Is All Body Fat Bad for You?

Is All Body Fat Bad for You?

Fat has often become the ‘bad guy’ these days, but in the past, having extra fat was a sign of wealth! That was because those who accrued extra fat had more means to obtain a regular supply of food. In modern times, and for many in western cultures, there is excess food, and much of it is high in calories, fat and sugar. So, in this environment, we are prone to weight gain with that weight being mostly fat. And, unfortunately, alongside this fat gain has been increases in preventable chronic diseases such as heart diseases, diabetes and cancers.

Since fat gain has been connected with these chronic diseases, many have assumed that all fat is ‘bad’, but that is not true. In fact, we cannot survive without body fat. Fats make up every cell membrane and many hormones. Women need more fat to support their reproductive functions. So the reality is the disease risk related to fatness varies with the ‘location’ of that fat.

Two critical fats are: ‘subcutaneous fat’ which is located just underneath the skin, and ‘visceral fat’ which surrounds the body’s organs. Accurately measuring visceral fat requires expensive equipment such as MRI, CT and DXA. A more simple way to estimate visceral fat is using a waist circumference. While subcutaneous fat is included in this measure, most people with a high waist circumference also have higher amounts of visceral fat. A classic study by Hans (2002) illustrated the role of higher waist circumference compared to a higher BMI.

Metabolic syndrome is a condition where people have a clustering of risk factors such as high blood lipids, high blood pressure, high blood glucose and others The San Antonio Heart Study was a population-based, 8-year longitudinal study that evaluated the incidence of diabetes and cardiovascular disease among Mexican Americans and non-Hispanic whites in San Antonio, Texas. The study examined the development of metabolic syndrome in 1,968 people who did not meet the World Health Organization criteria for the metabolic syndrome at baseline..

After 8 years of follow-up, both BMI and waist circumference proved to be highly predictive of eventual development of metabolic syndrome. Only 10% of people with low BMI (<30) andlow waist circumference (waist circumference ≥ 40 inches in men or ≥35 inches in women) went on to develop metabolic syndrome 8 years later. About 20% of those with either a high BMI or a high waist circumference went on to develop metabolic syndrome. Those with botha high BMI and a high waist circumference had an even higher incidence of metabolic syndrome with over 33% developing the condition. In this study, about the same percent of people developed metabolic syndrome when overall weight was high (without higher waist circumference) as when waist circumference was high (without higher weight). We can conclude that higher waist circumference increases risk independent of overall fatness. In practice, two things should be communicated to clients: High levels of overall fatness will increase your risk of chronic diseases. Also, high levels of visceral fatness will also increase your risk, even if your overall fatness is not high. Lowering overall fatness AND visceral fatness to healthier levels is recommended.

Reference: Han TS et al. Analysis of obesity and hyperinsulinemia in the development of metabolic syndrome: San Antonio Heart Study. Obes Res. 2002;10:923-931.