Table 3.

Direct weighing for food waste studies in the National School Lunch Program^a

	Reference
	Jansen and colleagues, 197833	Davidson and colleagues, 197934	Comstock and colleagues, 198235	Getlinger and colleagues, 199636	Whatley and colleagues, 199637	Adams and colleagues, 200538	Toma and colleagues, 200939	Hoffman and colleagues, 201040	Lazor and colleagues, 201041	Chu and colleagues, 201142	Hoffman and colleagues, 201143	Cohen and colleagues, 201244	Yon and colleagues, 201245	Cohen and colleagues, 201346	Ramsay and colleagues, 201347	Byker and colleague, 20145	Cohen and colleaugues, 201448	Hunsberger and colleagues, 201449	Jones and colleagues, 201450	Jones and colleagues, 201451	Cohen and colleagues, 201552	Miller and colleagues, 201553	Wilkie and colleagues, 201554
Study design	Qb	CSc	CS	Ide	If	CS	Ie	If	CS	CS	Lg	CS	MMh	CS	Q	CS	Ie	MM	Ie	Ie	RCTi	Ie	CS
Specific data collection method	DWjk	DW	DWk	DWk	DWl	DWm	DWk	DWk	DWk	DWk	DWk	DWk	DWn	DWk	DWk	DWk	DWk	DWk	DWo	DWo	DWk	DWk	DWp
Type and no. of schools
Elementary	29	23	11	1	2	4	1	4		12	4		9		1	1	4q	1	1q	1	7	1	1
Middle									5	3		4		4							7
High	29									2													2q
Grade level	5 and 10	1–3	1–5 or 6	1–3	3–5	1–5	Kindergarten-6	Kindergarten-1	NRr	NR	Kindergarten-1	NR	3–5	6–8	K	Prekindergarten-Kindergarten	1–8	Kindergarten-2	Kindergarten-8	1–5	3–8	Kindergarten-5	Kindergarten-12
Average percent wasted for dietary components measureds
Grains/bread	21		◇t	18			◇			35		◇			◇
Vegetables	51		◇	16		◇		◇			◇	◇		73	◇	51	67	◇	◇	◇	73	◇
Fruits/fruit juice	30		◇	12		◇		◇			◇	◇		47	◇	33	43	◇	◇	◇	36	◇
Meat/meat Alternate	18		◇	18					◇						◇
Milk	9		◇	82								75	◇	25	◇	46	41	◇
Other	32u	◇uv	◇	2	◇v		◇u		◇v			18u		19u		51u	20u	◇u			27u		◇
Days of food waste data collectionw	10	NR	33	8	76	4	7	36	NR	NR	60	8	9	8	4	5	16	5	23	64	84	3	20
No. of waste observationsx	130,000	230	13,749	NR	560	294	NR	1,414	1,933	NR	1,060	3,049	793	3,049	473	304	1,030	261	180	251	2,638	2,027	NR
Effective public health practice project quality rating10	Weak	Weak	Weak	Moderate	Moderate	Weak	Moderate	Moderate	Weak	Weak	Strong	Moderate	Weak	Moderate	Moderate	Weak	Strong	Strong	Moderate	Moderate	Strong	Strong	Weak

^aData were collected to assess food waste after new school lunch meal patterns implemented beginning 2012.

^bQ=quasiexperimental.

^cCS=cross-sectional.

^dI=intervention.

^ePre-post intervention.

^fPre-post-follow-up intervention.

^gL=longitudnal.

^hMM=mixed methods.

ⁱRCT=randomized controlled trial.

^jDW=direct weighing.

^kDifference weight of plate waste for each food minus weight of average selected serving.

^lPercent plate waste calculated by dividing the weight of edible food waste by the mean serving weight.

^mDifference weight of plate waste for each food minus pre consumption selections for all students’ plates.

ⁿWeight of fluid milk remaining was determined using the full weight and empty container weight of the carton.

^oFruit and vegetable consumption was calculated by weighing all produce prepared and subtracting unserved and waste weights, divided by number of students.

^pWaste was sorted by hand and weighed on a digital scale.

^qAt least one study school was not identified as elementary or middle, but identified kindergarten through eighth grade or was not identified as middle or high, but identified as grades six through 12.

^rNR=not reported with specificity.

^sIn some cases, the average percent waste within a dietary component was reported within the cited article. In other cases, this study’s authors calculated average percent wasted within a dietary component when research design collected waste across multiple intervention periods. When percent consumed was reported (instead of percentage waste), this study’s authors calculated average percent waste by subtracting the percent consumed from 100% and, if necessary, averaged across multiple intervention periods or groups.

^t◇=study indicated dietary component measured but not average percent wasted within dietary component.

^uMeasured waste of a mixed entrée.

^vSpecific macro- and/or micronutrients measured in whole meal.

^wData calculated as number of days reported for study multiplied by number of schools involved in food waste collections.

^xData reported according to study as individual food items or entire student tray.