## 4 Discussion
### Controlling for Systematic Bias across Weekday versus Weekend 24-h Dietary Recalls  
The origin of differences reported in energy and carbohydrate intakes, specific to the second recall, and to the fourth recall, respectively, is not clear. Such differences could reflect true variation in intakes. However, the second to fourth 24-h recalls were performed for each individual on different days of the week, with no obvious reason to consider that such differences could arise from a different distribution between weekends and weekdays. Our analysis indicated that these differences could not be determined by the distribution of weekends in the first two recalls; however, the fourth recall had a significantly higher proportion of weekends than the other recalls. Furthermore, we did not identify differences in nutrient intakes between weekends and weekdays (Table 3). Similarly, studies performed in other countries reported that the day of the week had little impact on the variance of reported values [4; 28]. Recently, [PERSON] et al. discussed many causes of misreporting and measurement errors in self-administered 24-h recalls [6]. In this study, efforts were made to minimize this bias by ensuring specialized training performed by one experienced tutor. Nevertheless, the first recall was performed during a face-to-face visit, while the others were performed via telephone. The validity and relative reliability of face-to-face versus telephone 24-h recalls were found to be similar in several older studies [30; 31; 32; 33], but more recently, [PERSON] et al. [34] noticed, using a web based method for measuring intake versus face-to-face interviews, higher reported intakes in the web-based method. Several publications have presented higher levels in attentional bias from food cues in individuals with overweight and obesity compared to normal weight individuals. Most of the results are consistent with the possibility of the attrition of attentional bias through several types of interventions including the modified food Stroop task, visual dot-probe tasks, the attentional network task and one-back visual recognition tasks, and even passive picture presentation [12]. In our sample, after the enrolment visit and first reporting of the 24-h recall, a reduction in food cues endogenous activation, leading to a reduced intake of food after this timepoint, while an effect of unknown duration might be another explanation of our findings. Although the weekend/weekday discrepancies had been considered in previous studies on children [35; 36], young women [37], middle life women [38], or the general population [39], to the best of our knowledge, this assessment has not been previously conducted in people with obesity, when looking at the differences between the order of recalls. Several publications agreed that weekend diet was lower in quality for both men and women [40; 41; 42]. The trend observed in men (Table 3) was similar to other results already published, suggesting that weekend intakes were higher than weekday intakes, but not necessarily reaching statistical significance [38; 39; 40]. For females, no difference was observed between weekdays and weekends, a result that is in contrast to results published in other studies, possibly suggesting cultural differences [38; 39]. Controlling for Systematic Bias across First Time versus Repeated and Face-to-Face versus Phone Call 24-h Dietary Recalls  
The differences reported in this study (Table 2 and Figure 1) between the first and second recalls and first and fourth, suggested a possible bias that required in-depth investigation. The exclusion of the first recall led to a decrease in the mean reported of several nutrients, but not for energy, nor macronutrients when compared to averages across all four recalls, with small size effects. The alternate exclusion of the second and fourth recalls led to an increase in mean reported energy and intakes for many nutrients when compared to averages across all four recalls, with small or small to medium size effects.