Prospective study of self-reported usual snacking and weight gain in a Mediterranean cohort: The SUN project

Background & aims: It has been hypothesized that snacking could be a major factor in the development of obesity. However, the relationship between snacking and the increment in body weight remains controversial. Moreover, longitudinal studies about this issue are scarce. Thus, our objective was to prospectively assess the relationship between snacking and weight gain and obesity in a middle-aged free-living population. Methods: Longitudinal prospective Spanish dynamic cohort (10,162 university graduates; mean age: 39 years) followed-up for an average of 4.6 years. Dietary habits were ascertained through a validated 136-item food-frequency questionnaire. Usual snackers were defined as those participants who answered affirmatively when asked in the baseline assessment if they usually eat between meals. Validated self-reported weight and body mass index were collected at baseline and during follow-up. Results: After adjusting for potential confounders, self-reported between-meal snacking was significantly associated with a higher risk of substantial weight gain (>= 3 kg/year; p < 0.001; >= 5 kg/year, p < 0.001; >= 10% baseline weight, p < 0.001). Among participants with a baseline body mass index lower than 30 kg/m(2) (n: 9709) we observed 258 new cases of obesity. Usual snackers presented an adjusted 69% higher risk of becoming obese during follow-up (Hazard Ratio: 1.69; 95% confidence interval: 1.30-2.20). Conclusion: Our results support the hypothesis that self-reported between-meal snacking can be a potential risk factor for obesity. (c) 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.