Changes in diet and physical activity in the 1990s in a large British sample (1958 birth cohort)

Objectives: To investigate whether adults studied in 1991 and 1999 (at ages 33 and 42 y) improved their diet and their physical activity level, in the direction of recommendations issued during the same period. Design: Longitudinal 1958 British birth cohort study. Setting: England, Scotland and Wales. Participants: All births, 3rd-9th March, 1958. A minimum of 11 341 participants provided data at 33 y, 11 361 at 42 y. Main outcome measures: Frequency of leisure time activity and consumption of (i) fried food, (ii) chips, (iii) wholemeal bread and (iv) fruit and salad/raw vegetables, at 33 and 42 y. Results: Most people changed their physical activity and dietary habits over the 8-y period. About a third of men and women increased, and a third decreased their activity frequency. Findings for fried food consumption were similar. A significantly greater proportion of cohort members decreased their chips consumption (32%), rather than increased it (17%) and increased their fruit and salad consumption (30%), rather than decreased it (25%). In all, 26% of men and 33% of women consistently ate, or switched to eating mostly wholemeal bread, while 56% of men and 48% of women consistently ate less or switched to eating less. Social gradients were seen for activity and diet in 1991, but associations between social factors or body mass index and change in activity or diet were inconsistent. Conclusions: Lifestyle habits such as dietary intake and physical activity are slow to change. Current health promotion strategies may need to be supplemented with additional methods to affect the desired change in these habits.