WEIGHT ISSUES
DIETARY FIBRE, WEIGHT GAIN, AND CARDIOVASCULAR DISEASE
RISK FACTORS IN YOUNG ADULTS
The prevalence of cardiovascular disease (CVD), after declining
steadily since mid-century, has been stable or increasing
over the past decade. Factors known to increase the risk
of CVD include age, obesity, central distribution of body
fat, smoking, physical inactivity, hypertension, dyslipidemias,
and abnormalities in blood clotting factors. Insulin resistance
associated with hyperinsulinemia is common to many of these
risk factors. Therefore, a study was carried out to examine
the role of fibre consumption and its association with insulin
levels, weight gain, and other CVD risk factors compared
with other major dietary components. The study group comprised
2,909 healthy adults aged 18 to 30 years at enrolment. It
was found that after adjustment for potential confounding
factors, dietary fibre showed linear associations from lowest
to highest quintiles of intake with the following: body
weight, waist-to-hip ratio, fasting insulin adjusted for
body mass index, and 2-hour postglucose insulin adjusted
for body mass index. Fibre was also associated with blood
pressure and levels of triglyceride, high-density lipoprotein
cholesterol, low-density lipoprotein cholesterol, and fibrinogen.
In comparison with fibre, intake of fat, carbohydrate, and
protein had inconsistent or weak associations with all CVD
risk factors.
Thus, fibre consumption predicted insulin levels, weight
gain, and other CVD risk factors more strongly than did
total or saturated fat consumption. High fibre diets may
protect against obesity and CVD by lowering insulin levels.
Ludwig, D.S. et al
J.A.M.A. 1999, 282 (16) 1539-46
DIETARY SODIUM INTAKE AND SUBSEQUENT RISK OF CARDIOVASCULAR
DISEASE IN OVERWEIGHT ADULTS
Observational epidemiologic studies have identified an
independent, positive relationship between dietary intake
of sodium and blood pressure. Trials have also demonstrated
that reduced sodium intake leads to a reduction in blood
pressure in both hypertensive and normotensive subjects.
Therefore, a study was carried out to examine the risk of
cardiovascular disease associated with dietary sodium intake
in overweight and non-overweight persons. The study group
consisted of 2,688 overweight and 6,797 non-overweight subjects
aged 25 to 74 years when the survey was conducted in 1971-1975.
Dietary sodium and energy intakes were estimated at baseline
using a single 24-hour dietary recall method.
It was found that for overweight and non-overweight persons,
over an average of 19 years of follow-up, the total number
of documented cases were as follows: 680 stroke events (210
fatal), 1,727 coronary heart disease events (614 fatal),
895 cardiovascular disease deaths, and 2486 deaths from
all causes. Among overweight persons with an average energy
intake of 7,452 kJ, a 100 mmol higher sodium intake was
associated with a 32% increase (relative risk [RR], 1.32)
in stroke incidence, 89% increase (RR, 1.89) in stroke mortality,
44% increase (RR, 1.44) in coronary heart disease mortality,
61% increase (RR, 1.61) in cardiovascular disease mortality,
and 39% increase (RR, 1.39) in mortality from all causes.
Dietary sodium intake was not significantly associated with
cardiovascular disease risk in non-overweight persons. Thus,
high sodium intake is strongly and independently associated
with an increased risk of cardiovascular disease and all-cause
mortality in overweight persons.
He, J. et al
J.A.M.A. 199, 282 (21) 2027-34
EFFECTS OF LIFESTYLE ACTIVITY VS STRUCTURED AEROBIC EXERCISE
IN OBESE WOMEN
Obesity is a serious and common health problem. Physical
inactivity contributes to weight gain, but only 22% of Americans
are regularly active. Therefore, a study was carried out
to examine the short- and long-term changes in weight, body
composition, and cardiovascular risk profiles produced by
diet combined with either structured aerobic or moderate-intensity
lifestyle activity. Such activity would include increasing
the amount of walking in the daily routine, performing more
yard work, and using the stairs when possible. Participants
in the study were given a program of either structured aerobic
exercise or moderate lifestyle activity and a low-fat diet
of about 1200 kcal/d. Changes in body weight, body composition,
cardiovascular risk profiles, and physical fitness were
assessed at 16 weeks and at 1 year. Mean weight losses during
the aerobic group and 7.9 kg for the lifestyle group. The
aerobic group lost significantly less fat-free mass (0.5
kg) than the lifestyle group (1.4-kg).
During the 1-year follow-up, the aerobic group regained
1.6 kg, while the lifestyle group regained 0.08 kg. At week
16, serum triglyceride levels and total cholesterol levels
were reduced significantly from baseline but did not differ
significantly between groups. Thus a program of diet plus
lifestyle activity may offer similar health benefits and
be a suitable alternative to diet plus structured aerobic
activity for obese women.
