Taste and smell are good indicators and stimulators of appetite, but what about your other senses? As anyone who has ever dined in a fancy restaurant can tell you, the attractive appearance of a plate of food can trigger an appetite!

"Your eyes are the gatekeeper to your mouth," says Dr. Wendy Wismer, associate professor in the department of agriculture, food and nutrition science at the University of Alberta. "They set up a lot of expectations and all of your other senses respond based on those expectations. When you look at a food, you might make some evaluations about the intensity of the flavour or the type of flavour, the sound that it might make -- whether it's crunchy or soft."

It makes sense that we expect food that looks visually appealing to taste good, too, but is there more to the theory of colour and its effect on our appetite? Yes, say proponents of colour psychology.

In fact, marketing and nutritional science professor Dr. Brian Wansink maintains we eat with our eyes, and that our eyes are quite capable of duping our stomachs. In one study, Wansink gave one test group 10 M&M's colour choices, while giving a second test group only seven colours. The test group with 10 choices ate 43 per cent more than their counterparts. The perception of more variety (even though the candies all tasted the same) encouraged people to eat more.

Does that mean we shouldn't introduce variety into our diets if we want to keep our caloric intake down? No, says Dr. Wismer. "You still want to treat yourself, even if it's only a hundred calories, or low-fat cheese and crackers. If the food is nicely presented and garnished, it will feel like a satisfying eating experience. You want to make those few calories that you're going to consume look like a full eating experience."

Marketing experts know colour has the ability to stimulate or repress appetite, and can use that knowledge to work to their benefit and, possibly, to the detriment of our waistlines.

Think about your favourite fast-food haunt. Chances are the dominating colours are reds, oranges, and yellows, all colours colour practitioners say stimulate appetite.

Blue, on the other hand, suppresses appetite, perhaps because there are no naturally occurring blue foods. Even blueberries are more purple than blue.

Dr. Wismer cites a research study where the colour of a food and its perceived intensity of flavour were examined. "A lot of food products, including bacon and cheddar cheese, were manufactured in blue. Test subjects were given the blue food, and then the normally coloured counterpart to try. The blue food was always perceived to be less intense in terms of flavour."

As an interesting footnote, Wismer says, "If your foods are coloured inappropriately, it will be more difficult to identify the flavour. An experiment that we often use is to take flavoured water, say cherry-flavoured, colour it green and then ask people to identify the flavour. It will be more difficult for people to recognize that it's cherry flavoured than if it were coloured red."

Read about 10 ways to cheat your cravings.