Change that benefits individuals and organisations while delivering health outcomes and benefits society requires a research focus that extends 'beyond the individual' to environment shapers. A pre-post observational study assessed two food provision structural changes to understand the role food service environments had on food selections. Diners were observed prior to (lunch n = 1294; dinner n = 787) and following (lunch n = 1230; dinner n = 843) structural changes in a buffet-style dining room-including provision of a healthy convenient meal alternative for lunch (healthy lunch bag), and a pleasurable dinner (make-your-own pizza). Food choices shifted with 19% of diners opting for a healthy lunch bag and 29% of diners selecting a pizza dinner, moving away from the existing buffet. Examination of selections by those continuing to select from the concurrent buffet selections established that the availability of healthy alternatives in the buffet partially explained food choices, moderating any observed changes in food selections. The food service sector is a promising avenue through which dietary behaviours can be improved. Further studies, particularly those that measure selections over the longer term, and that include measures of satisfaction and profit, are needed.