Scientific Evidence
Epidemiologic evidence in areas like diet (where there
is large individual variation) is very weak. The examples of false associations (heart disease correlates
with sales of TV sets) are numerous.
It is only when the epidemiology is backed up by other scientific
evidence that it has impact. The
most important epidemiologic evidence in nutrition is that during the epidemic
of obesity and diabetes, almost all of the increase in calories was due to an
increase in carbohydrates. The reason this has more force than a simple
association is that carbohydrates stimulate insulin production which is known
to be an anabolic hormone. More important, however, is that whereas association
does not prove causality, the lack of association is an argument against
causality. During the obesity – diabetes epidemic fat consumption, and even saturated
fat consumption, stayed about the same. In fact, for men the absolute number of
calories of fat or saturated fat consumed by men went down. If we were starting
from scratch without prior prejudice the burden of proof would be a low-fat
diets not low carbohydrate diets.
I summarized some of the arguments with references on the two internet
sites.
