Development and validation of a Food Choices Score for use in weight-loss interventions

Abstract

Weight loss results from an energy deficit, although the quality of food choices making up the diet may also be important. The aim of the present study was to develop and validate a diet quality tool based on food categories to monitor dietary change in clinical weight-loss settings. The Food Choices Score (FCS) was based on seventeen food categories, each scoring up to five points, totalling 85. In addition to content validity, the tool was validated using (1) two energy-deficit diet models (6500 and 7400 kJ) assuring nutrient and food-group targets and (2) dietary data from two weight-loss trials (n 189). First, the diet models confirmed that an optimal score of 85 was achievable. Second, change in scores was compared with weight loss achieved at 3 months. The trial data produced a mean FCS of 42·6 (sd 8·6), increasing to 49·1 (sd 7·6) by 3 months. Participants who lost weight achieved a higher FCS at 3 months than those who did not (P= 0·027), and there was an even greater improvement in the FCS (P= 0·024) in participants losing ≥ 5 % body weight than in those losing < 5 %. A greater change in the FCS (Δ ≥ 7) resulted in a greater change in BMI (P =0·044), and score change was correlated with weight change (P= 0·023). Participants with the highest scores ( ≥ 56 v. ≤ 44/85) consumed more fruit (P< 0·001) and low-fat dairy foods (P =0·004), less fatty meat (P< 0·001), non-whole-grain cereals (P< 0·001), non-core foods and drinks (NCFD) (P< 0·001), less energy (P =0·018), less dietary fat (P< 0·001) and more dietary fibre (P= 0·013). Weight loss was 35·5 % less likely to be achieved with every increase in the serves of NCFD (P =0·004) in the study sample. The FCS is a valid tool for assessing diet quality in clinical weight-loss settings.