Physical activity, cardiorespiratory fitness and body mass index as predictors of substantial weight gain and obesity: the Canadian physical activity longitudinal study.

BACKGROUND Obesity is a growing health issue in Canada and the identification of the determinants of obesity is important for the development of prevention strategies. The purpose of this investigation was to determine the relationships between physical activity, cardiorespiratory fitness, body mass index (BMI), and the development of future obesity. METHODS The sample included 459 adults (18+ y; 223 men, 236 women) from the Canadian Physical Activity Longitudinal Study (PALS; 2002-04). Data on physical activity, smoking, alcohol consumption, BMI, and cardiorespiratory fitness (VO2max) were collected in 1981 and 1988. The mean BMI, physical activity, and VO2max were calculated across the 1981 and 1988 measures. Self-reported height and weight were collected in the 2002-04 survey, and participants were classified as overweight (BMI 25 to 29.9 kg/m2) or obese (BMI 230 kg/m2). Logistic regression was used to predict overweight, obesity or substantial weight gain (10 kg or more) in 2002-04, controlling for age, sex, smoking and alcohol use. RESULTS Higher VO2max in 1981-88 was associated with lower odds of obesity in 2002-04 (OR = 0.87; 95% Cl: 0.76-0.99, p < 0.05), and higher BMI in 1981-88 was associated with higher odds of obesity in 2002-04 (1.84; 1.52-2.20, p < 0.0001). In women, higher VO2max (0.82; 0.72-0.93) resulted in lower odds of a 10 kg weight gain. CONCLUSIONS The results indicate that cardiorespiratory fitness and previous BMI are important predictors of future weight gain and obesity, and should be incorporated in strategies to identify individuals at increased risk of obesity.