Nutrisystem (NTRI) had a better-than expected first quarter, which sent its share price soaring. The company closed April at $22.02 before moving steadily up in May on the strength of its earnings report to finish May at $27.14, a 23% change, according to data provided by S&P Global Market Intelligence.

Image source: YCharts.com.

What: The weight loss brand had a great Q1, reporting an 18% top-line increase while also saying it was on track to achieve its third consecutive year of double-digit revenue growth. The company raised its forecast for the full year. It now expects 2016 revenue in the range of $517 to $532 million, compared to the previous prediction of $505 to $525 million, while it forecasts earnings per share (EPS) between $1.03 and $1.13, up from a range of $0.95 to $1.05. CEO Dawn Zier discussed the results in Nutrisystem's first quarter earnings release.

The Nutrisystem brand continues to resonate well with customers. Turbo10, Turbo shakes, and new flexible options drove better-than-expected first quarter results...We continue to execute on our strategic initiatives and believe our investments in new products and further enhancements to the customer experience have us well positioned to achieve our third consecutive year of double-digit revenue growth.

So what: Nutrisystem has been a steady performer while rival Weight Watchers (NYSE: WTW) has been much less consistent. That may be because while Weight Watchers has been caught up in the excitement of Oprah Winfrey buying a stake in the company, Nutrisystem has steadily focused on results, product mix, and customer satisfaction.

The company has also consistently spent on product development, with plans for a summer 2017 version of its South Beach Diet and continued refinement of its Shake360 brand.

Now what: The company must continue to sustain their success, which it has shown the ability to do well. CFO Mike Monahan also discussed plans for a share buyback program.

Due to the continued growth in our business and the strength of our balance sheet, we are announcing our board's authorization of a $50 million stock buyback. This gives us the flexibility to continue to invest in the Company's long-term strategy and take advantage of market conditions to further enhance shareholder value.

Nutrisystem clearly has a plan, and it has steadily executed it rather than going for a short-term fix. That suggests the company should be able to deliver on its promises during the rest of 2016.