Apple CEO Tim Cook says the Apple Watch helped him lose 30 pounds

"You know, the watch has been an incredible move into health, in the wellness and fitness piece," Cook told CNBC's Jim Cramer.

"For you, too?" Cramer asked.

"Yes, for me too. I've lost 30 pounds- partly to my watch," Cook said.

Cook has always been a fit and slim guy. He wakes up at 4am every morning to hit the gym.

But Apple is lately keen to emphasize the health and fitness aspects of its wearable gadget.

Late last year, Apple refocused the marketing for the Apple Watch around health and fitness, and Apple said last quarter that the sales of its smartwatch had doubled since the year-ago quarter.

And there are rumors that the Apple Watch might go even farther into the medical world, possibly with a built-in glucose monitor.

Here's how Cook explained how the Apple Watch helped him personally lose weight:

Because it motivates you, and it constantly gives you feedback, it constantly gives you rewards. And this makes a difference over time. And I'm getting calls and letters from so many people where the watch has made a difference in their life. And this is why we are in business. We're in business to help people achieve their objectives, to empower them to do great things.

You can't argue with results. "You're looking good," Cramer told Cook.