Comedy and wellness duo The Gavin Sisters have revealed their top tips to staying healthy at Christmas. Sharon and Lauretta Gavin from North London, who run The Detox Barn wellness retreats, know only too well how it feels to have an over-indulgent Christmas that you live to regret. “We’ve been there,” said Sharon. “There were many years in the past when we ate, drank, over-did it in every way at Christmas and actually, because of that we didn’t enjoy it as much as we could have done. We’ve realised since then that there are some simple steps we can take…