Panera Bread (NASDAQ:PNRA) seems to be one of the main beneficiaries of the fall of Atkins. Today was no exception, with investors bidding up shares after Panera reported what sounded like a pretty hefty same-store sales increase last month.

Today, Panera said that same-store sales increased 8.9% in July, a very impressive figure. As good as that same-store sale gain sounds, it's worth mentioning that Panera's same-store sales gain was a mere 1.6% in the year-ago quarter, making July an easy comparison.

Since I did mention Atkins in my opening paragraph, it's worth noting that last year at this time, Atkins had fully reached fad status and was just about on its way out. (Many of us suspected the demise was coming, since all fads fade, but Fool contributor Nathan Slaughter called it quite accurately.)

Panera has had a good stretch in 2005, especially in terms of investor sentiment. If you recall, earlier this month Nathan examined Panera's quarterly earnings report, observing that for all the company's positive signs, its share price looked a little overdone. Investors have enthusiastically jumped on the carbohydrate turnaround bandwagon in recent months.

A quick check shows that shares of Panera are trading nearly 8% higher today. Not to undermine its recent success, but Panera stock has risen 63% since its low points last year, and soon it will face tougher comparisons. Given its consistent upward tick, maybe investors should consider the old adage that it's not always good to fill up on bread.

Alyce Lomax does not own shares of any of the companies mentioned.