Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of health and wellness products retailer GNC Holdings (NYSE: GNC) climbed 11% in early Wednesday trading after its quarterly results and guidance easily topped Wall Street expectations.

So what: GNC's first-quarter beat was so wide -- adjusted EPS of $0.60 versus the consensus of just $0.49 -- that investors have no choice but to raise their growth expectations yet again. In fact, same-store sales and online sales combined rose a solid 15.8%, reinforcing optimism over the strong health and wellness trends working in GNC's favor.

Now what: Don't expect the sales momentum to let up anytime soon. GNC now sees 2012 adjusted EPS of $2.05 per share on revenue of $2.37 billion, which is also well ahead of Wall Street's view of $1.92 and $2.31 billion. Unfortunately, with the stock busting through its 52-week high -- now up a whopping 115% over the past year -- and trading at a 30-ish P/E, it's only going to be harder for GNC to keep impressing Wall Street.

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