When food hasn't travelled far, at any stage, it usually tastes better and is more nourishing.

The requirements of mass production (which may at least partially be profit from mass production?) impose restrictions that have a direct effect on the quality of the food on your plate.

At what point does the change in quality affect the nourishment available?

Our view is that the apparent "expensiveness" of small scale food production is in fact just an illusion. Higher quality food is better for you, more nourishing & more filling.

Compare, for example, bacon. Most supermarket bought bacon "cooks down" to about half it's original size, unlike most directly sold bacon (I can really only speak for our own I suppose) which retains its original size.

The industrial bacon curing process usually uses salt water forced through the meat. Unsurprisingly this leaves a lot of extra water in the meat, which then evaporates when you cook it.

Dry cured bacon (for example) retains it's original size when cooked.