To fully understand obesity, you need to know your body fat percentage and not just your body mass index (BMI).
Your body composition is what you need to know. Your BMI would be a good starting point.
BMI looks at overall body fat, whereas body composition reveals where you are fat. Abdominal fat (visceral) is the worst kind of fat and it has been proven to spread toxins into the internal organs which leads to health problems such as heart disease and cancer.
Check out this study reported on in the Journal of the American Medical Association. Here are the basic methodologies the researchers used to compile their results and my assessment:
1) This obesity study is misleading, if you believe the numbers. It is true that you can make numbers say whatever you want them to say.
Mathematically, the numbers are correct according to the way the research was performed. But, they did not reveal the whole truth about obesity and its effects on your health.
The research claims that your chances of dying from cancer or heart disease does not increase if you carry up to 25 extra pounds. The study DID NOT consider all of the relevant factors. DON'T BELIEVE THESE RESULTS.
1) The study was based on BMI and not body composition.
2) The study accounted for total deaths instead of accounting for specific causes of death. As I just mentioned above, abdominal fat has been proven to lead to serious health problems.
3) The study was limited to death and did not examine the other problems caused by obesity. The physiological, sociological, and psychological effects of obesity have a great effect on your health.
4) The researchers didn't consider physical fitness and diet in their methodology. Fitness and diet affects everything, including how overweight or underweight we may be.
My message to you is this: It's always wise to take the safest route in any situation. Common sense tells us what "complete research" has already proven: if you are overweight and overfat, you will eventually have health problems (and other problems) which could lead to your death.