TABLE 1.

Subgroup analyses for total energy intake (energy content of the supplement plus energy consumed at an ad libitum test meal), according to protein form, type, timing, quantity, type of control used, and gender analysis in healthy older adults

	Number of comparisons	Mean difference, kJ	95% CI	Heterogeneity (I2), %	P	P value for subgroup difference
Total energy intake	22	649	438, 861	56	<0.00001
Protein form						0.66
Liquid	15	685	369, 1002	62	<0.0001
Semi-solid/solid	7	592	332, 852	42	<0.00001
Protein type						0.40
Whey protein	13	561	242, 880	54	<0.001
Protein through diet/whole foods/other	9	745	463, 1027	59	<0.00001
Protein timing						0.02
Alongside meal	3	295	23, 567	0	0.03
≥60 min before ad libitum test meal	19	730	485, 976	57	<0.00001
Protein quantity						0.18
≤30 g	18	576	371, 782	50	<0.00001
>30 g	4	1133	340, 1925	60	<0.01
Control types						0.01
Water/flavored water	13	899	600, 1197	57	<0.00001
Saline	3	350	−270, 971	0	0.27
Nothing	6	340	110, 569	23	<0.01
Gender analysis						<0.001
Female-only studies	6	340	110, 569	23	<0.01
Male-only studies	10	650	297, 1002	50	<0.001
Both genders	6	1122	834, 1410	0	<0.00001