Building off what Magingus said, I think Sherlock probably eats more when he's not on a case.  He mentions that digestion slows him down on a case, but other than that I'm sure he eats more regularly.  
Also like Magingus said, there are instances where he is eating in the show.  He's eating chips before Mary tells him about the skip code.  One of the shots of him trying to guess John's middle name is at the breakfast table.  There's probably some other examples but those are the only ones that come to mind at the moment.
Sherlock does do a lot of running around after all.  If he never at anything he wouldn't be able to maintain that, and the brain does need food to function.

Okay, I suppose that makes sense. What I read suggested that he only ate on Wendays and when I did a google search to look more into that I found a few other sources that pointed in that same direction. Like you said, something about digestion slowing him down. But thank you, the sources I read it from clearly had a missinturpitation of something or other.

Don't forget he's eaten most of a dish of pasta in that scene in the cafe after he was shot in HLV (when Magnussen eats the olive off his plate).

In the ACD stories Holmes eats quite frequently, despite saying he never eats when he's on a case because digestion slows his brain down.

Last edited by ukaunz (September 20, 2015 3:58 am)

A part of me imagines that when Sherlock is without a case, and he has those bouts of boredom and lethargy, he actually eats quite a bit. People tend to eat when they're bored, even if they're not hungry. 

He does eat, becaude obviously, we've seen him eat. He pretty much demolished that pasta in the scene with Magnussen, and they're pretty big portions (I know because I've had one from the same place!).

He just doesn't eat very much when he's working, but this whole "Sherlock doesn't eat" thing is more of a fanon than a canon. People have kind of ran with it in fan fics and stuff, but it's not actually true.

Canon Holmes eats quite frequently in the ACD stories. I had to laugh when I read this in The Valley of Fear:

He [Holmes] had spent the whole afternoon at the Manor House in consultation with his two colleagues, and returned about five with a ravenous appetite for a high tea which I had ordered for him. "No confidences, Watson; for they are mighty awkward if it comes to an arrest for conspiracy and murder."
"You think it will come to that?"
He was in his most cheerful and debonair humour. "My dear Watson, when I have exterminated that fourth egg I shall be ready to put you in touch with the whole situation. I don't say that we have fathomed it—far from it—but when we have traced the missing dumb-bell—"

He's right in the middle of a case, too... Although a few paragraphs later:

He sat with his mouth full of toast and his eyes sparkling with mischief, watching my intellectual entanglement.  The mere sight of his excellent appetite was an assurance of success; for I had very clear recollections of days and nights without a thought of food, when his baffled mind had chafed before some problem while his thin, eager features became more attenuated with the asceticism of complete mental concentration.

Last edited by ukaunz (October 4, 2015 5:49 am)