Visceral vs Subcutaneous Fat
“Body Fat” is what most health aficionados and body sculptors loathe and try so hard to get rid of. Any food or supplement claiming to “burn fat” would receive immediate attention in today’s health and fitness culture.
There are two types of fat: subcutaneous and visceral. Subcutaneous fat is the type found just underneath the skin, which may cause dimpling and cellulite. Visceral fat, on the other hand, is located in the abdomen and surrounding vital organs. It can infiltrate the liver and other organs, streak through your muscles and even strangle your heart; and you can have it even if you appear to be thin. It is the latter, visceral, fat that is linked to everything from bad cholesterol and hypertension to diabetes, heart disease and stroke. While you can spot visceral fat if you have a protruding "beer" belly, it's not always that simple. Only a high-tech MRI (magnetic resonance imaging) can really show the body's fat composition, and researchers are finding that thin people may also have high amounts of this internal fat. They've even developed a tongue-in-cheek name for them: Tofi (Thin on the Outside, Fat on the Inside).
Over accumulation of visceral fat in the body, usually termed central obesity has been associated with glucose intolerance, abnormal fat levels in blood and hypertension, contributing to coronary heart diseases. These fat deposits tend to be unstable, releasing free fatty acids into the bloodstream which can impair insulin sensitivity of tissues (pancreas, liver, muscle) thus encouraging Type 2 Diabetes. On the contrary, subcutaneous fat contributes to increased leptin levels which help regulate appetite and increase insulin sensitivity of muscles. There has been inconclusive evidence associating subcutaneous fat with cardiovascular or metabolic diseases. However, excess subcutaneous fat is associated with lower body obesity and hence affects body image.
Body Fat in Bodybuilders
Given that visceral fat tends to have a more negative impact on our health, it is important to know the distribution of body fat. Sedentary lean individuals may have high levels of visceral fat and susceptible to its detriments whist surprisingly, active sumo wrestlers experience less health problems as the bulk of their fat is subcutaneous.
Body mass index (BMI), although used frequently does not provide an accurate measurement of body fat distribution as it cannot distinguish lean mass from fat (bodybuilders can have a high BMI but low body fat). Hence, advanced imaging techniques such as dual-energy X-ray absorptiometry (DEXA), computed tomography (CT) or magnetic resonance imaging (MRI) are preferred by medical researchers.
Diet & Exercise Tips for Fat Loss
Diet and exercise unequivocally constitute the most important determinants in losing body fat. It has been shown that in addition to diet, there are overall reductions in visceral and subcutaneous fat with resistant or aerobic exercises which also preserve lean mass and skeletal muscles.
Visceral fat tends to be burned uniformly from all regions of the body whilst subcutaneous fat is preferentially burnt from the abdominal area. Endurance training has also been found to be effectively reduce visceral fat whilst improving insulin sensitivity and lowering blood levels of fat. A 2007 systematic review1 of multiple studies found that there was a dose-response relationship between aerobic exercise and visceral fat. Or in other words, the more aerobic exercise you do, the more visceral fat that can be lost. It is important and vital for bodybuilding success to incorporate aerobic exercise into your workouts.
A low-fat diet high in unrefined carbohydrates is recommended in conjunction with regular moderate to high intensity physical exercise for roughly 45 minutes to an hour daily on most days of the week will help keep fat levels down. A restrictive diet low in calories is less effective given that they lower basal metabolic rate, putting the body in starvation mode resulting in hormonal changes which can lead to more effective fat storage when a normal diet is resumed. Low-carbohydrate diets which are gaining popularity also have little evidence to support their theory that carbohydrates encourage fat formation.
1 Ohkawara K, Tanaka S, Miyachi M, Ishikawa-Takata K, Tabata I. 'A dose-response relation between aerobic exercise and visceral fat reduction: systematic review of clinical trials'. Int J Obes (Lond). 2007 Dec;31(12):1786-97.
2 Cnop, M et al, 'The concurrent accumulation of intra-abdominal and subcutaneous fat explains the association between insulin resistance and plasma leptin concentrations' (2002) 51(4) Diabetes 1005
3 Hays, NP et al, 'Effects of an ad libitum low-fat, high-carbohydrate diet on body weight, body composition, and fat distribution in older men and women: a randomized controlled trial' (2004) 164(2) Archives of internal medicine 210
4 Lamarche, B, 'Effects of diet and physical activity on adiposity and body fat distribution: implications for the prevention of cardiovascular disease' (1993) 6(01) Nutrition Research Reviews 137
5 Montague, CT and S O'Rahilly, 'The perils of portliness: causes and consequences of visceral adiposity' (2000) 49(6) Diabetes 883
6 Nakamura, T et al, 'Contribution of visceral fat accumulation to the development of coronary artery disease in non-obese men' (1994) 107(2) Atherosclerosis 239
7 ScienceBlog, Subcutaneous vs. visceral fat : Which matters most when battling the bulge ? (2008) <http://scienceblog.com/15764/subcutaneous-vs-visceral-fat-which-matters-most-when-battling-the-bulge/>
8 Snijder, MB et al, 'What aspects of body fat are particularly hazardous and how do we measure them?' (2006) 35(1) International journal of epidemiology 83
9 www.Sixwise.com, The Two Types of Fat-Visceral and Subcutaneous-and Which Poses the Greatest Risk to You (2009) http://www.sixwise.com/newsletters/06/12/20/the_two_types_of_fat_--_visceral_and_subcutaneous_--_and_which_poses_the_greatest_risk_to_you.htm