Christopher
Labos is a Montreal doctor (Division of Epidemiology,
Biostatistics and Occupational Health McGill University )who
writes about medicine and health issues.
A question
that often comes up is whether you can be both fat and fit.
The short answer to that question is yes. You can be both fat
and fit in the same way that you can be both blond and left
handed. Fatness and fitness denote two separate things.
Being
fat, or, more scientifically, being obese, refers to having
excess visceral fat coating your internal organs. It is widely
felt that visceral fat is more dangerous than the subcutaneous
fat that is stored in a layer under your skin.
Fitness
refers to the efficiency with which your muscles and the rest
of your body produce and use energy. A fit person can exercise
harder and longer without accumulating lactate in their muscles.
It is the accumulation of lactate that leads to muscle fatigue
and soreness.
Thus
fatness and fitness are two different concepts, and you can
certainly be fat while still being fit. However, it would be
wrong to say that the two concepts are completely unrelated
and that obesity is completely benign.
The
idea of metabolically healthy obesity has been debated for the
past decade. Obesity increases the risk of diseases like high
blood pressure, diabetes and high cholesterol. However, some
obese individuals do not have any of these issues. Thus the
question becomes: If you are obese but free from disease, is
your risk higher than that of a non-obese individual who is
also free of disease?
In
a recent study in England, researchers examined electronic health
records of 3.5 million people and categorized them according
to their body mass index. They also then categorized them according
to whether or not they had diabetes, high blood pressure or
high cholesterol. Thus, they were able to compare obese and
non-obese patients who were “metabolically healthy,”
that is, free of these three risk factors. About 15 per cent
of the population was categorized as being obese and metabolically
healthy.
Over
the course of five years, obese individuals with none of the
three risk factors were 49 per cent more likely to develop heart
disease, 7 per cent more likely to have a stroke, and 96 per
cent more likely to develop heart failure. In absolute terms
the increase in heart disease was about 1 extra case per 1,000
individuals, which seems small but is important when you consider
the population-wide implications.
However,
it is also important to note that the standard risk factors
(diabetes, hypertension and cholesterol) carried a much heavier
disease burden. Having one, two, or all three of those diseases
increased the number of cardiac events by five cases per thousand,
seven cases per thousand, and 10 cases per thousand. Of course,
we must also remember that obesity itself increases your risk
of developing these risk factors, and the metabolically healthy
person today may very well become the diabetic of tomorrow.
If this study had more than five years’ follow-up, that
likely would have been seen.
What
this study and prior research, show us is that obesity even
on its own carries a certain cardiovascular risk, but less than
diabetes, high blood pressure and cholesterol.
Some
have suggested that we should shift our focus away from weight
loss as a public health goal. There is some merit to this argument,
and it would be wrong to focus solely on a patient’s weight
as a marker of heart disease, especially as the traditional
cardiac risk factors are more important and, frankly, easier
to treat. But it would be equally wrong to suggest that obesity
is a benign condition.
There
has been a recent tendency to dismiss the rising prevalence
of obesity in our society. But when you consider the soaring
rates of childhood obesity, and that we are seeing Type 2 diabetes
in children, if we do not face this problem now, we will be
facing a potentially serious public health problem down the
road.
