More gravy? Another spud? What harm can it do, we ask, as we squeeze another morsel on to an already heaving plate. The answer, sadly, is quite a lot.
Shockingly, two-thirds of us are already overweight or obese and the average British woman is 1st 7lb (9.5kg) heavier than in the Sixties. Men have piled on 1st 9lb (10.5kg). The reason, it seems, is spiralling portion sizes.
The portion sizes you should be sticking to at any one sitting are shown in the pictures. And of course, they're always much smaller than you think...
The size of a chicken portion should be the same size as a bar of soap.
Don't exceed the size of a pack of cards when you're eating red meat, such as steak.
A piece of oily fish should be the same size as a mobile phone.
For cooked pasta, imagine the size of a tennis ball to estimate the correct portion size.
Fill a coffee mug with dry cereal to get an indication of the size of a portion of dry cereal.
Is the size of your piece of bread no bigger than a five pound note? If so, it's the right size.
Imagine the size of a lightbulb when doling out portions of fruit.
Fill your glass with greens, not wine, to get an idea of how many green vegetables you should be eating.
Chocolate and make-up are some women's weaknesses - use one to signify the size of the other.
Judge the number of raisins you should be eating by the size of a matchbox.
Measure your nut butter by the dimensions of a golf ball and your portion size will be correct.
Is the potato you're planning on eating the same size as a computer mouse? It should be to be the right size.
Find out if the amount of butter you're eating is correct by measuring it against the size of a die.
A cupcake that's the same size as a make-up compact is the correct size for a portion of cupcake to be.
A portion of nuts should be the same size as a book of six stamps.
Find out how much popcorn you should be eating by measuring it against a roll of sellotape.