Fit Fat Index Shows True Diabetes Risk

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Overweight and inadequate fitness are - besides genetic predisposition - the greatest risk factors for type 2 diabetes. They usually occur in combination: Many overweight people do not like to move. But that is by no means always the case. A new index now describes how high the risk of diabetes is for people who do not fit into the usual grid. In addition to the fit fat ones, this also includes the slim movement grudges.

“We wanted to better understand how obesity and fitness interact,” writes study director Robert Sloan from the University of Kagoshima. To do this, they developed the “Fit Fat Index” (FFI). It is based on two different parameters - cardiovascular fitness and the ratio of hip circumference to body size (waist-to-height ratio).

The scientists applied the new index to data from more than 10,000 men between the ages of 20 and 100 who had participated in the Aerobics Center Longitudinal Study. Only data from participants who had not yet developed diabetes at the start of the study were taken into account. Underweight people were also not included.

Fitness and fat mass

At the start of the study, cardiovascular fitness was calculated for all men using the so-called maximum metabolic equivalent (METmax). For this purpose, the metabolism is determined on the basis of the oxygen consumption - first at rest, then under maximum stress. The fitter a person, the higher they can increase their metabolic rate.

To calculate the Fit Fat Index, the researchers divided the METmax by the ratio of waist size to body size. Top fit, lean men, for example, achieved an FFI of over 50 points, while corpulent, unfit men scored less than 15 points.

As expected, participants with a high FFI developed diabetes particularly rarely and vice versa. But for the majority of the participants, the new index turned out to be no more meaningful than the ratio of hip circumference to height or the METmax alone.

More precise prognosis for fat fit and lean lazy people

However, the FFI had a much more precise predictive power for those who did not fit into the current pattern of the fit slim and lazy fat. Especially for participants who were middle-aged at the start of the study, the FFI had the highest predictive power.

For example, a corpulent, unsportsmanlike 45-year-old person has a 20 percent chance of developing diabetes within 15 years. For someone of the same age with a similar statue, but who is much fitter, the risk of ten percent is only half as high. The same goes for a 45-year-old who is slim but unsportsmanlike.

The results show how effectively both weight loss and exercise influence the risk of diabetes, especially in middle age. The researchers hope that the FFI will raise awareness of how much you can do for your own health. The index could thus encourage lifestyle changes that prevent disease. (cf)

Source: Robert A Sloan: A Fit-Fat Index for Predicting Incident Diabetes in Apparently Healthy Men: A Prospective Cohort Study, PLOS One, June 24, 2016, doi.org/10.1371/journal.pone.0157703

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