WOMEN 'S HEALTH AND MENOPAUSE : - National Heart, Lung ...

fied as overweight or obese. 32 The cardiovascular
health burden of obesity includes a strong predisposition
to both type 2 diabetes and to hypertension.
The prevalence of these conditions in the
presence of obesity is increased by twelvefold and
fivefold respectively, in women younger than 55
years. 32 Although there remains no causal evidence
for the relationship between a sedentary lifestyle
and obesity, the association between the two factors
is strong. 33 In a female twin study, twins discordant
for intensity of physical activity displayed
significant differences in total and central body
fat. 34 In that study, physical activity was the
strongest predictor of total body fat, even after
accounting for age, diet, smoking, and HRT. In an
18-month randomized behavioral study of sedentary
obese women, there was a dose response
effect of exercise duration on weight loss. 35 Women
who were given access to home exercise equipment
showed the greatest weight
loss and maintained significantly
greater exercise duration at the
completion of the trial. HRT
decreased central abdominal fat in a
small prospective study of obese
women with type 2 diabetes. 36
Diabetes mellitus
is an important
risk factor for
CVD in women.
Obesity in women is a complex metabolic disorder
with strong genetic components. The peroxisome
proliferator-activated receptors (PPARs) consist of
three receptors α, β, and γ. PPAR-γ is expressed in
adipose tissue. It has recently been shown that two
polymorphisms in the PPAR-γ gene are associated
with severe overweight among obese women. 37 The
exact mechanisms by which the PPAR-γ variant
affects adipose tissue mass are not known. Changes
in the activity or structure of the PPAR gene in
vivo may result in changes in expression of target
genes in differentiating cells. Alterations in
adipocyte differentiation may then lead to obesity.
2.6 Lifestyle
A number of lifestyle factors (other than cigarette
smoking) have been implicated in CHD. These
146
include diet, physical activity, psychosocial factors,
and excessive alcohol intake. There appears
to be a synergistic effect of lifestyle readjustments,
such as the combination of diet, exercise and abstinence
from smoking, in the primary prevention of
CHD in women. 38
2.6.1 Diet
Diet is an important determinant
of CHD risk both in
women and in men.
Epidemiological studies show
that diets low in saturated fat
and high in fruits, vegetables,
whole grains, and fiber are
associated with a reduction in
the risk of CHD. Consistent with early metabolic
feeding studies, recent epidemiological studies
suggest that replacing saturated and trans-unsaturated
fats with unhydrogenated monounsaturated
and polyunsaturated fats may be more effective in
preventing CHD in women than in reducing total
fat intake. 39 Clinical trials have shown reductions
in CHD events or angiographic outcomes for a
variety of dietary interventions: very low fat
diets, 40 diets low in saturated fat and high in
polyunsaturated fat, 41–42 a Mediterranean diet high
in oleic acid and ω-3 fatty acids, 43 and diets rich in
antioxidant fruits, vegetables, and legumes. 44 The use of alcohol
has a U-shaped
relationship with
regard to the risk
of CHD.
The
effect of food supplements such as vitamins B6,
B12, and folate, as well as flavonoids and soy
isoflavones, require further investigation in clinical
trials before firm conclusions can be made about
their potential to favorably affect cardiovascular
outcomes in healthy women and those with established
CHD.
2.6.2 Physical Activity
Diet alone failed to lower LDL cholesterol levels
in women with high-risk lipoprotein levels who
did not engage in aerobic exercise. A combination
of the NHLBI’s National Cholesterol Education
Program (NCEP) Step II Diet plus exercise beneficially
reduced LDL cholesterol compared with the