Being that time of year, we thought it would be appropriate to begin our blog with a post about something that is a problem for a large number of us – Visceral Adipose Tissue (VAT), also known commonly as belly fat or beer belly. Adipose tissue is the common scientific term for fat tissue in the body, of which there are various types. One of these is visceral adipose, which is different to fat found in other parts of the body and has been studied more in recent decades due to the rise in obesity.

Fat tissue is used to store excess energy we have taken in through our diet and not expended. This generally occurs in two ways: 80% of all body fat and is stored subcutaneously (underneath the skin) in the upper thigh, buttock, back and anterior abdominal areas. Belly fat is stored in two main areas: subcutaneous (just underneath the skin) or intra-abdominal areas (inside the abdominal wall around the organs). It is this intra-abdominal fat that surrounds the organs that is called visceral adipose tissue (VAT) and is of much greater significance.

Why is VAT more dangerous for your health in comparison to other fat?

Firstly, the cells that make up VAT (belly fat) are larger than fat cells in other areas and have an increased resistance to insulin than fat cells in other parts of the body. Insulin resistance may be one of the most important factors linking VAT and increased cardiovascular risks as well as the risk of becoming diabetic.
Secondly, VAT is described in various studies as a pro-inflammatory endocrine tissue. This means that it secretes hormones and various other chemicals directly into the blood that cause inflammation. Through a communication network with other tissue, the sympathetic nervous system and brain they can influence appetite, energy balance, immunity, insulin sensitivity and more. The various proteins, chemicals and hormones released by this fat are generally detrimental to health. A summary of their effects are:

1. Increased obstruction (“clogging up”) of arteries (thrombosis, artherothrombosis)
2. General inflammation around the body due to inflammatory chemicals being released directly into the blood
3. Inflammation of the blood vessels
4. Insulin resistance (key to development of diabetes and increased cardiovascular incidents)
5. Increased cholesterol and fats in the blood
6. Higher blood pressure

What do these effects mean?

There is an increased risk of developing diabetes and metabolic syndrome (to be discussed later). It is also an independent risk factor for the development of cardiovascular disease, coronary artery disease, hypertension and stroke. Perhaps most significantly, excess VAT as measured by waist circumference is a significant predictor of mortality independently of body mass index, while VAT is a strong, independent predictor of ALL-CAUSE MORTALITY in men.

Going back to the subject of metabolic syndrome. According to the International Diabetes Federation, to have the syndrome, a person must have:

Central Obesity (excessive VAT) – defined as >37 inch waist for Caucasian men, >35.4 inch waist for South Asian men and >31.4 inch waist for Caucasian and South Asian women.

Plus any two of the following 4 factors:

1. Blood pressure ≥ 130/85
2. Diagnosed type 2 diabetes or a fasting plasma glucose ≥ 100 mg/dL
3. Raised Triglyceride (a type of fat (lipid) in your blood) level : ≥ 150 mg/dL
4. Reduced HDL (also called “good” cholesterol) cholesterol: < 40 mg/dL (1.03 mmol/L*) in males and < 50 mg/dL (1.29 mmol/L*) in females

Okay, so the bad news is, there is a lot to be observant about and I realise the timing isn’t that great with all that food you’ll all be consuming over the holiday period. The good news is there are a few practical ways you can keep on top of your belly fat and potential risks. Body Mass Index (BMI) and Waist Circumference (WC) are widely used measures of VAT. Although not perfect, done together they are seen to be fairly accurate measures of the health risks aforementioned. BMI is an important measure of obesity, used by the World Health Organisation and the National Institutes of Health. The NHS states that to identify your BMI:

Divide your weight in kilograms (kg) by your height in metres (m) Then divide the answer by your height again to get your BMI. If that is all too much, this is the link to the NHS BMI calculator, along with the scale:

http://www.nhs.uk/Tools/Pages/Healthyweightcalculator.aspx

For both sexes, a healthy BMI is between 18.5 and 25. Those over 30 are considered obese and those over 35 are severely obese. Obesity is considered such a risk to health that having a BMI over 30 has a stronger adverse effect on health than smoking and heavy drinking.

