You can have 10 kg of coal or 10 kg of greenhouse gases and ash. Guess what gives you more potential calories?

Bacterias split lactose to grow, consuming energy in the process and dissipating it as heat and runaway gases.

Some parts of the milk are discarded when making cheese.

Some being all that delicious whey. Whey chock full of protein! Discarding is optional of course.

You can make several different types of cheeses from whey too (with other stuff). Boiling milk, cream and whey gives you Scandinavian style "brunost" (brown cheese), traditionally mainly made from goats milk, or you can make "prim" (soft spread; not usually considered a cheese) if you add more fluids. Both very sweet.

The conversion process consumes lactase, a sugar that's responsible for a significant part of the calories available in milk. Thus, eating cheese is not calorie equal to the volume of milk needed for it's production.

> Lactase

Lactose :)

This is the fundamental point of the article... Enzyme on/off.

The weight difference is water. But if you loose a third of the calories when converting to cheese then I assume they're in the whey. I doubt that people who were hard up for calories would discard the whey unless they had some cultural objection or superstition.

That may be part of it, but another large part of the difference is that, as previously stated, turning milk into cheese destroys lactose. You get fewer calories from the cheese because microbes already used up some of the calories that were originally in the milk in order to turn it into cheese, and thus those calories are no longer available for you.

> I doubt that people who were hard up for calories would discard the whey unless they had some cultural objection or superstition.

Indeed, Norwegian goat cheese is a whey cheese, made by boiling milk, cream and whey leftover from other production (such as more usual casein based cheese). There are a number of other traditional whey cheeses from other countries as well.