Obesity increases the risk of developing high blood pressure and heart disease
True. The prevalence of high blood pressure (hypertension) among obese
people is greater than
in the population at large. Consuming more kilojoules than we actually need for our level of
activity can increase blood pressure; consuming less can lower blood pressure. The extent of
these
effects varies from person to person. Both energy imbalance (either an excess or deficiency of
kilojoules in relation to needs) and over-fatness, even when one is in energy balance (kilojoule
intake and needs are equal), contribute to hypertension. Overeating may contribute to high
blood
pressure in other ways. For example, as food (energy) intake increases, it is likely that more
salt
(sodium) or alcohol will be consumed.
'Burning' excess kilojoules with increased exercise can improve blood pressure control.
Obesity
can increase the risk of coronary heart disease in several ways:
- the excess fat itself can increase the work of the heart and the thickness of the heart
muscle. In this situation coronary blood may not reach all heart muscle equally well;
- by increasing blood pressure;
- by raising blood fats (cholesterol and triglyceride) and lowering a form of serum
cholesterol that is protective against heart disease (high density lipoprotein cholesterol or
HDL cholesterol; see WHAT WE KNOW
ABOUT FATS AND OILS IN FOOD);
- by decreasing the body's ability to use glucose, so requiring increased serum insulin
levels
and increasing the risk of diabetes. Diabetes itself increases the risk of hardening the
arteries.
The distribution of body fat is also important. Fat around the abdomen increases the risk
of heart
disease, strokes, diabetes and total mortality more than fat around the hips. What can we do
about
it? In general, if we decrease our total body fat with exercise and diet, fat around our 'middle'
will
also decrease. Abdominal exercise may reduce abdominal fat, but this needs confirmation.
People
generally think alcohol contributes to abdominal fatness, but curiously this has not been the
subject of scientific studies. If it does contribute, then this may account for some of the
connections between alcohol, high blood pressure and stroke.
Having said all of this, the increased health risk associated with obesity appears to be less
after the
age of 50 than before it.
