It had been more than a month since Craig Boynton had last seen Steve Johnson, and ordinarily, that wouldn't cause anything to be different in their coach-player relationship. But, then again, Johnson hadn't been living his usual life since the two had last connected, after the Paris Masters in November.

Last November and December, Johnson underwent his most intense off-season to date. The American radically changed everything about his diet – what he ate, how much he ate, when he ate – and dropped 15 pounds off his 6'2” frame.

Johnson, who had been wanting to drop the extra weight for years, weighed nearly 200 pounds when he and Boynton returned from Paris last November. The next time they saw each other again, the right-hander was close to weighing 183 pounds – the least Johnson would weigh during the off-season.

Boynton had been warned that his player was looking different, but the veteran coach still had to do a double take when they reunited. “I was told when I see Stevie you might miss him,” Boynton told ATPWorldTour.com. “And it was amazing the difference... It was like a different person. It was like, 'Where'd Stevie go? Hey Stevie, where'd Stevie go?'”

Friends and family members shared similar reactions with Johnson, who was never overweight by any means. But the consistency in their tones had Johnson wondering about his previous look. “Gosh, was I really fat before or what?” Johnson told ATPWorldTour.com. “It's just kind of funny... My parents noticed it. My fiance noticed it... Guys on the tour, they noticed it.”

Johnson, however, didn't drop the weight for reactions. He slimmed down to give himself a formidable “Plan B” when he has an off-day with his customary go-to shots – his serve and his forehand.

“If I'm not playing well, I can just run for days,” Johnson said. “I can just make balls and work myself back into it rather than knowing I only have a certain amount of moving in me and I have to play a little riskier tennis.”

Dozens of ATP World Tour players might have a similar mindset about their fitness. They might think they can run and play defence if they can't find their forehand or if they clash with the conditions one afternoon. But unless they've put in the off-season work, Boynton said, they're probably lacking total confidence in that plan.

“Now he knows he can do it,” Boynton said of Johnson. “That small difference is just enough to win or lose a match.”

Johnson's weight-loss journey didn't start with confidence, though. It started with pancakes as big as a tire, Boynton said. Johnson was more modest: “the size of my head.” Because what's a good diet without a pre-diet binge?

For about 10 days after Paris, Johnson consumed everything he had avoided during the ATP World Tour season. He devoured pancakes, pouring on the syrup and caking them with butter. For dinner, he'd treat himself to a burger, fries and coke.

“Then it was back to the real world,” Johnson said.

He worked with his trainer, Christian LoCascio, who, years ago, helped American Mardy Fish drop 30 pounds. Johnson also worked with Sunfare, a nutritional company that delivered all the meals and snacks to his door.

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He was limited to 2,000 calories a day for the first two weeks, and he didn't consume any carbohydrates after lunch. His diet was heavy on fish, lean meats and vegetables – think salmon and carrots instead of Italian sausage and pasta – and, most importantly, it was portioned correctly. Johnson could have snacks – grapes, slices of turkey – but no nuts. “What I was putting in my body was exactly what it needed to be,” he said.

After the first couple weeks, he upped his intake to 3,000 calories a day and stayed at that level for another month as the weight slipped off.

“I feel like I'm in the best shape I've ever been in,” Johnson said. “I've taken a really big interest in keeping my body as healthy as possible, because trying to play 10 months a year is ideal. If you can play 10 months, if you can play the whole season, that's going to give you a better chance to have a good year.”

Johnson's diet and regimen are more laid-back now that he's in the midst of another ATP World Tour season. He eats non-delivered food, and he doesn't measure every portion to make sure it's the appropriate amount. He's gained a few pounds, too.

“I have to eat normal food and have enough in the body to go play four, five hours,” he said.

But Johnson has never felt better, and he's committed to keeping the weight off and seeing how a lighter – and sometimes unrecognisable – version of himself can perform on the ATP World Tour.

“I'll see how I feel this year and see how the body feels all the way through and maybe make some adjustments or try it again in the off-season,” Johnson said. “But that's just what we do as athletes. We poke and prod and tinker, until we find what works best for us.”