In a recent edition of Money magazine they have a article on health and weight loss titled Slim Your Body,, Not Your Wallet. In the article they had a side graphic showing the average medical spending of people based on different BMI or Body Mass Index values.
I've reproduced the numbers in the graphic below:
I wanted to point this out since as you can see the medical costs escalate as the BMI goes up. Theres not really much difference from BMI 25 to BMI 30, its not even 10% more. From BMI 30 to BMI 35 though it goes up 42%, then from BMI 35 to BMI 40 the increase is 86% and from BMI 40 to BMI 45 the costs escalate 142%.
You may think that the cost is not a big concern to your wallet since you have health insurance. However you'll likely foot some if not all of that bill. Most people have deductibles, copay or co-insurance costs that mean they end up paying a good portion of their health care costs. You also may be made to pay extra by your employer. The article also says that currently in 2011 there are 7% of employers who charge extra for medical insurance for people with health issues like high BMI. They say that by 2012 it is projected that 33% of employers will charge extra.
What the numbers mean
BMI of 25 is the threshold for 'over weight' and BMI of 30 or more is considered obese. The wikipedia page on Obesity has different definitions of the higher BMI levels. You can use the BMI calculator to find your BMI.
A note about BMI: I don't believe that BMI alone is a perfect measure of your weight. BMI is a reasonable measure of over weight for most people but there are exceptions. You should also get a measurement of body fat or best yet the evaluation of a medical professional.