If you're immediately muttering 'killjoys!' at this page, you've discovered exactly why Christmas is the season of added pounds. All rules go out the window – food you’d never eat at any other time of year enters your home in huge quantities, and eating Quality Street before breakfast becomes the norm.

In fact, one study by nutritional supplement brand Forza found that only 3% of people don’t overdo it at all between Christmas and New Year, while a saintly 18% let themselves indulge only on the big days like 25 December and New Year’s Eve and, yes, you guessed it, the rest of us go mad for the whole festive season.

‘We have an emotional relationship with food at Christmas, but it’s not your job to eat badly and drink loads,’ says James Duigan, trainer to stars like Elle Macpherson and author of new book Blueprint For Health (Pavilion, £14.99). ‘I used to gorge myself and feel awful; now I know when to stop.’ It takes minutes to eat the 500 calories in a slice of Christmas pudding with a generous dollop of brandy butter but, on average, almost an hour of running or more than 90 minutes of walking to burn it off.

So how can you enjoy the seasonal treats you love without gaining pounds that hang around for ages? Try these top tips…

1. Define your festive food goals

‘Telling yourself you just want to be good over Christmas is not going to help you stay on track, but creating a specific goal will,’ says weight-loss coach Lizi Jackson-Barrett. ‘Decide what really matters to you. Will you enjoy one treat a day? Will you be active three times a week to offset the Christmas pudding? Pick something realistic and stick to it.’

2. Appreciate that a little still tastes good

In fact, the first two or three bites of Christmas pudding taste better than the next four, five or six, so just have a little of what you fancy. ‘It’s nice to have traditions, but you don’t have to eat to the point where you feel sick,’ says James Duigan.

3. Psych out the buffet

Experts at Cornell University in the US who studied how to eat less at a buffet made some interesting discoveries. It helps if you’re not sitting facing the food – out of sight is out of mind – and, when you do go to fill up, choose a small plate so you can’t put much on it. Assess everything that’s on offer, choose your five favourite things, then fill the rest of the plate with salad. When you sit back down, put a napkin on your lap to add formality – the more we ‘respect’ a meal, the more filling it seems.

4. Use visualisation

If you feel your willpower starting to slip, Lizi Jackson-Barrett suggests imagining the outcome of a lapse. ‘How will you feel in January with that extra weight? What clothes will you wear, and how will you look? Be as detailed as you possibly can. Now reverse the exercise and imagine in a similarly detailed way what will happen if you don’t give in. Understanding which feels better should keep you focused.’

5. Turkey is your friend

As are fresh prawns, cold chicken, ham off the bone and anything else that’s high in protein and low in fat. ‘High-carbohydrate foods like pastry-loaded canapés, roast potatoes, biscuits or sweets send your blood sugar soaring and trigger cravings for more. Eating enough protein should lead to fewer cravings,’ says nutritional therapist Zoë Stirling.

6. Healthy choices start in the supermarket

‘If you don’t buy biscuits or chocolate, they won’t tempt you,’ says James Duigan. ‘Don’t get things just because you always have done; ask, ‘Do I really want all of this, or will I end up eating it for the sake of it?’

7. Greens, greens, greens and more greens

‘Cabbage, broccoli, Swiss chard, watercress and kale should feature daily in December,’ says Zoë Stirling. ‘They’re low calorie, high in filling fibre, and support the liver in its detoxification process.’ This last point is important because, if your liver is tackling alcohol, it can’t burn fat as effectively. Why not give it a helping hand?

8. Be a healthier host

‘You might not have control over anyone else’s Christmas fare but, if you’re the one hosting, you can serve houmous and crudités, quinoa chips with freshly made dips, and chicken drumsticks instead of pastries,’ suggests James Duigan. After all, there are plenty of other parties where people can get their sausage-roll fix!

9. Get back on that wagon

So you slipped up and ate all the (mince) pies – and a bit of the chocolate gateau, too? In the words of the suitably wintry movie Frozen, let it go. ‘Don’t see it as a reason to write off the rest of the day,’ says Lizi Jackson-Barrett. ‘Chalk it up as one bad decision, and ensure your next one is something you’re happy with.'