To verify the association between changes in socio-economic level (SEL) and nutritional status of Chilean adults over a 10-year period.

Concurrent cohort study.

Individuals born from 1974 to 1978 in the Valparaíso Region of Chile were evaluated between 2000 and 2002 (n 1232) and again between 2010 and 2012 (n 796). SEL was characterized according to the occupation and educational level of the head of household. Nutritional status was based on measurement of BMI and waist circumference (WC).

Between the first and second evaluation there was a 13 % reduction in the number of individuals classified as poor and a 12 % increase in those classified in the medium high SEL. Increases in BMI were found among women who remained in the low SEL (β=2·2, 95 % CI 0·16, 2·87) compared with women who maintained the same SEL (and whose SEL was above low over the 10-year period). Women who remained in the low SEL increased their WC (β=4·10, 95 % CI 0·27, 7·93). There were no associations between nutritional status and SEL among males.

In the period studied, the SEL of the study population improved between the third and fourth decade of life, but BMI and WC also increased among women, with the lowest socio-economic group experiencing the greatest changes. Meanwhile, among males we found no association between anthropometric measurements and changes in SEL.