Data_Sheet_1_Assessing daily energy intake in adult women: validity of a food-recognition mobile application compared to doubly labelled water.docx

Accurate dietary assessment is crucial for nutrition and health research. Traditional methods, such as food records, food frequency questionnaires, and 24-hour dietary recalls (24HR), have limitations, such as the need for trained interviewers, time-consuming procedures, and inaccuracies in estimations. Novel technologies, such as image-based dietary assessment apps, have been developed to overcome these limitations. SNAQ is a novel image-based food-recognition app which, based on computer vision, assesses food type and volume, and provides nutritional information about dietary intake. This cross-sectional observational study aimed to investigate the validity of SNAQ as a dietary assessment tool for measuring energy and macronutrient intake in adult women with normal body weight (n = 30), compared to doubly labeled water (DLW), a reference method for total daily energy expenditure (TDEE). Energy intake was also estimated using a one-day 24HR for direct comparison. Bland–Altman plots, paired difference tests, and Pearson’s correlation coefficient were used to assess agreement and relationships between the methods. SNAQ showed a slightly higher agreement (bias = −329.6 kcal/day) with DLW for total daily energy intake (TDEI) compared to 24HR (bias = −543.0 kcal/day). While both SNAQ and 24HR tended to underestimate TDEI, only 24HR significantly differed from DLW in this regard (p < 0.001). There was no significant relationship between estimated TDEI and TDEE using SNAQ (R2 = 27%, p = 0.50) or 24HR (R2 = 34%, p = 0.20) and there were no significant differences in energy and macronutrient intake estimates between SNAQ and 24HR (Δ = 213.4 kcal/day). In conclusion, these results indicate that SNAQ provides a closer representation of energy intake in adult women with normal body weight than 24HR when compared to DLW, but no relationship was found between the energy estimates of DLW and of the two dietary assessment tools. Further research is needed to determine the clinical relevance and support the implementation of SNAQ in research and clinical settings.
Clinical trial registration: This study is registered on ClinicalTrials.gov with the unique identifier NCT04600596 (https://clinicaltrials.gov/ct2/show/NCT04600596).

精准的膳食评估对于营养与健康研究至关重要。传统膳食评估方法包括食物记录、食物频率问卷以及24小时膳食回顾法（24HR），但均存在一定局限：例如需要经过专业培训的调查员、流程耗时较长，且估算结果存在偏差。为克服上述缺陷，学界已开发出基于图像的膳食评估应用等新兴技术。
SNAQ是一款基于计算机视觉（computer vision）的新型图像式食物识别应用，可识别食物种类与摄入分量，并提供膳食摄入相关的营养信息。本项横断面观察性研究旨在验证SNAQ作为膳食评估工具，在正常体重成年女性（n=30）中测量能量与宏量营养素摄入的有效性，并以双标水法（doubly labeled water, DLW）——一种测量每日总能量消耗（total daily energy expenditure, TDEE）的金标准方法——作为对照；同时采用单日24HR法估算能量摄入以进行直接对照。
本研究采用Bland-Altman图、配对差值检验以及Pearson相关系数，评估不同评估方法间的一致性与相关性。结果显示，相较于24HR法（偏倚=-543.0 kcal/日），SNAQ与双标水法在总每日能量摄入（total daily energy intake, TDEI）上的一致性更优，二者偏倚为-329.6 kcal/日。尽管SNAQ与24HR法均倾向于低估TDEI，但仅24HR法与双标水法的结果存在显著统计学差异（p<0.001）。采用SNAQ估算的TDEI与TDEE之间无显著相关性（R²=27%，p=0.50），24HR法的估算结果同样如此（R²=34%，p=0.20）；且SNAQ与24HR法在能量及宏量营养素摄入的估算值间无显著统计学差异（差值Δ=213.4 kcal/日）。
综上，本研究结果表明，相较于24HR法，SNAQ在正常体重成年女性群体中能更准确地反映能量摄入水平（以双标水法为对照）；但双标水法的能量估算值与两种膳食评估工具的估算值之间均未发现显著相关性。未来仍需开展进一步研究，以明确SNAQ的临床应用价值，并为其在科研与临床场景中的落地提供支撑。
临床试验注册：本研究已在ClinicalTrials.gov平台注册，唯一标识符为NCT04600596（https://clinicaltrials.gov/ct2/show/NCT04600596）。