Goldman Sachs analyst Jason English upgraded WW International (WW) to Buy from Neutral with a price target of $48, up from $26. The company formerly known as Weight Watchers closed Monday up $1.57 to $34.55.

A "powerful inflection" in subscriber growth should drive a positive estimate revision cycle and re-rating for the stock, English tells investors in a research note. The analyst believes WW's subscriber growth will be driven by its new program called myWW, aggressive TV and social media campaigns, and the co-branded Oprah 2020 Vision tour. His analysis indicates the company's efforts are driving interest higher, and he expects subscriber growth to accelerate to 14% in 2020.

At the current share price, the risk/reward skews favorably and represents an attractive entry point, says English.