Rip Esselstyn, in his book My Beef With Meat, said this about eating in moderation:
“The problem is that there are some things that should be abstained from completely. Whoever tells you it’s okay to have a moderate amount of cocaine, or a moderate amount of heroine? A moderate amount of time sitting next to radioactive waste probably isn’t very good for you either. Nor is moderate exposure to lead paint.”
You might argue that meat* does provide some nutrition. He listed several reasons why the costs of getting that nutrition by eating animal food outweigh the benefits. He concluded:
“Another argument for dropping the moderation mantra is that by continuously feeding your palate these addicting foods, you are never allowing yourself to lose your craving for these foods. … Everywhere I go, people tell me they could never give up their cheese, their steak, their ice cream or whatever because they love them too much. Is this love or abuse?”
I would be hesitant lumping meat with more, and certifiably addictive substances. But by drawing that comparison, he compels us to consider why we continue eating foods that are harming us.
Moderation has much to recommend it. But I think people lean on the phrase to justify eating foods they like but that aren’t especially healthful, especially in more than moderate quantities. Everything we eat does not have to be healthful, but how do you define “moderation”? Once a year, a month, a day? One pack of cigarettes a day may be smoking in moderation to someone who normally smokes 3 packs a day, but it’s still not good for you.
* He includes dairy in this term meat, e.g. “liquid meat (milk), congealed meat (cheese), runny meat (yogurt), mottled meat (cottage cheese), and frozen meat (ice cream).”