The study shows that on average an extra 2,410 calories a day will be consumed during the Christmas period.
We all love a big plate of Christmas dinner and with turkey, roast potatoes, pigs in blankets, parsnips, sprouts, gravy and more, this one plate can add up to 4,350 calories, with alcohol, pudding and all the lovely nibbles adding a lot more.
The LighterLife Fast study also found that on average, we will wolf down four mince pies, three pieces of Christmas cake and two portions of Christmas pudding over the week and many people admitted that they would not get their recommended amount of fruit and vegetables but turn to treats instead.
Dr. Kelly Johnston, head of nutrition and research at LighterLife Fast said: "The run-up to Christmas is a hectic time for most people."
"It's that time of year when trying to maintain a healthy diet is easier said than done, especially when party food and sweet treats are readily available."