Nike, Fitbit and Jawbone are among the leading makers of smart fitness bands, which sell for between $100 to $200. That price will likely come down as smart bands get smarter and lighter, say analysts.
(Read more: The flabby business of shrinking waistlines)
"They'll continue to improve on not only telling you what you're eating and how you're exercising, but how you're doing physically at any point in time—and maybe alert if you're going to have a heart attack," said Rob Enderle, analyst with Enderle Group in San Jose, Calif.
Enderle foresees tremendous potential for wearables because of the devices' size and functionality.
(Watch: Disrupting fitness through your iPhone)
"They pretty much monitor everything you're doing ... so it gives you the feeling that you're in much more control of the weight loss that you're trying to achieve," Enderle said.
Companies like Weight Watchers will either figure out wearables quickly, or risk becoming obsolete, analysts say.
Hottovy at Morningstar said that [CEO Jim Chambers] has admitted that Weight Watchers missed the boat on the mobility trend, and I think they're very much playing catch-up."
By CNBC's Mark Berniker and Josh Lipton