Can Physical Activity Attenuate Aging-related Weight Loss in Older People? The Yale Health and Aging Study, 1982-1994

James Dziura, Carlos Mendes de Leon, Stanislav Kasl, and Loretta DiPietro

Background

• Body weight increases through middle-age, but starts to decline during older age;

• This decline occurs primarily as a result of loss in lean tissue (sarcopenea);

• Sarcopenea is a primary condition for loss of physical and metabolic reserve in aging;

• Disuse has been identified as a significant factor in lean tissue loss, since changes in body composition are mirrored by a gradual decline in physical activity in older age.

Problem

• Longitudinal studies of physical activity and weight change have not been performed in older populations, among whom weight loss is a more important problem than weight gain and among whom the relation between physical activity and weight loss is influenced heavily by chronic disease and loss of mobility.

Purpose

The purpose of this analysis was to determine, longitudinally, the trajectory of weight loss with age and the relation between physical activity and body weight change in a cohort of people aged 65 years and older.

Hypotheses

We hypothesized that: 1) body weight would decline over the follow-up; and 2) physical activity would play an important role in minimizing weight loss over time.

Methods

Subjects

Older residents (≥65 y) of New Haven, CT enrolled in the Yale Health and Aging Project – one of the funded sites of the Established Populations for the Epidemiologic Study of the Elderly (EPESE).

Methods

Subjects

The New Haven EPESE cohort was a cluster sample stratified by three different housing types for older people: 1) public housing; 2) private housing; and 3) housing in the general community.

•Of the 3,337 eligible residents contacted, 2,812 (82%) enrolled in the study at baseline in 1982.

Exclusion Hierarchy

Interested subjects (N=2,812)

Methods

Body weight

•Current body weight was self-reported at each yearly interview from 1982 to 1990 and then again in 1994.

•Each subject could have as many as 10 weight assessments over the 12-year follow-up.

Methods

Physical Activity

•Respondents were asked to report the frequency of participation within the past month for four general types of activities: 1) walking; 2) gardening/housework; 3) physical exercise; and 4) active sports or swimming.

•Responses of never (coded as 0), sometimes (coded as 1) or often (coded as 2) were summed over the four activities for each respondent to create a total activity score (TAS) that ranged from 0 to 8, with higher scores indicating higher levels of baseline activity.

Covariables at Baseline

• Age (date of initial interview - reported birth date);

• Height (inches);

• Race (white/non-white);

• Education (number of years);

• Chronic conditions (reported number of physician-diagnoses of heart disease, cancer, stroke, diabetes, liver disease, or hypertension);

• Smoking (smoker/non-smoker);

• Functional Ability Score (ADLs, IADLs);

• Mobility Score (reported ability (yes/no) to climb stairs, do house work, and walk ½ mile)

Statistical Analysis

• Univariate statistics (Χ±SD; %);

• Multivariable random effects modeling (repeated body weight assessments over a maximum of 10 times (1982-1994) regressed on physical activity, while adjusting for covariables). This modeling accounts for between-subject variation in baseline body weight (intercept) and change in body weight with aging (slope; as indicated by follow-up time variable).

Table 1. Cross-sectional distribution of mean (±sd) body weight at each year of follow-up among those who survived and those who did not

survive to the next interview year.

YEAR N

Body weight

(lbs) N

Body weight

(lbs)

1982 2199 154±31 60 153±28

1983 2142 152±30 36 151±26

1984 1965 151±31 79 148±29

1985 1832 152±32 14 160±21

1986 1749 150±31 30 152±27

1987 1572 149±31 82 144±26

1988 1397 149±31 18 154±24

1989 1326 146±31 64 151±31

1990 1093 145±31 40 153±24

Survived to next interview year Did not survive to next interview year

Table 2. – Baseline characteristics of the study sample by survival status over the follow-up, 1982-1994.Variable Survivors

(N=905)

Non-survivors

(N=1395)

Age (yrs) 71±5 76±7 *

Sex (% Female) 69% 51% #

Race (% White) 78% 81%

Education (yrs) 10±4 9±4 *

Disability score 0.13±0.60 0.43±1.30 *

Mobility score 0.39± 0.76 0.87±1.06 *

Chronic conditions 1±0.77 1±0.92

Smokers (%) 18% 23%

Height (in) 64.3±3.58 64.9±3.71

Weight (lbs) 155±30 153±32

Total Physical Activity Score

2.62±1.78 2.11±2.19 *

* p<0.001 based on t-test for independent samples; # p<0.01 based on chi-square test.

