Eat food. Not too much. Mostly plants. That, more or less, is the short answer to the supposedly incredibly complicated and confusing question of what we humans should eat in order to be maximally healthy.

If it came from a plant, eat it; if it was made in a plant, don't.

In general, science journalism concerns itself with what has been published in a handful of peer-reviewed journals - Nature, Cell, The New England Journal of Medicine - which set the agenda.

There's a schizoid quality to our relationship with animals, in which sentiment and brutality exist side by side. Half the dogs in America will receive Christmas presents this year, yet few of us pause to consider the miserable life of the pig - an animal easily as intelligent as a dog - that becomes the Christmas ham.

The issue of snacking is complicated. In principle, "grazing" is probably a good idea. It would even out the insulin spikes and things like that from eating large meals. The problem is it makes it harder for people to control the amount they're eating.

Don't eat anything your great-grandmother wouldn't recognize as food. Don't eat anything with more than five ingredients, or ingredients you can't pronounce.

When you go to the grocery store, you find that the cheapest calories are the ones that are going to make you the fattest - the added sugars and fats in processed foods.