Validity and practicability of smartphone-based photographic food records for estimating energy and nutrient intake

Image-assisted dietary assessment methods are frequently used to record individual eating habits. This study tested the validity of a smartphone-based photographic food recording approach by comparing the results obtained with those of a weighed food record. We also assessed the practicality of the method by using it to measure the energy and nutrient intake of college students.

The experiment was implemented in two phases, each lasting 2 weeks. In the first phase, a labelled menu and a photograph database were constructed. The energy and nutrient content of 31 randomly selected dishes in three different portion sizes were then estimated by the photograph-based method and compared with a weighed food record. In the second phase, we combined the smartphone-based photographic method with the WeChat smartphone application and applied this to 120 randomly selected participants to record their energy and nutrient intake.

The Pearson correlation coefficients for energy, protein, fat, and carbohydrate content between the weighed and the photographic food record were 0.997, 0.936, 0.996, and 0.999, respectively. Bland-Altman plots showed good agreement between the two methods. The estimated protein, fat, and carbohydrate intake by participants was in accordance with values in the Chinese Residents' Nutrition and Chronic Disease report (2015). Participants expressed satisfaction with the new approach and the compliance rate was 97.5%.

The smartphone-based photographic dietary assessment method combined with the WeChat instant messaging application was effective and practical for use by young people.