Since a study came out a few years ago, based on BMI, that heavy people live longer and healthier than thinner people, many heavy people applauded the news.
Of course, that study was nonsense. Overweight people are prone to countless ailments from arthritis to heart disease to breast cancer to Alzheimer's. BMI is not a crude measure, it is a useless measure. Just one of many reasons is that anybody with decent muscle development will come out as overweight on BMI. It turned out that those "heavy but healthy" statistics were due to the number of well-developed individuals in the study which BMI rated as overweight.
In fact, it turns out that higher muscle mass correlates with reduced risk of illness and death. (Well, risk of death is 100% but they mean sooner rather than later.)
A meaningful gauge of being overweight for your build and fitness is your Body Fat percentage. The simplest way to do this is to have somebody use the body fat caliper method on you. That does not measure intra-abdominal fat deposits, but it assumes a correlation. Your doctor's nurse knows how to do that. There are other ways too. (An easier way is to study yourself naked in a mirror.)
This site has two charts, one depicting "ideal" fat percentages based on fitness, and the second based on age. As an athletic female, I like to be around 25-30%. Seems disgusting for your body to be 30% lard, doesn't it? It can be fine for a slender lady, though.
Just for fun, no ab exercises will give you 6-pack abs. Killer abs are all about fat. "Good abs" are visible in men at around 8% body fat, and in women around 12%. Those are either highly-athletic (ie well-beyond "fit" percentages) or otherwise verging on anorectic. I will not recommend any %s lower than those, even for models and ballet dancers, and, generally, feel that those %s are too low for regular fit people. 20% is fine for a regular fit male who plays sports and works out.
Below the fold, photos for comparison of men and women with varying body fat percentages.
