I found this article, it has some good points about BMI and if you are using the BMI standards to judge your risk factors you might want to read this, it's an eye-opener.
Your BMI is a number. It doesn't reveal anything about your body composition -- for example, how much muscle versus fat you have. That's why conclusions based only on BMI can be misleading, especially for the following groups:
Muscular people: Some people have high BMIs but don't have much body fat. Their muscle tissue pushes up their weight. People in the military who exercise daily might fall into this category, Atkinson says. Other examples: "A football player or a body builder who is very muscular. Their BMI shows up pretty high and yet their body fat is actually pretty low," Kahan says.
Frail or inactive people: Some people with BMIs that are in the normal range actually have lots of body fat though they may not look out of shape. Think of that as being fat on the inside.
"They have very low levels of muscle and bone -- often elderly people, those in poor shape, sometimes those who are sick. They tend to be somewhat frail. Their BMI can look in the normal range, even though they have quite a lot of body fat in comparison to their lean body mass," Kahan says. "Ultimately, they have similar risks as people who carry lots of body fat and have a high BMI."
Very inactive people who rarely exercise may be of normal weight and BMI but be "overfat," Atkinson says. "They don't have as much lean body mass as they should, and they have more fat than they should." In spite of being lean, if you have muscle and your not active and that muscle doesn't get any exercise, it can turn into fat, but you can exercise every day and you can't turn fat into muscle. once you accumulate excess fat the only way to lose it is to burn it and change your diet to avoid any more animal fat. Now, it almost impossible to avoid all fat in your diet and you shouldn't try, but you can change what you eat. Fish is a great substitute for meat and there are dozens of seafood that are low in mercury.
Ethnic differences: Major ethnic differences exist regarding BMI, but few people are aware of this fact, including some doctors, Kahan says. "It's certainly something that needs to be communicated better to the public and the health care community -- and in a way that people can do something about it."
For example, Asian Americans tend to develop health risks, including the risk of diabetes, at significantly lower BMIs than whites. According to the Joslin Diabetes Center in Boston, a healthy BMI for Asians ranges from 18.5 to 23.9, a full point lower than the standard range of 18.5 to 24.9.
For Asians, a BMI of 24 or more signals overweight, compared to the standard of 25. More strikingly, Asians are considered obese at a BMI of 27 or higher compared to the standard BMI obesity measure of 30 or higher.
Genetics plays a role in body fat, Atkinson says. Asian ethnic groups, from Japanese and Chinese to Cambodians and Indians from India, tend to lay down fat in the midsection, he says. "When they start gaining weight, they gain it first in their abdominal cavity."
People of Indian descent are at highest risk, according to Atkinson. "With a lot of Indians who come to the United States and start living the American lifestyle, their weight and BMI may not make them look fat, but they are particularly at risk," he says. "They have excess fat in their visceral cavity, in their abdominal fat, and that's associated with diabetes, hypertension, metabolic syndrome, and all those kinds of things."
"The standard definition of overweight is a BMI of 25 or above. But if you're from India, your risk of diabetes starts going up with a BMI of about 21 or 22," Atkinson says.
In contrast, many African-Americans may have high BMI measures, but no associated health risks, Kahan says. "Because African-Americans tend to have a little bit more lean body mass -- bone and muscle -- than, for example, Asian Americans, they very often have a deceptively higher BMI than other populations."
Compared to whites with the same weight and BMI, African-Americans tend to have less visceral fat and more muscle mass, Atkinson says. Therefore, an African-American person with a BMI of 28, which the standard chart defines as overweight, might be as healthy as a white person with a BMI of 25.
Age and BMI: The notion of an ideal BMI may shift with age. "People who are older probably should have a little more fat on them -- not obese, they shouldn't have a BMI of 30," Atkinson says. But, he points out, late in life, people who are "a little bit overweight" tend to have a better survival rate than leaner people. The reasons for that aren't totally clear, but it may have to do with having reserves to draw upon when fighting off an illness. However, it's hard to tell for sure since many factors affect someone's health.
I can agree with most of the arguments about BMI, just remember that BMI is only an indicator of your risk. The higher the number the more risk you have for disease. It's not an indicator of your condition. As an indicator of your risk, I think it does it's job, but you still need a physical exam to know your condition. Anyone who has a high risk for any disease and your BMI will give you that indication, should have regular check-ups by a physician.
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