The increasing prevalence of obesity in New Zealand: is it related to recent trends in smoking and physical activity?
Simmons, G.; Jackson, R.; Swinburn, B.; Yee, R.L.
New Zealand Medical Journal 109(1018): 90-92
1996
ISSN/ISBN: 0028-8446 PMID: 8606842 Document Number: 463815
Aims. To describe recent trends in body mass in Auckland, and to determine whether associated changes in cigarette smoking and physical activity could explain these trends. Methods. Risk factors for coronary heart disease were measured in three age-stratified random samples of Europeans aged 35-64 years using a standard protocol in 1982, 1986-8 and 1993-4. Body mass index (BMI) was calculated as weight in kg/(height in m-2), with overweight or obese being defined as BMI gt 25. Results. The age-standardised mean BMT increased from 25.6 (25.4-25.8) to 26.4 (26.2-26.7) in men and from 24.6 (24.2-24.9) to 25.1 (24.8-25.5) in women between 1982 and 1993-4. The prevalence of overweight and obese people increased from 52.8% (48.1-57.7) to 64.2% (58.1-70.3) in men and from 36.5% (31.5-41.5) to 44.9% (39.7-50.1) in women. Self reported cigarette smoking declined between 1982 and 1993-4 with an associated increase in the prevalence of ex-smokers. The change in smoking status accounted for only 7% and 10% of the observed increase in BMI in men and women respectively. Most of the observed change in BMI was due to a general increase in BMI in all smoking categories in both sexes. The prevalence of leisure time physical activity increased in both sexes between 1986-88 and 1993-4 while work physical activity decreased. The change in physical activity should have decreased mean BMI by approximately 4% in men and 14% in women. As with smoking there was a trend towards increasing mean BMI irrespective of the activity undertaken. Conclusion. Recent trends in smoking cessation explain only a small percentage of the increase in body mass while the trends in physical activity would have predicted a small decrease in the prevalence of obesity, contrary to the observed trends. By exclusion, an increase in total energy intake, is the most likely explanation for the observed trends.