Sure. But 2 months is not long enough. Some unaccounted-for vitamin with a long half-life or a low requirement could give deficiency symptoms after 4 months but not 2.

Also, people on restrictive diets post all the time about how crappy they feel when they reintroduce something. For him to slide comfortably into the explanation "thus my product makes me feel better than restaurant food" is typical of such dieters' enthusiasm.

Although bad restaurant food does exist, much of the digestive upset people experience when going out to eat is simply down to overeating, late eating, or alcohol.

That was also a week he spent travelling. Sleeping away from home, long plane/car rides, irregular schedule, and all the other attendant discomforts are quite enough to throw me off my game, even without dietary shifts.

here's what i was thinking:

1. "real food" has plenty of vitamins and stuff

2. some of that stuff might have a long half-life in the body

3. and be needed only in small (catalytic?) amounts.

so that

1. you wouldn't know about them if you just studied basic nutrition textbooks (or perhaps nobody knows about them)

2. if your social eating is frequent enough, you'd never lack them.

so, ideally, people following some soylent-type practice strictly will develop some interesting symptoms, and we'll discover some new stuff. but if they cheat, we don't learn as much.

i admit there's a good possibility that we already know about all the vitamin-like stuff there is. after soylenters start showing better 10-year mortality, i'll gladly join them.