en Nutrition Nutrition Review Review <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Background and Objectives: </span></span></b>Bread, as a staple food, is a significant part of food waste and a potential threat to food security. This study aims to systematically investigate and quantify the global extent of bread waste and its reasons.<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Materials and Methods: </span></span></b>We searched PubMed, EMBASE, Web of Science and Scopus databases from 1990 to February 2024. We selected observational studies that reported the proportion of bread waste. Random effects models were used to calculate the pooled effect sizes of bread waste.<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Results: </span></span></b>28 observational studies were included in the systematic review and 22 in the meta-analysis, with a sample size of 8,408,344 participants. The pooled size (weighted proportion) of bread waste was 18% (95% confidence interval (CI): 14&ndash;24; I2 = 99.94%, <i>p</i> < 0.002). Proportion of bread waste as a consequence of consumers&#39; practices and beliefs estimated with pooled effect size 24% (95% CI: 21&ndash;28; I2 = 95.2%, <i>p</i> < 0.001) compared with retailers and producers&#39; activities pooled effect size 14% (95% CI: 10&ndash;18; I2 = 98.2%, <i>p</i> < 0.001).<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:115%"><span style="tab-stops:409.5pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:11.0pt"><span style="line-height:115%">Conclusions: </span></span></b>Bread waste prevalence was high, which is due to the behaviors of consumers and retailers. Therefore, community food and nutrition education are prescribed.<span style="font-size:11.0pt"><span style="line-height:115%"></span></span></span></span></span></span></span> Bread waste, systematic review, consumer behavior, meta-analysis 19 36 http://nfsr.sbmu.ac.ir/browse.php?a_code=A-10-1122-1&slc_lang=en&sid=1 Ramesh Allipour-Birgani rallipour@gmail.com 10031947532846006409 10031947532846006409 Yes Tehran University of Medical Sciences Saba Loloei saba.loloei@gmail.com 10031947532846006410 10031947532846006410 No Kerman University of Medical Sciences Sakineh Shab-Bidar s_shabbidar@tums.ac.ir 10031947532846006411 10031947532846006411 No Tehran University of Medical Sciences Hamed Pouraram : h-pouraram@tums.ac.ir 10031947532846006412 10031947532846006412 No Tehran University of Medical Sciences