Anderson, R.E. et al,
J.A.M.A. 1999, 281 (4) 335-40
ABDOMINAL ADIPOSITY AND CORONARY HEART DISEASE IN WOMEN
Obesity is well recognised as a major risk factor for coronary
heart disease (CHD) in men and women, but whether regional
fat distribution contributes independently to risk factor
remains unclear. Therefore, a study was carried out to compare
waist-hip ratio (WHR) and waist circumference in determining
the risk of CHD in women. The study group consisted of 44,702
women participating in the Nurses’ Health Study (1986-1994)
who were free of prior CHD, stroke, or cancer in 1986. During
8 years of follow-up there were 320 CHD events (251 myocardial
infarctions and 69 CHD deaths). Higher WHR and greater waist
circumference were independently associated with a significantly
increased age-adjusted risk of CHD. After adjusting for
body mass index (BMI) and other cardiac risk factors, women
with a WHR of 0.88 or higher had a relative risk (RR) of
3.25 for CHD compared with women with a WHR of less than
0.72. A waist circumference of 96.5 cm (38 in) or more was
associated with a RR of 3.06. Additionally, the WHR and
waist circumference were independently strongly associated
with increased risk of CHD also among women with a BMI of
25kg/m2 or less. After adjusting for reported hypertension,
diabetes, and high cholesterol level, a WHR of 0.76 or higher
or waist circumference of 76.2 cm (30 in) or more was associated
with a more than 2-fold higher risk of CHD.
Rexrode, K.M. et al
J.A.M.A. 1998, 280 (21) 1843-48
CHANGE IN BODY FAT, BUT NOT BODY WEIGHT OR METABOLIC CORRELATES
OF OBESITY, IS RELATED TO RELIEF OF OBESE PATIENTS WITH
OSTEOARTHRITIS
Osteoarthritis (OA) of the knee is the most common joint
disorder, accounting for a large proportion of disability
in adults. One factor often cited as a possible cause of
OA in general and in knee OA in particular is obesity. A
study was therefore carried out to determine the variable
most closely related to symptomatic relief of OA of the
knee in response to a weight control program. The study
group consisted of 22 patients diagnosed with knee OA whose
body mass index (BMI) was more than 26.4. The patients were
treated with a low calorie diet, an appetite suppressant,
and nonsteroidal anti-inflammatory drugs for 6 weeks and
were instructed to follow a walking program. BMI, percent
body fat, the average number of steps per day by pedometer,
and the metabolic correlates of obesity (blood pressure,
fasting blood serum glucose, total cholesterol, triglycerides,
and serum insulin) were measured at the beginning and end
of therapy.
It was found that the remission score of knee OA (using
the Severity Index of Lequesne) was more strongly associated
with reduction in percent body fat than other variables.
A significant correlation was also observed between the
number of steps per day and remission score. Thus, in a
weight control program, decreasing body fat and increasing
physical activity are more important than body weight loss
or decreasing other indices of obesity in producing symptomatic
relief of knee OA.
Toda, Y. et al
J. RHEUMATOL. 1998, 25 (11) 2181-6
IMPAIRMENT OF HEALTH AND QUALITY OF LIFE IN PEOPLE WITH
LARGE WAIST CIRCUMFERENCE
A study was carried out to define the symptoms associated
with excess central fat distribution and to assess the risks
of chronic disorders. A cross-sectional study of 5,887 men
and 7,018 women aged 20-59 years assessed respiratory insufficiency,
low back pain, degree of physical function, presence of
non-insulin-dependent diabetes, and cardiovascular risk
factors. Bodyweight, body-mass index, and waist circumference
were measured by action levels (men; less than action level
1 <94.0 cm, action levels 1-2 94.0-101.9 cm, more than
action level 2 >102.0 cm; women: less than action level
1 <80.0 cm, action levels 1-2 80.0-87.9 cm, more than
action level 2 >88.0 cm). The reference group were people
with waist circumferences lower than action level 1. It
was found that all symptoms and risks increased among participants
higher than action level 2, after adjustment for age and
lifestyle, by 3.1 in men and 2.7 in women for shortness
of breath when walking upstairs; 4.5 and 3.8 for non-insulin
dependent diabetes; and 4.2 and 2.8 for at least one major
cardiovascular risk factor. Above action level 2, compared
with the reference group, men and women were at twice the
risk of difficulties in everyday life, and women were 1.5
times more likely to have low back pain or symptoms of intervertebral
disc herniation. The researchers conclude that waist action
levels could be useful for health promotion to raise awareness
of the need for weight management.
Lean,M.E. et al
LANCET 1998, 351 (9106) 853-56
THE EFFECT OF AGE ON THE ASSOCIATION BETWEEN BODY-MASS
INDEX AND MORTALITY
Mortality was studied over 12 years in 62,116 men and 62,019
women who participated in the American Cancer Society's
Cancer prevention Study and who had no history of heart
disease, stroke or cancer (other than skin cancer) at base
line in 1959. Greater body-mass index was associated with
higher mortality from all causes and from cardiovascular
disease in men and women up to 75 years of age. For mortality
from cardiovascular disease, the relative risk associated
with an increment of 1 in the body mass index was 1.10 for
30-44 year old men and 1.03 for 65-74 year old men. The
corresponding relative risks for women were 1.08 and 1.02.
The researchers conclude that excess body weight increases
the risk of death from any cause and from cardiovascular
disease in adults between 30 and 74 years of age, and that
this relative risk is higher among younger subjects.
Stevens,J. et al
NEW ENG. J. MED. 1998, 338 (1) 1-7
