Revenue for the company's third quarter was $348.6 million, down from $365.8 million a year earlier. Analysts surveyed by FactSet expected $352.7 million.
The company, formerly known as Weight Watchers, ended the quarter with about 4.4 million subscribers, up about 5.7% from the comparable period a year earlier but down about 140,000 from the second quarter.
The New York-based company reported third-quarter profit dropped by nearly one-third to $47.1 million, or 68 cents a share. Analysts surveyed by FactSet expected 65 cents a share.
The company's shares, which are down 2.7% so far this year, fell 12% in after-hours trading to $32.88.
Still, WW International affirmed its view of at least $1.4 billion in revenue for the year and raised profit targets to a range of $1.63 to $1.75 a share, from its previous view of $1.55 to $1.70 a share.
The New York-based company has laid out ambitious enrollment targets as it overhauled its programs beyond its traditional dieting business and brought on media mogul Oprah Winfrey.
Ms. Winfrey, who came to the company's rescue in 2015, is one of the company's largest investors and a board member. She has emerged as WW's most public face, sharing with fellow WW members the highs and lows of her efforts to eat healthily and manage her weight.
Chief Executive Mindy Grossman said company officials expect recruitment growth to accelerate in the current quarter and retention trends, now just over 10 months globally, to continue to improve.