The author of a new RSC book on the science behind obesity is urging Christmas diners to stack their festive plates high with food.
But, says Dr Claire Allardyce, their eyes should feast on the plate's contents before the fork is lifted.
Scientist Dr Claire Allardyce, writer of Fat Chemistry said today: "The mind has a powerful influence over what we think we have eaten and how satisfied we become.
"Recent research suggests that our memory of a meal is important in determining how full we feel. If our memory is of holding back or half-filling our plates, we are likely to be more hungry in the short-term than if we remember eating our fill."
"Load up your plate, but stick to single servings: When it comes to food maths, the brain has an annoying habit of forgetting second and subsequent servings. If you visualize your whole meal on a plate - take time to look at it in detail - you can help your supercomputer take stock of what you ate.
"And the despondence of depriving yourself of that once-a-year treat may do more harm than good."
Dr Allardyce added: Christmas has been a dieters' nightmare for decades because of the well-known high calorie content of roast spuds, Christmas pudding and the dreaded cheese board, not to forget the more welcome alcoholic accompaniments.
"Christmas may be the one time of year your body gets a good feed. Focus on filling up your plate with vegetables and forget about the calories in your favorite indulgences."
"Enjoying food with family and friends gives a feel-good factor as powerful against weight gain as some of the pills and potions sold over the counter."
But what about the calories? Can we really throw caution to the wind?
Dr Allardyce suggests that we can - if we follow some simple guidelines.
Start with a salad
Studies show a low-calorie salad starter dramatically reduces how much volunteers ate during their main course. On the other hand an energy-dense appetizer - those cheese stuffed potato skins, for example - has the opposite effect.
Be traditional with turkey
Turkey is a low fat meat and delicious if cooked correctly. If you find it dry, go American and soak it overnight in water before roasting it upside down.
Don't be shy with the vegetables
Christmas is a time when there is the opportunity to go to town on vegetables. Cook as many different vegetable accompaniments as you feel able. It is proven that we humans like variety and will eat more when various flavours are on offer. As vegetables are central to good health and weight control, there is rarely such a thing as too much.
Think about condiments
Most condiments are loaded with sugar and salt. Yes it is Xmas, but reducing salt intake was singled out by the World Health Organisation as the educational program that was likely to reap the biggest dividends in terms of world health. Instead, flavour up the meal with lashings of gravy (low salt of course) and loads of vegetables.
Accompany the meal with a high calcium mineral water
Calcium supplements have been shown to help weight loss on a calorie controlled diet, not least because this mineral binds to fat preventing its absorption. Cleanse your palate during Christmas dinner with a glass of high calcium mineral water and you could also be going some way to reduce the calories that enter your body.