Body Mass Index - Discussion
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Health" Section
Body Mass Index (BMI) has been
found to be an important risk factor for a number of health related
problems. A person with a BMI of 25 and above is generally considered to be
overweight. A BMI over 30 indicates obesity.
Discussed here are recent
studies that indicate an increased risk of cataract, certain retinal
vascular diseases, and mortality (death) with an increased BMI. The formula
for determining the BMI is weight (pounds) divided by the square of the
height (inches), multiplied by 703.08141.
Cataract Risk
A study published in the
journal Ophthalmology indicates that BMI is an independent risk
factor for cataracts of the cortical and posterior subcapsular type.
(A Longitudinal Study of Body Mass
Index and Lens Opacities, the Framingham Studies, Hiller, Rita et al,
Ophthalmology 7/98;105:1244-1250)
The study included 714
individuals, aged 52 - 80, who had no cataract at the beginning of the
study.
The analysis controlled for age,
sex, education level, diabetes, and smoking. It found that the risk of
cataract (cortical) was significantly increased for high BMI (27.8 and
higher) and high average BMI (22 to 27.7). Women with a BMI over 30 were
twice as likely to have had cataract surgery as those with a BMI under 20.
An increasing BMI over time increased the risk of a posterior subcapsular
type of cataract.
Thus, BMI (weight) is a
modifiable risk factor for certain types of cataract development. For more
information, go to
Cataract.
Retinal Vascular Disease Risk
A study published in
Ophthalmology indicates that BMI is an independent risk factor for
certain vascular retinal problems.
(Risk Factors for Hemiretinal vein
occlusion: Comparison with risk factors for Central and Branch Retinal Vein
Occlusion, The Eye Disease Case-Control Study, Sperduto MD, RD, et al,
Ophthalmology, 5/98;105:765-771)
This study found that a higher
BMI (over 24.4) is associated with an increased risk for a retinal branch
vein occlusion. This can lead to retinal swelling, loss of vision, and
hemorrhage in the eye. Other significant risk factors included diabetes,
hypertension, and glaucoma. Increasing amounts of physical activity and
higher HDL cholesterol levels were associated with lower risk.
Thus, BMI (weight) is a
modifiable risk factor for retinal vascular disease. Go to
Eye Disorders for more information
about vascular eye problems under the diagnosis Macular Edema.
Mortality Risk
A study published in 12/93
examined BMI and death due to any cause, in men.
(Body Weight and Mortality, a 27
year follow-up of Middle-aged Men, I-Men Lee, et al., JAMA,
12/15/1993;270:2823-2828.)
Over 19,000 male alumni of
Harvard University were used for the study. Analysis was adjusted for age,
cigarette smoking, and physical activity. Subjects with early death (less
than 5 years from the start of the study) were excluded.
Increased BMI was found to be a
significant risk factor for mortality from all causes. Generally, the higher
the BMI, the more risk for death. The following chart shows the BMI range
and risk of death compared to the lowest risk:
|
BMI Range |
Risk of Death |
|
Less than 22.5 |
Lowest Risk |
|
22.5 - 23.5 |
23% increased risk
|
|
23.5 - 24.5 |
6% increased risk
|
|
24.5 - 26.0 |
27% increased risk
|
|
26.0 or more |
67% increased risk
|
Thus, body weight, cigarette
smoking, and physical activity all appear to be modifiable risk factors for
death in men from all causes.
