Marques-Vidal et al. BMC Public Health 2011, 11:772 http://www.biomedcentral.com/1471-2458/11/772 Table 2 Prevalence of overweight and obesity, by survey year, sex and age group Gender/age group Men Overweight (%) 18-24 25-34 35-44 45-54 55-64 65-74 75+ Obesity (%) 18-24 25-34 35-44 45-54 55-64 65-74 75+ Women Overweight (%) 18-24 25-34 35-44 45-54 55-64 65-74 75+ Obesity (%) 18-24 25-34 35-44 45-54 55-64 65-74 75+ 1995-6 20.9 (19.4 - 22.5) 36.1 (34.3 - 37.9) 44.4 (42.6 - 46.1) 49.9 (48.1 - 51.7) 46.9 (45.0 - 48.7) 43.6 (41.7 - 45.5) 37.8 (35.3 - 40.4) 2.1 (1.5 - 2.6) 6.6 (5.6 - 7.5) 11.1 (10.0 - 12.3) 13.4 (12.2 - 14.6) 15.7 (14.4 - 17.0) 13.0 (11.7 - 14.3) 7.8 (6.4 - 9.2) 10.7 (9.4 - 11.9) 23.1 (21.5 - 24.7) 34.1 (32.4 - 35.7) 39.0 (37.4 - 40.7) 41.1 (39.4 - 42.7) 39.9 (38.1 - 41.6) 29.3 (27.4 - 31.2) 2.0 (1.4 - 2.5) 5.6 (4.7 - 6.4) 11.4 (10.3 - 12.4) 17.8 (16.5 - 19.1) 19.0 (17.7 - 20.3) 16.1 (14.8 - 17.4) 11.7 (10.3 - 13.0) 1998-9 20.5 (18.9 - 22.1) 36.6 (34.8 - 38.4) 46.9 (45.1 - 48.7) 49.7 (47.9 - 51.4) 49.9 (48.0 - 51.7) 47.9 (46.0 - 49.8) 42.7 (40.2 - 45.2) 3.2 (2.5 - 3.9) 7.1 (6.1 - 8.0) 11.8 (10.7 - 13.0) 15.0 (13.7 - 16.3) 16.2 (14.8 - 17.6) 14.9 (13.5 - 16.3) 10.1 (8.6 - 11.7) 10.4 (9.1 - 11.7) 21.9 (20.4 - 23.4) 32.1 (30.5 - 33.7) 38.9 (37.2 - 40.5) 41.1 (39.4 - 42.7) 39.7 (38.0 - 41.4) 33.5 (31.6 - 35.5) 2.3 (1.6 - 2.9) 6.4 (5.5 - 7.3) 11.9 (10.8 - 13.0) 19.4 (18.1 - 20.7) 20.3 (18.9 - 21.7) 19.3 (17.9 - 20.7) 14.2 (12.7 - 15.6) Page 5 of 8 2005-6 16.8 (15.0 - 18.6) 39.7 (37.4 - 42.1) 46.0 (43.7 - 48.2) 47.4 (45.2 - 49.6) 48.3 (46.0 - 50.6) 47.2 (44.9 - 49.6) 43.8 (41.0 - 46.6) 3.7 (2.8 - 4.6) 8.3 (7.0 - 9.6) 13.9 (12.3 - 15.4) 19.5 (17.7 - 21.2) 20.1 (18.3 - 22.0) 17.7 (15.9 - 19.5) 12.9 (11.0 - 14.7) 10.2 (8.6 - 11.7) 21.5 (19.5 - 23.4) 28.5 (26.6 - 30.5) 37.0 (35.0 - 39.0) 42.4 (40.3 - 44.6) 41.8 (39.7 - 43.8) 32.8 (30.4 - 35.1) 2.7 (1.9 - 3.5) 8.0 (6.6 - 9.3) 13.5 (12.0 - 14.9) 20.5 (18.8 - 22.1) 22.8 (21.0 - 24.6) 22.6 (20.8 - 24.4) 16.6 (14.8 - 18.4) Overweight was defined as a body mass index (BMI) ≥25 and <30 kg/m2; obesity was defined as a BMI ≥30 kg/m2. Results are expressed as percentage and (95% confidence interval). levels, and it is thus likely that these increases, if objec- Our findings are partly in agreement with a prospective tively measured, could have been even greater. Interest- study conducted in Northern Portugal [11] which ingly, mean and median BMI increased similarly during showed a similar incidence of obesity irrespective of the study period, suggesting an overall shift of the BMI educational level in men, while a lower incidence was distribution rather than the possibility of an ever found in better educated women. The differences expanding tail. among women between our study and the one from Some studies have shown that not only lower edu- Northern Portugal might partly be due to the fact that cated subjects present with higher obesity levels, but the former study was conducted in an urban setting also that this “obesity gap” is currently widening while our data pertains to the whole country. The differ- [10,27,28]. Still, other studies found no such widening ences may also be related with the different methodol- gap [29,30]. In this study, the mean yearly increase in ogy used to measure height and weight (self vs. BMI levels was similar for subjects with primary and measured) instated with the sample basis, since the university level, while subjects with secondary education reporting bias is higher in women than in men and is tended to present a lower yearly increase in BMI levels. dependent of education level. Overall, our data confirm