Plate waste of adults in the United States measured in free-living conditions

We analyze food-item level data collected from 50 adults from the United States using the Remote Food Photography Method® to provide the first estimates of plate waste gathered from adults across multiple consecutive meals and days in free-living conditions, and during laboratory-based meals with fixed food items and quantities. We find average plate waste in free-living conditions is 5.6 grams (7.7 kcals) per item and that 3.3% of all food selected is returned as plate waste, where the percent waste figure is substantially lower than previously published plate waste estimates gathered primarily from dine-out settings in the United States such as buffets and institutional settings with limited-choice meals (e.g., school cafeterias). Plate waste from the same participants during the laboratory-based meals is significantly higher with an average of 203.2 grams of solid plate waste per meal (531.3 kcals) or 39.1% of the food provided, which is similar to the plate waste percentages found reported in some school cafeteria settings. The amount of plate waste generated in free-living conditions is significantly positively associated with portion size selected for an item. In a multivariate analysis that controls for macronutrient profile, items selected from the vegetables, fats/oils/dressings, and grains categories are associated with significantly greater amounts of plate waste per item. We find no significant associations between free-living plate waste and gender, age, race or body mass index but find that women leave more plate waste in the lab meal where portion sizes are pre-determined by the researcher and similar for all respondents. We discuss possible implications of these findings for programs focused on reducing plate waste and food waste among consumers.

本研究采用远程食物摄影法（Remote Food Photography Method®），收集了美国50名成年人的单份食物层面数据，首次针对成年人在自由生活环境下连续多顿餐食与多天的餐盘食物浪费（plate waste）情况，以及食物种类和分量固定的实验室餐食中的餐盘浪费情况，提供量化估计。研究结果显示，自由生活环境下的平均单份餐盘食物浪费量为5.6克（7.7千卡（kcals）），受试者所选食物中共有3.3%最终成为餐盘浪费；该浪费占比显著低于此前已发表的、主要基于美国外出就餐场景（如自助餐）及选择受限的机构供餐场景（例如学校食堂）得到的餐盘浪费估计值。同一批受试者在实验室餐食中的餐盘食物浪费量则显著更高：每顿餐食的固体餐盘浪费平均为203.2克（531.3千卡（kcals）），占所提供食物总量的39.1%，这一占比与部分学校食堂场景中报道的餐盘浪费百分比相近。自由生活环境下产生的餐盘食物浪费量，与单份食物的选取分量呈显著正相关。在控制宏量营养素构成（macronutrient profile）的多变量分析中，从蔬菜、脂肪/油脂/调味酱以及谷物类别中选取的食物，其单份餐盘浪费量显著更高。本研究未发现自由生活环境下的餐盘食物浪费量与性别、年龄、种族或身体质量指数（body mass index）存在显著关联，但发现女性在实验室餐食中产生的餐盘浪费更多——此类餐食的分量由研究者预先设定，且所有受试者的餐食分量统一一致。本研究最后讨论了上述研究结果对面向消费者的餐盘食物浪费与整体食物浪费削减项目的潜在启示意义。