Objective: To analyse changes in food choices, diet-related risk factors and their association during 6 months of military service.
Design: Longitudinal cohort study in Finland, where all men are liable to military service and a clear majority of each age group completes service. Dietary intake data were collected by self-administered questionnaire before and at 6 months of service. Three dietary indices based on food frequencies were developed to characterize the diet: Sugar Index, Fibre Index and Fat Index. Thirteen diet-related risk factors were measured at the beginning and at 6 months of service.
Setting: Military environment, two geographically distinct garrisons.
Subjects: Male conscripts aged 18-21 years (n 256) performing military service.
Results: During 6 months of service, positive changes concerned more frequent use of fibre-rich foods (P = 0·011), improved body composition (BMI, waist circumference, muscle mass, fat mass and percentage body fat, P ≤ 0·003 for all), decreased systolic blood pressure and increased HDL cholesterol (P < 0·001 for both). Negative changes concerned more frequent use of sugar-rich foods and increased total cholesterol, TAG and blood glucose (P < 0·001 for all). The consumption of fibre-rich foods was inversely associated with anthropometric risk factors at baseline and with sugar-rich foods at both time points.
Conclusions: Despite more frequent consumption of sweet foods, military service with a unified, nutritionally planned diet, a controlled environment and high physical load has a positive effect on conscripts' health risk factors. The negative changes in blood lipids and glucose may reflect more varied free-time eating.