a) It still doesn't say precisely how food consumption is estimated.
b) However it does say this: "The food consumption refers to the amount of food available for human consumption as estimated by the FAO Food Balance Sheets. However the actual food consumption may be lower than the quantity shown as food availability depending on the magnitude of wastage and losses of food in the household, e.g. during storage, in preparation and cooking, as plate-waste or quantities fed to domestic animals and pets, thrown or given away."
-- which explains the implausibly high numbers for some of the western countries; not every calorie bought is a calorie consumed (I know a lot of my food goes off before I get a chance to eat it).