Objectives To evaluate whether four types of low-cost interventions in the working environment can promote the small everyday lifestyle adaptations that can halt the epidemics of obesity and hypertension when maintained long term.

Design A single-blind uninterrupted time-series intervention study consisting of four study periods: run-in (2 weeks), baseline (2 weeks), intervention (2 weeks), and after intervention 2 weeks).

Setting University Medical Centre with over 11 000 employees, over 1000 hospital beds and over 2000 customers visiting the hospital restaurant each day.

Participants Hospital staff and visitors.

Interventions (1) Point-of-decision prompts on hospital elevator doors promoting stair use. (2) Point-of-purchase prompts in the hospital restaurant promoting reduced-salt soup. (3) Point-of-purchase prompts in the hospital restaurant promoting lean croissants. (4) Reversal of the accessibility and availability of diet margarine and butter in the hospital restaurant.

Main outcome measures (1) Number of passages through 15 different parts of the hospital staircases. (2) Number and ratio of normal-salt and reduced-salt soup purchased. (3) Number and ratio of butter croissants and lean croissants purchased. (4) Number and ratio of diet margarine and butter purchased.

Results Elevator signs increased the mean 24-h number of stair passages per measurement site (baseline: 992 ± 479 on week days and 208 ± 116 on weekend days) by 11.2% (95% CI 8.7% to 13.7%). This effect was maintained at least 2 weeks after the point-of-decision prompts were removed. Point-of-purchase prompts promoting low-salt soup and lean croissants did not result in altered purchase behaviour. The ratio between the purchase of margarine and butter was changed sevenfold (p<0.01) by reversing the positions of these products in the hospital restaurant.

Conclusions Healthy lifestyle adaptations in the working environment can be effectively promoted by making healthy choices easier than unhealthy ones. Educational prompts at points-of-decision moderately increase stair climbing, but do not affect healthy food choices.

Protocol registration Clinicaltrials.gov identifier number: NCT01574040.