Pork has gone from being "the other white meat" to a low-carb staple for millions of delighted eaters over the past year. This widespread diet shift has benefited companies like Smithfield Foods (NYSE:SFD), which have leveraged the skyrocketing hog industry and ridden their share prices to all-time highs.

Smithfield reported its fourth-quarter earnings today of $0.64 a share, which blew away the analysts' consensus estimate of $0.51 and pummeled last year's number of $0.04. The company sees live hog prices and pork demand remaining strong through the remainder of its next fiscal year, a trend that it began to leverage successfully in its current fiscal year.

Smithfield has also concocted a new bacon strategy, which will quickly make the company a net buyer of pork bellies. The company is planning to increase bacon production capacity by 20%, or 100 million pounds, even though it already derives about 60% of its total revenues from pork sales. Smithfield also has turned around its beef operations, which were profitable for the first time in quite a while.

The low-carb craze also lit a fire under such companies as Hormel Foods (NYSE:HRL), Tyson Foods (NYSE:TSN), Sara Lee (NYSE:SLE), and Pilgrim's Pride (NYSE:PPC), which have all benefited from the Atkins diet phenomenon.

But fad diets tend to fade away, so the Atkins low-carb diet might be nearing its maturity stage over the next six months to a year. We all know what happens after the maturity stage of the product/fad life cycle: a decline -- anyone still on the grapefruit diet? I'm all for companies taking advantage of favorable market conditions, but I'm also very wary of trends that can shift as quickly as America's love affair with pet rocks.

Smithfield shares are currently trading at 14 times the $2.17-per-share EPS expectation for fiscal 2005. With a 10% EPS growth rate expected over the next five years, with the higher growth occurring over the next few years, the shares are approaching a fairly valued state. If you have completely bought into this pork frenzy, watch your back; one day, you could turn on the news or pick up a newspaper and be informed that fatty foods are once again bad for your health.

Are you giving the low-carb diet a shot? Share your experiences on our Low-Carb Way of Life discussion board.

Fool contributor Phil Wohl spent over 12 years on Wall Street and now concentrates his writing on more fictional characters. He has no stake in any firms mentioned above.