The British Heart Foundation has warned that the average person in Britain could consume the equivalent of half a pack of lard in saturated fat, and as much salt as would be found in 50 packets of crisps on Christmas Day.
In a survey, the charity asked 2,000 people who celebrate Christmas what they eat and drink over the festive period. For many people, the Christmas indulgence starts before the turkey is even in the oven, it found.
A full English breakfast will be eaten by more than one in 10 on Christmas morning, while 14 per cent will instead choose a bacon sandwich.
The average fried breakfast contains around 1,200 calories, and a bacon sandwich with brown sauce can contain more than half an adult's recommended daily salt allowance.
Almost three quarters of those surveyed said they eat a traditional turkey dinner on 25 December. The typical Christmas meal, including trimmings, adds up to 660 calories.
More than half of half of people said they would follow dinner with Christmas pudding, with 23 per cent planning to have dollop of cream.
Between meals, 40 per cent said they snacked on nuts and 30 per cent on crisps, both of which are often contain added salt. A third of people will eat at least one mince pie, and over half enjoy chocolates throughout the day.
Combined with overindulgence at mealtimes, sweet snacks bring the average person's Christmas day sugar intake to the equivalent of 32 teaspoons.
One in 10 people said they drink more than 13 units of alcohol, the equivalent of 13 shots of whisky in one day.
After breakfast, lunch and dinner on 25 December, the British Heart Foundation estimates that the average Briton could have consumed up to 64g of saturated fat, more than double the recommended daily allowance for men, and three times that for women.
Too much saturated fat can raise a person's risk of developing heart disease, type 2 diabetes and high blood pressure.
Nearly a quarter of people surveyed admitted that they do absolutely no exercise over the entire Christmas period.
The charity recently launched its free 'New Year, New You' packs, containing a range of leaflets with advice on quitting smoking, healthy eating and exercise.It hopes to encourage people to adopt healthier lifestyles in order to lower their risk of developing heart disease.