'Tis the season for excess.

Before the end of the week, I will attend three final Christmas parties, eat copious canapés (instead of real dinners), and be too hungover on weekdays to properly exercise. Next week, it'll be Christmas ham sandwiches all week, Champagne and Aperol Spritzes, and maybe no working out at all.

How much weight will I have put on between now and the end of the year? Let's find out.

Research has found that the average person might consume up to 500 calories more per day over the holiday period, accumulating to an extra 6160 calories over the five days before, during, and after Christmas Day.

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It sounds like a lot until you consider that each tiny Christmas mince pie you munch on this week is up to 300 calories apiece.

What's the result of all of this eating to excess? The average weight gain is 0.9 kilograms – barely enough to register on the scales, but a gain nonetheless. At the top end of the scale, around 1 in 10 people will gain about 2.3 kilograms.

With that in mind, will the average person actually get rid of this holiday weight, or does it just stick around their middle into 2019? The research says they will keep it.

A study in the New England Journal of Medicine found that adults usually still weigh more in February and March of each year than they did in September and October of the previous year. This suggests that we put on extra weight over the holidays, and don't do anything about it. Perhaps most concerningly, that study found that come September of the new year (i.e. September 2019 in this case), most people's weight won't have changed much from their post-holiday gains in February/March.

Here's the crux of all of this, then. For any holiday weight you put on before the end of 2018 – whether it's 0.9 kilograms or more than two – the odds are stacked against you for losing it in 2019. It's highly likely that little bit of extra weight will stick around all of next year.

Your chances of entering 2019 heavier than you are today are therefore pretty high. Is there anything you can do to prevent it?

The answer is yes, and there's even research out there uncovering how people who successfully manage their weight over the holiday season do it. In a nutshell, people who are strict with their holiday eating efforts, eat breakfast every day throughout the holiday period, and pre-plan their holiday food intake and exercise are the most likely to lose and maintain and extra weight gained.

The people at the most risk of holiday weight gain are those who are formerly overweight or obese. Most people struggle with food around Christmas, but this group in particular has a hard time.

Everybody will benefit from planning their holiday food intake and exercise output now (like, today) and sticking to it more carefully that you would during the rest of the year. This isn't about depriving yourself – you're still going to be on holiday after all – but more about being conscious of what you consume, and what you burn off, by tracking it all.

As noted, breakfast every single day is key in keeping your weight down before the year is out – even on those days you know you have a big lunch just hours later. This will help prevent excessive consumption via energy-dense foods during the day. If you keep your protein intake high, you'll also feel fuller for longer.

Perhaps most importantly, I think the best way to keep on top of your weight for the rest of your year is to do it with a buddy. If you have one other person who is equally keeping tabs on their holiday intake (be it your best friend or your mum), the associated groupthink will help you stomach the whole season a lot easier.