Prevalence and association of physical activity with obesity: an urban, community-based, cross-sectional study.

AIM: To study levels of physical activity and various measures of obesity and their association in an urban population. STUDY
DESIGN: Cross sectional.
MATERIALS AND METHODS: One thousand and forty-seven individuals between the ages 25-64 years systematically sampled from a community-based population database were contacted through a house-to-house survey. We adopted the WHO STEPS guidelines for conducting this study. Anthropological measures collected were height, weight, and waist and hip circumference.
RESULTS: Physical Activity (PA) levels declined with age and the decline was greater among females. The Pearson's correlation coefficient for age against PA among males was found to be negative and weak (r = -0.104) and that among females was found to be similar (r = -0.206). The prevalence of obesity was higher among females (28.8 %) than among males (13.3 %) and the difference was statistically significant. There was a progressive increase in abdominal obesity with age in both genders. The prevalence of overweight and obesity was higher among individuals with low levels of PA as compared to those with high levels of PA.
CONCLUSION: Sedentary behavior is prevalent in more than half of the current study sample. This was more so with increasing age, female gender and increasing obesity. PA is an important component on long-term weight control, and therefore adequate levels of activity should be prescribed to combat the obesity epidemic. Habitual moderate physical activity may be beneficial in preventing excess accumulation of fat.

Introduction

Physical activity (PA) levels have declined globally in recent decades.(1) Regular PA decreases many of the health risks associated with obesity or being overweight.(2)

Leisure time PA has a major impact on the occurrence of coronary heart diseases and overall mortality.(3) There is also a graded inverse relationship between the total PA and mortality.(4) A review of epidemiological evidence regarding PA and cardiovascular diseases showed substantial evidence from many different populations that leisure time PA is associated with reduced risk of coronary heart disease (CHD) and cardiovascular mortality in middle-aged and older individuals.(5)

Obesity has doubled in every region of the world between 1980 and 2008. Recent data from WHO suggests an increasing prevalence of hypertension and diabetes as a result of increasing obesity.(6) Ecological analyses seem to imply that the increase in the prevalence of obesity is more strongly related to lower levels of PA than higher energy intakes.(7) In the current study, we focused on assessing levels of PA and various measures of obesity and their mutual association in an urban population in North India.

Materials and Methods

This was a cross sectional study conducted in Ludhiana, a major industrial town in Northern India.

Sample size calculation

Assuming a prevalence of high physical activity of 15% and an absolute precision of ±2%, a sample size of 1225 was calculated. Adjusting for a non-response rate of 10%, a total sample size of 1347 was calculated and rounded off to 1400.

Demographic data for the near 20,000 residents in our urban field practice area in Field Ganj, Ludhiana was regularly collected and entered into a computerized database, as part of our Family Folder System - a methodology for use in our area. A list of 8088 individuals between the ages of 25-64 years was abstracted from this database. Data from this population was used to sample every fifth individual from the area systematically. Sampled individuals were contacted by a house-to-house survey. We adopted the WHO STEPS guidelines for this study and used the recommended questionnaire.(8) Of a calculated sample size requirement of 1400 individuals, a sample of 1047 residents could be contacted. Respondents were interviewed at home using the STEP 1 questionnaire, after obtaining informed consent. Anthropological measures collected included height, weight, and waist and hip circumference of each participant. Weight was recorded using electronic weighing scales (Omron). Standing height was recorded up to the nearest centimeter.

Definition of risk factors

BMI is the simplest and most widely accepted measure of obesity.(9) WHO defines overweight as a BMI ≥25-29.99. Obesity is defined as BMI greater than or equal to 30. We also measured Waist Circumference (WC) and Waist-Hip Ratio (WHR) and categories were adopted from the WHO Expert committee recommendations.

Physical activity

Details of PA were calculated from the total time spent in such activity in a typical week as Metabolic Equivalents (METs). One MET is defined as the energy cost of sitting quietly, and is equivalent to a caloric consumption of 1 kcal/kg/hour. PA was categorized into “high” (moderate and vigorous intensity activities achieving a minimum of at least 3,000 MET minutes per week), “moderate” (moderate and vigorous intensity activities achieving a minimum of at least 600 MET minutes per week), and “low” none of the criteria mentioned above were fulfilled.(10)

Statistical methods

Data were entered using Epidata Entry software. Statistical analyses were performed using, Epidata Analysis (Epidata Association Denmark)(11) and Epi Info 3.5.4 (CDC, Atlanta, Georgia). Descriptive statistics and 95% confidence intervals were calculated and tabulated for relevant measures. Univariate analysis was done using the chi-square test and multivariate analysis was done using multiple logistic regression. Crude and adjusted odds ratios were calculated.

Results

In the current study, physical activity was low in more than half the sampled population and was related to increasing prevalence of obesity. The prevalence of obesity according to the various measures, showed an increasing prevalence with increasing age.

