The inverse relationship between steps/day and obesity
Despite common knowledge that both obesity and type 2 diabetes are increasing on a global scale, mainly due to drops in physical activity (PA), studies based on the direct association between PA and obesity are scant and usually incomplete. The major flaw of most of these studies is the failure to include walking around the house and workplace or any other form of incidental daily activity as forms of PA. As pedometers are now readily accessible, gauging the exact number of daily steps and their relationship to obesity is now a feasible possibility. Based on that knowledge, a study was conducted by an Australian research team. The study was designed to: 1) describe the association between recent PA (measured by both a pedometer and a questionnaire) and waist circumference and body mass index (BMI), and 2) compare the two associations; that is: steps/day as measured by a pedometer and weekly PA by the questionnaire with the aforementioned measures of obesity.
All adults aged 25 and over on the island of Tasmania, Australia, were contacted and asked to participate in the study. 40% of those invited responded and chose to partake. A total of 1,126 subjects agreed to fill out a questionnaire and wear a pedometer for two weekdays. The two pedometers used were the Omron HJ-003 and HJ-102, which both rate fairly well according pedometer tests. They were both reportedly checked regularly to ensure accuracy. Each subject was given a pedometer with instructions and a diary, and was told to record steps for two average days. As for the questionnaire, participants were first asked to provide a personal rating of their PA level, which was estimated by the time spent walking for recreation or transport, moderate intensity non-work, non-domestic activity and vigorous activity (which counted double) during the past week. The next parts of the survey included a report of the time spent watching TV over the past week and a set of dietary questions that assessed alcohol and tobacco intake. Finally, waist circumference, height, weight and BMI were each measured using a precise system.
Results showed differentiations between genders in every category except average daily steps, current smoking status and weekly hours of TV watching. Though men showed higher rates of overall weekly PA (6.4 hours/week compared to 4.5), their daily walking amounts were extremely close in range to that of women (both around 11,000). This may suggest that women walk just as much as men, but don't consider it to be a form of physical activity that they would fill out on the questionnaire.
Since the majority of associations were different for men and women, gender-specific models were subsequently built that focused on the direct relationship of the same variables to waist circumference and BMI individually. Results for waist circumference showed that the association of daily step count was the most highly significant of the PA measures for both men and women. The association between daily step count and BMI was significant for men and somewhat significant for women, while on the contrary, PA time measured by the questionnaire was not significantly associated with BMI. These findings show a strong correlation between walking and both waist circumference and BMI, though it goes undetected by the questionnaire.
Additional results analyzed the impact of increasing daily steps by 2,000 on waist circumference and BMI. The decline in those obesity measures varied according to baseline activity, but was much greater for those who spent much large amounts of time sedentary or with low daily step counts. This exemplifies the importance of taking baseline activity and health into consideration when studying the effects of daily step increase. It also provides a theoretical model that displays how a decrease in obesity would come about at an easier rate for those walking less than 10,000 steps daily. Factors such as diet and other daily patterns need to also be taken into consideration when interpreting overall causes for PA habits. Using the daily step tally provided by the usage of pedometers added a more precise tool in assessing daily PA compared to the less substantial questionnaire, and should be relied upon more often in the future as an accurate measuring stick. The study as a whole should serve as further evidence for physicians and health professionals for recommending increases in daily activities--especially walking--to obese and overweight patients. One interpretation that could be passed on is the more severe a case of obesity happens to be, the more rapid positive changes in waist circumference and BMI will come about. In effect, although walking might be more difficult for the extremely obese, it will turn around quicker and more substantive results than it will for those in better shape.
-As reported in The National Journal of Obesity
-By Greg Gargiulo
