Weight Watchers announced that its app will now sync with activity trackers Jawbone and Fitbit so that users of the diet and food logging program can see how their fitness data correlates with their nutrition data.

"Losing weight and keeping it off is best achieved by focusing on both eating and activity, and most of us need skills and support to do both," Weight Watchers Chief Scientific Officer Gary Foster said in a statement. "Weight Watchers helps people make better food decisions, and devices and apps monitor activity. Integrating them can equip people with an ideal combination of resources to achieve their goals."

Though the app only integrates with Jawbone and Fitbit so far, the company said they plan to add integration with other popular fitness devices and apps soon. After the trackers integrate their data, the Weight Watcher's app converts the fitness information in PointsPlus values, an existing measure of health based on calories and other nutritional factors. This allows users of Weight Watchers to measure PointsPlus values of nutrition and exercise.

Before the integration, Weight Watchers offered members the option to purchase an activity tracker, made by Philips, to calculate their PointsPlus values. Weight Watchers began offering this activity tracker, called ActiveLink, to its members in late 2012. Since then the company has sold more than 400,000 of the dedicated fitness tracking devices and the service component has about 10 percent penetration into Weight Watchers member base, the company said.

But in a statement Weight Watchers Chief Product Officer Catherine Ulrich said that the company chose to integrate popular activity trackers in part because they wanted to bring flexibility and personalization to the program.

"We know that some of our members are already using monitors like Fitbit and Jawbone, and they'll appreciate being able to see their activity seamlessly tracked within the Weight Watchers experience," Ulrich said. "We also look forward to welcoming a broader community of users to Weight Watchers where they can access the full suite of support, advice and tools to support their weight loss goals."

During its quarterly conference call in May, Weight Watchers CTO Dan Crowe said he wants the company to “become a strong player in the API economy.”

"The great commercial success of our weightwatchers.com products led us to behave as an incumbent and as a result we were slow to adopt the technology capability that is required to meet changing consumer expectation and compete in the digital era characterized by mobile, social, connected devices and open API," he said at the time.

Weight loss startup Wello, which was acquired by Weight Watchers this year, also offers integration with Jawbone.