Abdominal Fat

As men get older, they tend to add fat to the waist.  As was shown in the National Runners Study, even large amounts of weekly running do not stop the gradual increase of waist circumference over the years:

(Williams PT. Evidence for the incompatibility of age-neutral overweight and age-neutral physical activity standards from runners. American Journal of Clinical Nutrition 1997; 65:1391-6) (Note: the vertical axis label should be centimeters.)

So what can stop or slow this increase?  Resistance training seems to be the best exercise option.  In this study(pdf), resistance signfiicantly reduced abdominal fat - especially subcutaneous fat.  (Visceral fat is the fat surrounding internal organs, while subcutaneous fat is the "love handle" fat.)  Resistance training is also effective for women, too, with this study(pdf) showing the addition of resistance training leading to greatly reduced subcutaneous fat.

As far as diet choices, a low-glycemic diet shows the most promise for reducing abdominal fat.  There is a connection between the dietary glycemic load and visceral fat, as is shown in this study.  In fact, you can use waist circumference to predict (pdf) how insulin resistant a person is.  And finally, an expanding waist measurement over time predicts declining insulin sensitivity over time as well.