Figure 2. - Predicted weight loss (95% confidence bands) over the first 8 years based on random effects modeling*: 1982-1990.

110

120

130

140

150

160

1982 1983 1984 1985 1986 1987 1988 1989 1990

Survivors

Non-survivors

YEAR

Body weight (lbs)

* Model adjusted for age, sex, housing strata, and interaction of each with time.

Table 3. - Simple effects of physical activity on weight loss: 1982-1994.

Variable Estimate 95% CI Estimate 95% CI Estimate 95% CI

Total Activity Score

Total Activity Score * Time

1.29

0.16

0.57, 2.00

0.10, 0.22

1.19

0.05

0.13, 2.25

-0.01, 0.11

1.19

0.20

0.21, 2.17

0.09, 0.31

Based on random effects modeling adjusted for time and time2. Regression estimates for TAS*Time interaction represent the change in the rate (per year) of weight loss per unit change in the study variable.

Non-survivors (n=1,395)Combined (N=2,300) Survivors (n=905)

Table 4. Parameter Estimates* from the Random Effects Model Determining the Effects of Physical Activity on Aging-Related Weight Change.

Variable Parameter estimate

95% CI Parameter estimate

95% CI Parameter estimate

95% CI

Baseline Age -1.04 -1.21, -0.87 -0.78 -1.12, -0.45 -1.12 -1.34, -0.91

Time -1.77 -2.19, -1.35 -0.25 -0.73, 0.24 -2.31 -3.14, -1.47

Time2 -0.04 -0.05, -0.02 -0.04 -0.06, -0.03 -0.13 -0.16, -0.09

Age * Time -0.07 -0.08, -0.05 -0.04 -0.06, -0.02 -0.03 -0.06, -0.01

Chronic condition

3.94 1.73, 6.16 9.97 3.97,16.0 2.38 -2.63, 7.38

Chronic condition * Time

-0.15 -0.36, 0.06 -0.34 -0.75, -0.01 0.08 -0.56, 0.72

TAS -0.83 -1.76, 0.10 0.25 -1.43, 1.92 -1.03 -2.93, 0.87

TAS * Time 0.09 0.02, 0.15 -0.03 -0.12, 0.06 0.18 0.00, 0.37

TAS*Chronic condition

----- ----------- -0.91 -2.76,0.95 -0.37 -2.18, 1.43

TAS*Chronic condition*Time

----- ---------- 0.12 0.01,0.24 -0.10 -0.32, 0.12

Mobility -3.41 -6.08, -0.74 -6.12 -11.2, -1.08 -3.12 -6.38, 0.14

Mobility*Time 0.36 0.09, 0.63 -0.22 -0.53, 0.08 0.41 -0.02, 0.84

Smoking

Smoke * Time

-10.30

0.24

-12.9, -7.70

-0.02, 0.50

-10.20

0.23

-14.5, -5.98

-0.04, 0.49

-10.05

0.52

-13.4, -6.70

0.07, 0.97

Combined (N=2,300) Survivors (n=905) Non-survivors (n=1,395)

*also adjusted for sex, race, education, height, functional disability score, and housing.

Fig. 3 - Parameter Estimates (95% CI)* from the Fully-Adjusted Random Effects Model Determining the Effects of Physical Activity Score on Attenuation of

Weight Loss by Survival and Chronic Disease Status.

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Combined (N=2300)

Survivors with no chronic disease (n=350)

Survivors with chronic disease (n=555)

Non-survivors with no chronic disease (n=422)

Non-survivors with chronic disease (n=973)

Attenuation of weight loss (lbs/year)

0.09 (0.02, 0.15)

-0.02 (-0.11, 0.07)

0.09 (0.00, 0.17)

0.06 (-0.12, 0.25)

0.15 (0.00, 0.30)

Summary

• The oldest people started off the follow-up period weighing less than their younger counterparts;

• The magnitude of the inverse relation between age and body weight was greater among nonsurvivors compared with survivors;

Summary

• We observed a curvilinear rate of weight loss with aging that varied by survival status and by chronic disease.

• The ability of physical activity to attenuate aging-related weight loss was observed only among those with chronic disease, and was most pronounced among those with chronic disease who did not survive the follow-up period.

Conclusion

If we were to consider weight loss a somatic indicator of frailty in older people, it appears as though even among older people afflicted with chronic conditions that contribute to frailty, an active lifestyle can attenuate the rate of failure, thereby maintaining some quality of health and function in older age.