According to the Centers for Disease Control, more than one-third of American adults are seriously overweight, roughly double the percentage 25 years ago.

The most obvious cause of this epidemic is the inexpensive availability of tasty treats composed of empty carbs, marketed incessantly. Homo sapiens had evolved over several hundred thousand years to eat as much as possible when food was available, since it ­usually wasn't.

Is our current social ­networking revolution creating a similar epidemic of "Information Gluttony"?

Are we carrying invisible spare tires of Virtual Cheetos around with us? There is ­serious reason to think so. Social networking has gained a place of prominence in everyday American life that is ­staggering.

According to "The Information Diet: A Case for Conscious Consumption," a 2011 book by Clay Johnson, "the modern human animal spends upward of 11 hours out of every 24 … gorging on information … Just as we have grown morbidly obese on sugar, fat, and flour — so, too, have we become gluttons for texts, instant messages, e-mails, RSS feeds, downloads, videos, status updates, and tweets." (This incredible number rings true if one includes TV, radio and music.)

Let's consider the ­practical utility of three of the most popular social networking platforms — Facebook, Twitter and LinkedIn. How would you perform the same activities without a computer? How productive would they seem without their technological wizardry? See my handy chart to estimate your return on investment in social networking sites.

My personal usage of each platform is idiosyncratic and not useful to generalize from. (When the Mall of America opened 20 years ago, I recall predicting confidently that it would close within a couple of years, because "why would anyone travel a long distance to a mall just because it is four times the size of the local one?")

I am a power user of Linked­In, with about 1,500 connections, most of whom I actually know (not surprising for an executive recruiter).

I tweeted consistently for about a year, until my account was hacked and my contacts spammed. I also am dubious about becoming too dependent on anything with the word "twit" in it.

As for Facebook, I have had an account forever, but resist spending much time on it.

Nevertheless, it seems reasonable to predict that Linked­In will continue its healthy growth, and may turn into the Amazon of professional ­networking and job search.

Facebook's growth may stabilize (Facebook usage is reportedly going down among kids).

And Twitter? Who knows? Twitter answers to a different drummer — the need to yammer.

About the author: Isaac Cheifetz is president of Open Technologies, a Minneapolis-based executive search and talent strategy consultancy for information and IT industries. Reach him at isaac@opentechnologies.com or on Twitter at @isaaccheifetz.