(American Journal of Clinical Nutrition) -- The recent worldwide increase in obesity has been attributed to environmental factors such as more sedentary lifestyles and excessive food intake.

In an article in the American Journal of Clinical Nutrition, Lahti-Koski et al. conducted a series of cross-sectional surveys of Finnish men and women with the aim of assessing the relationship between lifestyle variables and increased obesity over a 15-year period. Food choices, physical activity levels, alcohol consumption, and smoking history were investigated for their associations with body mass index (BMI) and obesity in 24,604 subjects. The results underscore the importance of regular exercise to maximize the chances of maintaining a normal weight.

Between 1982 and 1997, the authors conducted surveys every 5 years of participants aged 25-64, for a total of 11,857 men and 12,747 women at the conclusion of the study. Subjects completed a self-administered questionnaire on socioeconomic factors, medical history, perceived health, and lifestyle. During the 15 years of the study, obesity incidence levels rose from 15.4% to 19.8% in the men and from 17.2% to 19.4% in the women. Overweight levels rose from 45.5% to 48% in the men, but remained stable at 33% in the women. Among features that had a strong association with obesity were increased consumption of sausage and milk with low vegetable intake, and low physical activity levels. Obesity was more prevalent among women ex-smokers who never drank alcohol and also in male smokers who consumed more than ten drinks per week; and in women who performed physical work, but in men who did not.

Changes in physical activity levels over time had the strongest relationship with increasing BMI in the cohort. An increasing intensity level of physical activity during work and leisure time was inversely associated with obesity. The authors conclude that a physically active lifestyle together with abstention from smoking, moderate alcohol consumption, and a variety of healthy foods provide the greatest likelihood of avoiding obesity.