Watching a nature programme the other day, I was informed that a single walrus can eat 4000 clams in a ten minute dive (Nature's Great Events, broadcast by BBC, Feb. 11 2009) which seems a tad greedy to me, but then look at the size of a walrus. Are they that big because they eat a lot of clams or do they eat a lot of clams to stay that big?

And a diet of thousands clams can't, one feels, do a lot for their digestion. This was borne out by another factoid about their digestive problems given to us by Sir Attenborough, but I won't put you off your food by repeating it here.

I would guess that walruses don't have a particularly emotional relationship with their food. Their strategy seemed to be: get hungry - dive - scoop up as many clams as possible - burp - do it again.

We humans have much more imaginative ways of relating to food. And as we are not restricted to a diet of clams, we can "dive" for lots of different kinds of foods. Presumably at some stage the walrus gets to feel full and will stop his clam eating. But we find it more difficult to recognise our "full" signals or we override them because we want to eat more, or eat a different sort of food or simply have some dessert. We also don't have to expend the same number of calories as the walrus in capturing our food

This is a tricky combination - easily available food, demanding little in the way of exercise to get it and a misunderstanding of hunger/fullness signals. It means we can all overeat easily, or simply make poor food choices.

What to do about it?

Here are some tips that can help.

1. Use a smaller plate. It really does work, the plate looks full and your brain get signals that you are eating a feast. And oh-the-sheer-joy of going back for a (small) second helping if you truly are still hungry at the end of the plate.

2. At the start of the meal plan the foods and courses that you think you will eat. But as you eat, enjoy each mouthful. Don't get trapped into thinking the next mouthful will be better or look forward to the next course so much that you forget to enjoy this one. Do this even with the snacks you eat so that your brain gets a chance to register food and calories before you make the next food choice.

3. Listen to your stomach and listen to your mind. And when they say you have had enough, stop. Ok, you can have one tiny mouthful more, just to make sure. But then stop eating, or your food will become less, not more, enjoyable.

4. When you've eaten what you feel is a good quantity of food, picture the walrus. And 4000 clams. Then ask yourself if you are still hungry.

And be thankful that we have a more varied diet than 4000 clams!