The ex-American actress has banned him from drinking tea and coffee while the former hellraiser is already off booze in support of his pregnant wife.
The British Royal is heading for his first dry 'New Year' as his wife looks to reform him in 2019.
And now she has also persuaded him to remove caffeine too in preference for mineral water as she tries to persuade him to get healthier.
It seems to be working because he looked lean and fit as the pair went to church over Christmas.
Meghan's new health plan seems to be paying dividends with friends claiming that Harry is 'more relaxed' that before.
A source told The Sunday Express Newspaper: "Considering he's been a drinker since he was a young teenager, it's quite an achievement.
"He was always fidgeting and on the go, always looking for the next thrill. He was a great laugh but it was always very full on."
"Now his new regime doesn't make him the most entertaining party guest in the world, but he's definitely more chilled and relaxed."
And she and Meghan are encouraging Harry to get healthier in 2019.
The source added: "All she Meghan did was show him there's another way to live and he's become a huge fan.
"He eats well, doesn't poison his body, exercises, does a bit of yoga and is a lot happier."
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