I don't think there's as much strength behind placebo the way he puts it as he thinks. He criticizes carnivore because there's no placebo. Anyone seen a study where the placebo effect is tested against a placebo?
There is not a placebo effect. What there is, when placebo "works" is an uncertainty. Something in the study design, outside of the targeted intervention, is having an effect. This can be reversion to means. It could be some sort of change in behaviour in the subjects. Is it possible to eat less and lose weight? At least temporarily, yes. Is that a placebo effect, or just a change in behaviour? It's not really a placebo effect, it's not that the little chalk pill or whatever actually has an effect. More likely, something other than the fake drug etc. is having an effect. Placebos disclose that some variable hasn't been controlled for that has an effect--they are a test of the control. There may be cases where it's a matter of "mind over matter," since how we think about something is in fact a stimulus for our metabolism to respond to. But calling that the
placebo effect is not great science.
If there's a "placebo" effect for carnivore--while it's hard to measure, I'd guess it comes down to a few things. (Or rather, effects that a placebo might show exist, if it couldn't actually pin them down). It might work because it's more ketogenic. Also more easily ketogenic, since it's so simple.
It might work because as the Dr. says, it's "ascetic." I wouldn't call it ascetic--but some versions use no condiments at all, not everybody even salts their meat. It's a highly palatable diet, but it's not a hyperpalatable diet in the sense of high variety, high sugar etc. I sort of like to look at this alternately as giving a fairly simple signal to the sensory apparatus of the appetite, do all those flavours make food more palatable, yes, but they also give the brain etc. more work to do to figure out just what we're eating and how much is enough and how much too much.