Food for thought: Comparing self-reported versus curbside measurements of household food wasting behavior and the predictive capacity of behavioral determinants

•Household food waste may be underestimated if self-reported.•An objective method to collect household food waste samples was tested.•Households self-reported 6.63 portions/week and disposed 2,783 g/week of food waste.•How food waste data is collected impacts relationships with behavioural determinants.•A poor understanding of food waste disposal can impair intervention development. A survey, based on an expanded Theory of Planned Behavior (TPB), was used to indirectly measure self-reported food wasting and its behavioral determinants. This was complemented with directly and objectively measured food waste in curbside garbage samples. Households (n = 189) reported throwing out avoidable food waste a mean of 5.48 times (SD = 5.58) and 6.63 portions (SD = 6.61) the week prior to completing the survey. These same households threw out a mean of 2,783 g/week of food waste (SD = 2,664) in a curbside garbage sample, with 63.27% of this consisting of avoidable food waste. There were weak to fair correlations between self-reported and curbside food waste samples. The direction and level of significance of all correlations of TPB behavioral determinants with self-reported and curbside food waste samples were similar, although the correlation coefficients were higher for self-reported food wasting. A linear regression (R2 = 0.34, p