enough 作表语时，其主语通常应该是表示数量或隐含有数量意义。如：
Five minutes is enough. 五分钟就够了。
A day or tzoo is enough. 一两天就够了。
Four copies is enough. 四册就够了。
Eight hours of sleep is enough. 八小时睡眠足够了。
One glimpse at himself in the mirror was enough. 让他照着镜子瞧上自己一眼就够了。
I met him only the once, and that was enough. 我就见过他那一次，那就让我受够了。
She did it just the once, and once was enough. 她只做了这一次，而一次也就够了。
I must double the amount, or it won’t be enough. 我必须把数量增加一倍，不然会不够。
而网友的句子中 the food 并非表示数量或隐含有数量意味，所以不是很合适。但如果改成下面这样的句子，则完全可以：
Two kilos of food is enough.
Two baskets of food is enough.
Three bags of food will be enogh.
My food together with his food should be enough.
