Wednesday, July 3, 2013

Assessing Type 2 Diabetes Risk by Looking at Abdominal, Hip, and Thigh Fat

It's easy to say our risk of disease and early death increases with our weight. It's also false. The truth is weight only predicts a shorter life and disease risk when at extremes (using body mass index, or BMI, to represent weight) [1,2]. People who are extremely underweight or extremely obese live shorter lives and carry greater risks of dying from heart disease or cancer. However, overweight and obese individuals have similar risks to people in the "healthy" weight range.

To calculate your BMI, click here.

Type 2 diabetes risk significantly increases when getting into the "severely obese" range [2]. Essentially, this means your quantity of body fat doesn't say much about potentially developing the disease if you fall under that range.

However, your body fat is still helpful for predicting type 2 diabetes. With many diseases, your body fat location may say all you need to know. Where you store your fat also indicates the odds that you'll develop diabetes.

The Risks with Abdominal and Thigh Fat

Abdominal fat and thigh fat both have meaning when it comes to type 2 diabetes, although both aren't negative signs.

A total of 2,964 men and women in Pittsburgh and Memphis were assessed via DXA tests, the gold standard for observing total body fat and fat location [3]. The participants also took a glucose test which indicates how efficiently the body is able to use and store glucose. These men and women were all at least 65 years old, with an average age of 73.6 years.

Out of those who fell into the diabetic category, 24% of men and 18% of women were in the "healthy" weight range, further showing that weight isn't a great predictor of disease. 

In regards to specific body fat location, inner-abdominal (visceral) fat strongly predicted the ability to store glucose. On the other hand, no relationship existed between thigh fat and any measures of diabetes.

A study of 41 men in Boston, between 41 and 76 years old, used CT scans and several glucose tests to look at the relationship between fat and diabetes risk [4]. Just like the Pittsburgh and Memphis study, inner-abdominal fat indicated the risk of diabetes. Total abdominal fat, which includes visceral fat and fat just under the skin, was also an effective predictor.

Researchers in the Boston study also found a strong connection between blood glucose and waist-to-hip ratio. Put simply, blood sugar was higher as midsections became rounder and thighs became thinner. A study of Swedish men also found the same results [5].

Overall, abdominal fat is a sign of diabetes risk. If thigh/hip fat indicates anything, it's a positive sign [6].

Researchers in Oxford reviewed 20 studies that assessed the relationship between thigh/hip fat with health markers in over 90,000 people. The studies consistently showed greater amounts of thigh/hip fat or large hip and thigh measurements are associated with healthier levels of insulin, insulin sensitivity (ability of the cells to take glucose from the blood),  and blood glucose.

Assessing Yourself

Excess abdominal fat is a sign that diabetes may exist or is in your future. If you have a lot of thigh and hip fat with little fat in your midsection, you're likely at a low risk for diabetes.

Realize that these studies have limitations. They merely identify correlations between the fat locations and diabetes. They do not indicate that abdominal fat causes diabetes, or that thigh and hip fat prevent diabetes.

If you want to assess your diabetes risk, the easiest way is to measure your waist-to-hip ratio. According to the American College of Sports Medicine, a health ratio is less than .95 for men and less than .8 for women (details for measuring are found in the link).

Researchers provided a number of reasons why health disparities exist with fat location. Visceral fat produces more pro-inflammatory proteins (adipokines), whereas hip and thigh fat produce more anti-inflammatory proteins. Thigh and hip fat also serve as a buffer, taking in fat that could be stored around organs (and ultimately interfere with organ function). Also, thigh and hip fat help the functioning of a key enzyme, lipoprotein lipase, which is involved in glucose usage.

Regardless of the cause for the associations , if your fat is mainly around your midsection, take it as a motivator for making changes to your lifestyle. If your fat in mainly found in your thighs and hips, don't be overly critical of the way that area looks: it's a positive sign.