Age-sex distribution, educational, and main work statuses of the individuals are shown in Table 1. The prevalence of low levels of PA (sedentary lifestyle) was 56.7% in this sample with males (53.5%) having a lower prevalence than females (58.9%) [Table 2]. Prevalence of low PA levels among males increased from 54.3% in the age group 25-34 years, to 58.8% in the age group 55-64 years. The same increased among females from 50.7% to 72.9%. Overall, PA levels declined with age and decline was greater among females. This decrease was statistically significant among females (Pearson correlation co-efficient r = −0.21, P < 0.05).

Table 1

Demographic characteristics of the population

Table 2

Prevalence of physical activity according to age group and gender

Association of age and gender with various measures of obesity is shown in Table 3. In each age group, the prevalence of being overweight was higher among females than among males, and the differences were statistically significant. Prevalence of overweight among both genders increased with age till age group 45-54 years and then decreased. Prevalence of obesity increased with age among males all through and that among females increased till age group 45-54 years and then declined. Similarly, the prevalence of obesity was higher among females than males across all age groups, and the difference was statistically significant (P < 0.05).

Table 3

Distribution of overweight, obesity, WC and WHR according to age and gender

The prevalence of abdominal obesity (high WC) was three times higher among females as compared to males in all the age groups and the differences were statistically significant. In addition, a rising trend with age, of abdominal obesity was observed in both genders.

The prevalence of high WHR was significantly higher among males as compared to females, indicating more abdominal fat accumulation. The prevalence of high WHR increased with age in both genders.

Univariate and multivariate analysis was performed to observe the interrelationship of age, sex, and PA with overweight, obesity, high WC, and WHR [Table 4]. In this table, high and moderate PA was combined as “physically active”, and then compared with the sedentary group. There was a significant positive association between sedentary lifestyle and the various anthropological parameters (overweight, obesity, high WHR, and high WC) even after adjusting for age and gender. The adjusted odds ratios for exposure factors (age, gender, and PA) did not show any changes in their associations, in the direction of the risk, or significance, though there were differences in the strength of association.

Table 4

Univariate and multivariate analysis showing factors associated with overweight, obesity, high waist circumference and high waist hip ratio

Discussion

Prevalence of PA

Studies on physical activity in India have shown varied results and differences according to region, gender, urban versus rural areas and between socioeconomic classes. In the current study, sedentary behavior (Low PA level) was seen in 53.5% of males and 58.9% of females [Table 2]. A large, India-wide study by R.B. Singh et al. showed the overall prevalence of sedentary behavior was 59.3% among women and 58.5% among men.(12) Both sedentary behavior and mild activity showed a significant increasing trend in women after the age of 35-44 years. In men, such a trend was observed above the age of 45 years.

A recent study done using cluster sampling in 6198 subjects (3426 men and 2772 women) from eleven cities across India showed that 38.8% of men and 46.1% of women were physically inactive, and these figures are lower than those reported in the present study.(13)

Prevalence of obesity

In the current study, obesity was present in 22.5% of the sampled population (235/1046). Of these, women showed a significantly higher prevalence (28.8%) as compared to men (13.3%). Association of age with various measures of obesity between genders is shown in Table 3.

National Family Health Surveys 2 and 3 showed an increasing prevalence of obesity in Indian women from 10.6% in 1998-99 to 12.6% in 2005-2006.(14) This is less than that seen in the current study. The Jaipur Heart Watch (JHW) studies, in their four cross-sectional evaluations showed an increasing prevalence of obesity among both men and women (in men was 9.4, 21.1, 35.6, 54.0, and 50.9 [r2 = 0.92, P = 0.009] and in women 8.9, 15.7, 45.1, 61.5, and 57.7 [r2 = 0.88, P = 0.018] in JHW 1, JHW 2, JHW 3, and JHW 4, respectively).(15) These values in the last two surveys are higher than those found in the current study.

Physical activity and obesity

The five city study in India by Singh et al. has shown sedentary behavior to be significantly associated with obesity in both sexes, as seen in the current study.(12) A study from south India by Thankappan et al. also reported an increase in the prevalence of overweight and obesity with age and higher prevalence among women. With increase in PA, the prevalence of overweight and high WC decreased, which was statistically significant (P < 0.05).(16) This is demonstrated in the current study as well.

In a study by Mohan et al. (2005), multiple regression analysis (adjusted for age and sex) of WHR by socioeconomic and behavioral characters revealed that occupation, housing, marital status, smoking condition, physical exercise, drinking habits, and diet pattern cumulatively explains 75% (R2 = 0.75) of total variation of WHR in the study population.(17) This is partly demonstrated in the current study as well [Table 4] showing association of increasing obesity with increasing age, female gender, and low physical activity.

Conclusions

Sedentary behavior is prevalent in more than half of the current study population. This was more so with increasing age, female gender, and increasing obesity. PA is an important component on long-term weight control, and therefore, adequate levels of activity should be prescribed to combat the obesity epidemic. Habitual moderate physical activity may be beneficial to prevent excess accumulation of fat.