Is the use of ‘Red meat’ for ‘Substance’ very popular? Can I say ‘Your talk doesn’t have any red meat,’ to talkative person?

Solution 1:

You can certainly write “there was no red meat in his talk (proposal)” and be correctly understood to be criticizing the lack of substance.

The term red meat more often has a culinary meaning (edible meat which is red in color before cooking: typically cow, sheep, horse, duck, goose according to Wikipedia) or else functions as a political metaphor. The example you quote falls into the political category. Double-Tongued Dictionary has:

throw red meat v. to appease, satisfy, rally, or excite one’s (political) supporters

This political idiom has a cynical, arrogant air: red meat – a tasty, desirable food – is metaphor for an especially enjoyable tidbit; one throws red meat to one’s animals or to dangerous brutes to reward or appease them. DTD gives examples of usage: “throw red meat to the lions, the wolves, the sharks, etc.”

Google Book Search offers more tasty examples in print:

[T]he Bill goes too far in taking away from the counties various functions in order to give the district councils some red meat to get their teeth into …. (Parliamentary debates, House of Commons official report, 1971)

… Robert Rubin … is not a man even to countenance such discussion except in the strictly political sense of feeding some red meat to Greenberg, Carville, Begala, and the other politicos. (Mother Jones Magazine, Jul–Aug 1995)

Referring to these occasional hard-line policies as attempts to appease domestic audiences, the Echo of Iran observed that Rafsanjani’s “kinder, gentler foreign policy” is not simply “a hoax”. Rather, he and his aides know their preferred policies “rile the radicals” and “feel they must feed some ‘red meat’ to keep them at bay”. (Post-revolutionary Politics in Iran: Religion, Society and Power by David Menashri, 2001)

Barry Popik gives many more examples of the term as it has been used in politics since 1950.

Nevertheless, red meat is sometimes used metaphorically to mean something substantial. The more frequent idiom is plain meat (without the color), but you can locate plenty of examples of the former in printed literature using Google Book Search.

Solution 2:

You're confusing two idioms.

Meat is the substantive portion of anything:

Now we get to the meat of the issue.

Red meat is demagoguery intended to rile up your own audience:

Talk of "you didn't build that" was red meat to the convention audience.

Red meat that isn't intended to be recognized by your opponents is a dog whistle. Your opponents will accuse you of using codewords, when really, of course, what you're saying is the truth and you are speaking truth to power.

Almost anyone interested in American politics will recognize these phrases.

Solution 3:

I think you understand this idiom pretty well, and your sample sentence is spot-on.

Red meat means "real food", or as one says in a similar idiom, "something you can get your teeth into". It is Manly food, Heroick, the sort of thing that Hector and Lysander and HEnglishmen eat, unlike the bland and emasculate fodder vegetable fodder consumed by Scots and Eyetalians or the loathsome amphibians prepared with artsy and effeminate fervor by Frenchmen.

And red meat has, too, overtones of primitive rawness—the flesh our savage ancestors hunted at great risk and ripped, still hot and bloody, from the bone.

In the immediate context, red meat contrasts with the tasteless and textureless pabulum (or perhaps, given the location, grits) which dominates the menu at political conventions and such-like media events.

EDIT: I seem to be showing my age. The answers by Malvolio and Bill Franke represent current usage more accurately than mine, which was based on such uses as this, from Eugene O'Neill:

SID: I suppose Dick is deep in "Nick Carter" or "Old Cap Collier."
MILLER: No, he passed that period long ago. Poetry’s his red meat nowadays, I think—love poetry—and socialism . . .

Solution 4:

"Is it predominantly a political jargon? Can I say ‘There was no red meat in his talk (proposal)’ just casually?"

There was a famous TV commercial in the USA some years ago that went "Where's the beef?" The beef is the heart of the hamburger; beef is also red meat. It means substance, as the dictionary says. I'd say that using red meat instead of just meat in this instance adds the connotation that the convention will be bloody (metaphorically, not actually) and that the politicians will act as savagely as starving sled dogs thrown chunks of raw meat. It's humorous and perhaps a little tongue in cheek. I find it acceptable and appropriate in this instance. As a rule, however, I'd omit the red unless I wanted to suggest a bloody (verbally, that is) battle. I don't think it works as a casual criticism of a vacuous proposal.