OBJECTIVE: We examined whether associations between dietary components and, in particular, energy density (ED) predicted subsequent 5-year weight changes. RESEARCH METHODS AND PROCEDURES: The present longitudinal population study was part of the Danish World Health Organization Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) and the 1936 cohort dietary studies. Effects of components were studied in relation to subsequent 5-year weight changes in 862 men and 900 women, 30 to 60 years old. Linear multiple regression analyses were conducted. RESULTS: Mean 5-year changes in body weight (BW) were 1.2 +/- 3.9 and 1.3 +/- 4.6 kg for men and women, respectively. In general, neither ED nor any of the dietary components was associated with subsequent change in BW. In women, ED was positively associated with weight gain among the obese (BMI > 30 kg/m2) and inversely associated with weight gain in normal-weight women (BMI < 25 kg/m2) (p = 0.01). However, in men there was a non-significant inverse trend between ED and weight gain in the obese and no significant interaction. DISCUSSION: To our knowledge, this is the first prospective study to examine the associations between ED and subsequent changes in BW, and despite a general belief that ED is a major determinant of obesity, the present study did not generally lend support for an association. However, among certain subgroups, an energy-dense diet may be a risk factor for weight development.