, including the air passages.)
  • Colorectal cancer (Individuals with high visceral fat have three times the risk of having precancerous polyps than those with the least visceral fat.)

Subcutaneous fat serves many purposes. It produces certain beneficial hormones and serves as an important energy storehouse. While visceral fat also acts as an energy storehouse, it additionally secretes hormones and other molecules that directly increase a person’s risk of developing type 2 diabetes, coronary heart disease, and other chronic conditions.

Women between ages 35-55, in particular, see more increases in visceral belly fat than males. Even if a person doesn’t gain much weight, the waistline increases as more deposits of visceral belly fat push out against the abdominal wall.

Measure your visceral fat

While the MRI and computerized tomography (CT) represent the most accurate measurement techniques to assess visceral fat, these techniques are expensive and not available for routine use. However, substantial research shows that a person’s waist circumference represents a relatively good estimate of abdominal-visceral fat.

The waist girth is taken just above the level of the navel, not the narrowest part of the torso (sometimes referred to as the upper waist). The bottom of the tape measure needs be level with the top of the right hip bone (ilium). Don’t suck in your gut or pull the tape tight to compress the area.I advise you have someone else take the measurement to help reduce error. Have your partner take several measurements and use the average value for all calculations. It is best to take the measurement in front of a mirror to insure the tape is parallel to the ground when making the reading.

For most women, a waist circumference of 35 inches or larger, and for most men a measurement of 40 inches or larger, generally indicates a sign of excess visceral fat and associates with a higher risk for disease development. (Be aware: If your overall body size is very large or you are very tall, these cut-off values may not apply.)

The table below presents the relative degree of risk based on waist circumference in adult males and females.

Criteria for Waist Circumference in Adults
Waist Circumference in Inches
Risk Category Women Men
Very Low
Low 28.5-35.0 inches 31.5-39.0 inches
High 35.5-43.0 39.5-47.0
Very High >43.5 inches >47.0 inches
From: Bray GA. Am J. Clin. Nutr. 2004;70(3):347-9.

What to do about excess visceral fat?

According to the latest research, increased physical movement significantly reduces the amount of visceral fat you carry around. The more exercise you do, the more visceral fat you lose.

In a study comparing sedentary adults with those exercising at different intensities, researchers found that the non-exercisers experienced a nearly nine percent gain in visceral fat after six months. Subjects who exercised the equivalent of walking or jogging 12 miles per week (classified as moderate physical activity) put on no visceral fat, and those who exercised the equivalent of jogging 20 miles per week (moderate-to-vigorous physical activity) lost both visceral and subcutaneous fat!

Spot exercising, such as doing sit-ups, won’t reduce visceral fat, but it can tighten abdominal muscles, which is a good thing.
Strength training (exercising with weights) also may help fight abdominal-visceral fat. One study that followed overweight or obese women ages 24–44 for two years found those doing an hour of weight training twice a week reduced their proportion of body fat by nearly four percent—and were more successful in keeping off visceral fat—compared to participants who received advice about exercise but did not weight train.

Diet also plays an important role in reducing visceral fat. Pay attention to portion size and emphasize eating whole foods, lean protein, and complex carbohydrates (fruits, vegetables, and whole grains) instead of simple and refined carbohydrates (white bread, refined-grain pasta, and sugary drinks). Replacing saturated fats and trans fats with polyunsaturated fats also can help. But drastically cutting calories is not a good diet strategy, because it can force the body into starvation mode, slowing metabolism and paradoxically causing it to store fat more efficiently later on.

Kershaw, E.E. (2004).
“Adipose tissue as an endocrine organ,” The Journal of Clinical Endocrinology & Metabolism

Montague, C.T. (2000). “The perils of portliness: causes and consequences of visceral adiposity,” Diabetes
Irving, B. (2008). “Effect of exercise training intensity on abdominal visceral fat and body composition,” Medicine and Science in Sports and Exercise
Ismail, I. (2012). “A systematic review and meta-analysis of the effect of aerobic vs. resistance exercise training on visceral fat,” Obesity Review
Shuster, A. (2012). “The clinical importance of visceral adiposity: A critical review of methods for visceral adipose tissue analysis,” British Journal of Radiology

Victor Katch

Victor Katch

VICTOR KATCH has been active in the exercise, nutrition, and weight control arena for more than 40 years at the University of Michigan. He earned his undergraduate degrees in international relations (political science) and physical education (kinesiology) from California State University at Northridge. He also did undergraduate work in international relations at the prestigious University of Uppsala in Sweden. Katch's graduate degrees are from the University of California, Berkeley. He is a professor in movement science in the School of Kinesiology. He has three children and five grandchildren, and is an avid exerciser who enjoys year-round walking and jogging with his wife, Heather, and playing golf whenever possible, weather permitting.