|Abstract or Summary
- The US population over the age of 65 years is growing rapidly, with elderly
women outnumbering men by 50 percent. Studies show that aging is often
accompanied by reduced energy intake, inadequate nutrition, and the loss of lean
body mass with a subsequent increase in body fat, as well as the tendency towards
inactivity. An increased level of physical activity elevates energy needs, which can
lead to increased energy and nutrient intake, and has been shown to aid in the
maintenance of lean body mass and the reduction of body fat. Positive health
outcomes for seniors depends partly on a clearer understanding of the
interrelationships between physical activity, diet, and body composition.
The purpose of this study was to determine whether higher overall levels of
physical activity among elderly women, were related to higher energy intake, nutrient adequacy, and less body fat, and to what extent age affected these
associations. Sixty-three elderly women (aged 65-98 years) volunteers completed a
three part study spanning 14 weeks. Mean level of physical activity (MLPA) and
mean nutrient intakes were estimated using nine self-reported days of records, three
predetermined days from each of three recording periods. MLPA was determined
from self-reported hours spent in five physical activity categories (resting, very
light, light, moderate, and heavy), multiplied by corresponding weighted factors of
intensity (1.0, 1.5, 2.5, 5.0, 7.0, respectively). Nutrient analyses for seven
vitamins (vitamin A, vitamin C, thiamin, riboflavin, niacin, vitamin B6, vitamin
B12) and three minerals (calcium, iron, and zinc) were done using the Food
Processor II computer software. A mean adequacy ratio (MAR) was calculated for
each subject as the average percent of the RDA for intakes of all 10 nutrients.
Body composition assessment included triplicate measures of: height and weight
from which body mass index (BMI) was determined; waist-to-hip ratio (WHR); and
an estimation of percent body fat (PBF) from the sum of four skinfolds (triceps,
biceps, subscapular, suprailiac).
It was determined that MLPA was not directly related to energy intake,
nutrient adequacy, or the three body composition parameters. However, the
correlation coefficients between MLPA and energy intake, mean adequacy ratio, and
percent RDA for 8 of the 10 nutrients were positive, and the correlation coefficients
between MLPA and all three body fatness measures were negative, as was expected. The small coefficient of variability of MLPA limited its discriminating power in
determining associations with energy intake, nutrient adequacy, and body
Backward stepwise regression models were conducted to distinguish potential
confounding effects of age, education, and MLPA on the variables kcal/day,
kcal/kg/day, MAR, BMI, WHR, and PBF. Age was found to account for the
largest portion of the variations, and was greater than the contribution of MLPA for
all of these variables, except in the case of kcal/kg/day.
When the subjects were divided into young-old (65-74 yr) and old-old (75-98
yr) subgroups, the younger compared to the older women were found to be more
active as measured by MLPA (p=.02), explained by their engaging in more light
activities of daily living (p=.04). The young-old compared to the old-old women
consumed more kcalories/day (p=.01), and had a higher MAR score (p=.00). The
nutrient densities of the two groups' diets were not significantly different. The
younger women had slightly lower BMI, WHR, and PBF values.
This study revealed age, rather than MLPA, was a better predictor of some
parameters of diet adequacy and body fatness among this sample of elderly women.
In addition, consistently higher levels of physical activity and greater dietary
adequacy and was found among the younger compared to the older portions of this
sample of senior women, suggesting that nutrition intervention programs for the
elderly should encourage daily activeness as a strategy to maintain or improve
dietary adequacy with advancing age.