Re: BMI - All Its Cracked Up To Be?
Posted: Mon May 14, 2012 10:45 am
- BMI was always intended as a research tool for interpreting populations, not small samples such as N=1.
- the reason it is inappropriate as an individual guide to overweight is because humans can be healthy outside of the healthy ranges. Asians and Polynesians have different healthy BMI ranges to Caucasians, lean tissue can be developed in someone with sub 15% body fat above healthy healthy BMI range.
- a primary contact health professional, who knows what they are doing, doesn't use BMI. BMI seems to be something people who work outside of health and read a lot of websites, get hung up on. Though admittedly, many primary health pros are not as objective or skill in communication, as their job requires.
- the reason some health pros bandy around BMI as a guide for individuals, is that it is only a very small % of the population that develops lean tissue to the extent they have a BMI outside normal range and simultaneous healthy bodyfat%.
- It also should be understood what "healthy" BMI range indicates. It doesn't mean you will have optimal health in that range. It means outside that range, you are more likely to have a higher statistical probability of developing prevalent morbidities. Some of these morbidities may not manifest for 20-40 years. This should put into context anecdotal reports about people's experience over 1-5 years.
- So BMI is not all that it is cracked up to be, by those who don't understand its limitations. If you are seeing a health pro about a weight issue, and they are guiding you with BMI, drop them, and find a health pro who uses and is competent in skinfold testing, or imaging techniques.
- if you want to understand what is and isn't healthy body fat percentage, or what is optimal for a specific sport, read up about that specifically.
- finally, understand that medical consensus re advice on this matter is heavily influenced by cultural factors. Two examples:
1. As you age, GPs in general advise carrying additional body fat is preferable, as it provides additional energy during chronic illness. However, there's no evidence older slimmer Asians have more health complications. And in fact, it's possible carrying additional fat increases the risk of getting sick more often. From my conversations with many doctors and researchers in the field, doctors are more concerned older people get adequate nutrition. Living alone, depression, presenile dementia, dehydration, and malabsorption issues, can cause malnourishment, and it's these factors more likely driving GP advice for older people to carry more fat.
2. GPs regularly see the problems of people aiming for lower bodyfat and not attaining it for the long term. They make a decision the lesser of two evils is to carry additional bodyfat. That decision might be best in the short to medium term interests of the patient, but not the long term. Interestingly, these problems are not prevalent in traditional Asian cultures. They seem a problem primarily of Western style affluence.
- the reason it is inappropriate as an individual guide to overweight is because humans can be healthy outside of the healthy ranges. Asians and Polynesians have different healthy BMI ranges to Caucasians, lean tissue can be developed in someone with sub 15% body fat above healthy healthy BMI range.
- a primary contact health professional, who knows what they are doing, doesn't use BMI. BMI seems to be something people who work outside of health and read a lot of websites, get hung up on. Though admittedly, many primary health pros are not as objective or skill in communication, as their job requires.
- the reason some health pros bandy around BMI as a guide for individuals, is that it is only a very small % of the population that develops lean tissue to the extent they have a BMI outside normal range and simultaneous healthy bodyfat%.
- It also should be understood what "healthy" BMI range indicates. It doesn't mean you will have optimal health in that range. It means outside that range, you are more likely to have a higher statistical probability of developing prevalent morbidities. Some of these morbidities may not manifest for 20-40 years. This should put into context anecdotal reports about people's experience over 1-5 years.
- So BMI is not all that it is cracked up to be, by those who don't understand its limitations. If you are seeing a health pro about a weight issue, and they are guiding you with BMI, drop them, and find a health pro who uses and is competent in skinfold testing, or imaging techniques.
- if you want to understand what is and isn't healthy body fat percentage, or what is optimal for a specific sport, read up about that specifically.
- finally, understand that medical consensus re advice on this matter is heavily influenced by cultural factors. Two examples:
1. As you age, GPs in general advise carrying additional body fat is preferable, as it provides additional energy during chronic illness. However, there's no evidence older slimmer Asians have more health complications. And in fact, it's possible carrying additional fat increases the risk of getting sick more often. From my conversations with many doctors and researchers in the field, doctors are more concerned older people get adequate nutrition. Living alone, depression, presenile dementia, dehydration, and malabsorption issues, can cause malnourishment, and it's these factors more likely driving GP advice for older people to carry more fat.
2. GPs regularly see the problems of people aiming for lower bodyfat and not attaining it for the long term. They make a decision the lesser of two evils is to carry additional bodyfat. That decision might be best in the short to medium term interests of the patient, but not the long term. Interestingly, these problems are not prevalent in traditional Asian cultures. They seem a problem primarily of Western style affluence.