The second measure, waist circumference (WC), is a good measure together with BMI but is also good for those who are not overweight, as having a larger waist puts one at more risk of health problems than having a trim waist. Data from several studies support the notion that WC is an important predictor of diabetes, coronary heart disease, and mortality rate, independent of tests such as blood pressure, blood glucose, and lipoproteins. WC measurements should be made around a patient’s bare midriff (naval), after the patient exhales while standing without shoes and with both feet touching and arms hanging freely. WC measurements are typically taken 3 times and recorded to the nearest 0.1 cm. As above, a waist circumference of >37 inch waist for Caucasian men, >35.4 inch waist for South Asian men and >31.4 inch waist for Caucasian and South Asian women classifies people as having abdominal obesity and therefore having excessive VAT.

To summarise:

1. Measuring BMI and WC together are good indicators of ones general health
2. BMI over 30 has a stronger adverse effect on health than smoking and heavy drinking
3. When taken together, those with a BMI >30 and a WC > 35 inches – 37 inches in men, or a WC > 31.4 inches in women are at a much greater risk of developing several more serious illnesses involving the heart, stroke and/or diabetes and more.
4. A large WC without being overweight (BMI <30) is still a significant risk to health – diabetes, coronary heart disease,
   and mortality rate excess VAT as measured by waist circumference is a significant predictor of mortality independently of body mass index, while VAT is a strong, independent predictor of ALL-CAUSE MORTALITY in men

That’s enough of the doom and gloom for today, enjoy your holidays and look out for another blog post soon. We hope it wasn’t too difficult to understand and informative. The next posts will continue with this theme and include information on diets and exercise regimes to help reduce VAT. Any suggestions/questions are welcome. Until the next time.

West 12 Health

References
1. Harvard School of Public Health Obesity Prevention Source Website. Waist Size Matters. Available: http://www.hsph.harvard.edu/obesity-prevention-source/obesity-definition/abdominal-obesity/. Last accessed 23/12/2015.
2. Ibrahim MM. (2009). Subcutaneous and visceral adipose tissue: structural and functional differencesobr_623 11..18. Obesity Reviews. 11, 11-18.
3. Klein S, Allison DB, Heymsfield SB, Kelley DE, Leibel RL, Nonas C, Kahn R. (2007). Waist circumference and cardiometabolic risk: a consensus statement from Shaping America’s Health: Association for Weight Management and Obesity Prevention; NAASO, The Obesity Society; the American So. Am Journal Clin Nutr. 85 (1), 1197-1202.
4. Kuk JL, Katzmarzyk PT, Nichaman MZ, Church TS, Blair SN, Ross R. Visceral fat is an independent predictor of all-cause mortality in men. Obesity 2006; 14: 336–341.
5. Sturm, Roland and Kenneth B. Wells. The Health Risks of Obesity: Worse Than Smoking, Drinking or Poverty. Santa Monica, CA: RAND Corporation, 2002. http://www.rand.org/pubs/research_b….
6. Wang Y, Rimm EB, Stampfer MJ, Willett WC, Hu FB. Comparison of abdominal adiposity and overall obesity in predicting risk of type 2 diabetes among men. Am J Clin Nutr 2005;81(3):555–63.
7. Yusuf S, Hawken S, Ounpuu S, et al; INTERHEART Study Investigators. Obesity and the risk of myocardial infarction in 27,000 participants from 52 countries: a case-control study. Lancet 2005;366:1640–9.
8. Zhang X, Shu XO, Yang G, Li H, Cai H, Gao UT, Zheng W. Abdominal obesity and mortality in Chinese women. Arch Intern Med 2007; 167: 886–892.
9. Zimmet P, Alberti G, Shaw J. (2005). A new IDF worldwide definition of the metabolic syndrome: the rationale and the results. Diabetes Voice. 50 (3), 31

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