Development and evaluation of food photograph series software for portion size estimation among urban North Indian adults

BACKGROUND: Accurate population specific aids are needed for food portion size estimation in diet assessment. OBJECTIVE: To develop and evaluate a food photograph series software for accurate portion size estimation among urban North Indian adults. METHODS: A preliminary food consumption survey was conducted on 60 adults (25-60 years, male = female = 30) selected purposively from urban Delhi. A range of portion sizes of commonly consumed food items were standardized and photographed at 45 degree angle. An online portion size estimation tool was developed comprising data on 368 recipes and photographs for 313 food items. Real time (part A) and recalled estimation after 24 hours (part B) was done for pre-weighed food portions by participants (n = 30, 25-60 years, male = female = 15) using the software. RESULTS: The % mean relative error in estimation of 24 pre-weighed food portions was -5 +/- 22.61% and 13.07 +/- 53.22% for parts A and B respectively. Significant correlation between actual and estimated food portions was observed (r > 0.90, p < 0.0001). Correct picture was selected by participants in >= 60% estimations while correct or adjacent picture was selected in >= 89% estimations. CONCLUSIONS: The software is a useful aid for dietitians and other nutrition professionals for accurate portion size estimation among urban North Indian adults.