One of the most common nicknames for your retirement portfolio is "nest egg," but in the realm of food metaphors, it might be better to think of it like a holiday feast. So many dishes, so many choices, and to be healthy, you need to pick a properly balanced meal -- but also one that suits your personal tastes. So how should one do that? The answer comes under the heading of "portfolio allocation," and it's the focus of this episode of Motley Fool Answers.

In this segment, hosts Alison Southwick and Robert Brokamp take the metaphor into that section of the table reserved for dishes less typically American -- curried lentils or kimchi, anyone? -- and consider whether your portfolio is really balanced if you only own U.S. equities.

A full transcript follows the video.

This video was recorded on Nov. 20, 2018.

Robert Brokamp: So far we have talked about mostly classic American foodstuffs. But if you look at your table, you might see a little bit of influence from other countries and at my family's table, the most prominent, especially for the vegetarians, is macaroni and cheese. It actually has a Greek origin, both the product as well as the name.

Alison Southwick: What? Macaroni and cheese is Greek?

Brokamp: Well, the macaroni part.

Southwick: OK.

Brokamp: The macaroni started with Greece, then moved to Italy. And then in the 1700s in England the term macaroni started being applied to people who were basically dandies. Like they tried to bring European influences to England. Overdress a little bit.

Engdahl: Maybe stick a feather in their hat.

Southwick: Yeah, they stick a feather...

Brokamp: I was just getting to that. So Yankee Doodle originally was written by a British surgeon making fun of Americans who put a feather in their cap and then thought that made them look more sophisticated. But then the Americans were like, "We love it!"

Southwick: We love pasta!

Brokamp: We love it! We're going to embrace it.

Southwick: Yeah, why not?

Brokamp: Now Yankee Doodle is the state song of Connecticut.

Southwick: Oh, really?

Brokamp: As for macaroni and cheese, that started in England and is now very popular in America. So, when it comes to your portfolio this, of course, is your international allocation.

Southwick: I was wondering how you were going to get there. Wow!

Brokamp: We don't have as good stats on international stocks, so for this I'm just going to go back to 1970. Since then international stocks have provided an average 8.9% a year. We mentioned a couple of episodes ago about how many people, like Jack Bogle of Vanguard, think international investing is not necessary. There's certainly no evidence that international stocks outperform U.S. stocks over the long term, plus many U.S. companies have plenty of business overseas, and I generally agree.

That said, I do have significant allocation in my own portfolio, as well as is in the Rule Your Retirement model portfolios. I should finish with the nutritional facts, here, and that's the average annual return of 8.9%. The best year was 70%.

So it's pretty good. Worst year a loss of 43%. What do these overall target-fund date allocations look at? What are those looking at in terms of international stocks? Basically around 28% for non-U.S. developed [so that's Canada, England, Western Europe generally speaking], and then 6-7% emerging markets. So in my little allocation, here, the macaroni and cheese is the developed and the emerging markets are the lentils on your table...

Southwick: Oh, man, I love lentils!

Brokamp: I know you love lentils!

Southwick: Like some curried lentils that your vegan sister-in-law brought. Is that what it is?

Brokamp: Right, something like that. So basically they are looking at allocating more than a third of your stock portfolio to international stocks. Most Americans are not there, and even I have in my allocations closer to like 30%.

The tricky thing about emerging markets is the data for emerging markets, depending on what you look at. There's some data sources that say they outperform all other types of stocks and other data that say they underperform all other types of stocks, partially because the data on some of these emerging markets is not so good and there's some debate on what makes an emerging market; for example, South Korea. Is that an emerging market or not?

Southwick: It feels pretty emerged.

Brokamp: But the thing is if you're going to go international, you're going to get more volatility in the U.S. stocks, and the more you tilt your portfolio toward emerging markets, it's going to get crazy. So keep that relatively small, especially if you're not a particularly risk-tolerant investor.

A few months ago I did a survey of investment return assumptions across many of the major firms. The vast majority expect emerging markets to outperform U.S. stocks over the next decade. There's going to be a lot of volatility along the way and, of course, who knows if that will actually happen in the end.

Southwick: So you have a valid reason for maybe not loading up on lentils and not offending...

Brokamp: I'm just staying you don't need lentils to have a perfectly fine Thanksgiving meal.

Engdahl: Just enough to be polite.

Brokamp: [Laughs] There you go!