By Rebecca Morelle
Science reporter, BBC News, York
Our love of chocolate knows no bounds.
Chocolate seems to have an innate appeal - but is it all in the mind?
We think about it, dream about it, and probably - just sometimes - eat a bit too much of it. Some people even go so far as to claim to be addicted to it.
But what drives our cravings for chocolate?
Some believe it contains mind-bending ingredients that can enhance our moods.
One bite, they maintain, and chocolate's psychoactive compounds cause warm and fuzzy feelings to wash over us, making us want more and more.
But Peter Rogers, professor of biological psychology from Bristol University who is speaking at the BA Festival of Science in York, has carried out research that suggests this is not the case.
Not the culprit
To test chocolate's feel-good power, he gave volunteers some tasteless capsules to swallow.
Some contained cocoa powder, which, because it contains a higher concentration of these mood-enhancing chemicals, should cause a marked effect on the volunteers' disposition; other capsules contained nothing but starch.
Professor Rogers said: "We tested how they were feeling afterwards - did they feel a buzz or an elevated mood after eating the cocoa?
"Naughty but nice" - is this the basis of chocolate's appeal?
"The volunteers did say that they felt a bit more alert and stimulated - but not euphoric. We think any slight stimulation is (down to) the caffeine."
He said that other research had also suggested chocolate's chemical make-up was not the culprit for our lust for the stuff.
"It doesn't stack up," he said.
"A lot of those substances are in other foods that do not have the same appeal as chocolate. Also, the concentration seems too low for them to be having an effect, especially in the UK's favourite type, milk chocolate."
Instead, he suggested that chocoholics were chocoholics because their favourite food was often deemed "naughty but nice".
He explained: "The nice bit is its sweet taste, lovely melt-in-the-mouth texture, and our associations that we have in our food culture - we use it as a gift, a reward and as something to treat ourselves with - which gives it extra appeal.
"On the negative side, it is something we shouldn't eat too much of, it's not a staple food in our diet, it is relatively high in fat and sugar, and therefore potentially unhealthy."
It is this that makes us want it so much. We are wrestling with the desire to eat it because it is so nice; but we restrain ourselves, because we perceive eating it as being naughty.
And this unfulfilled desire, said Professor Rogers, was experienced as a craving, which in turn is attributed to addiction.
Attitudes towards chocolate around the world also backed up this idea that our want for chocolate stems from the values we place upon it, he added.
In the US, he said, a survey of women showed that they mostly craved chocolate at certain points in their menstrual cycle, while in Spain, women said they wanted to eat it most after dinner.
"It is explained by culture and not chemistry," he added.
Tricking the brain
But how can we escape from this chocolate lust that may be all in the mind?
One way, said Professor Rogers, was to try thinking about a piece of fruit each time you thought about chocolate, in the hope that your cravings might transfer to the healthier option.
More realistically though, he suggested that if chocolate consumption was modest, trying to enjoy the experience of eating it rather than feeling bad about it could break the naughty-but-nice cycle.
But if this doesn't work and your hankerings for chocolate feel just too overwhelming, then perhaps some other research presented at the BA science festival may bring a little cheer.
Chemicals in dark chocolate could prove a boost for the heart
Roger Corder, professor of experimental therapeutics at Queen Mary, University of London, has found that eating chocolate can aid a healthy heart.
But not just any old stuff - there is chocolate, and then there is chocolate.
Fresh cocoa beans are a rich source of a type of chemical called a flavonoid, and these molecules have been shown to protect cardiovascular systems.
But by the time cocoa beans find their way into chocolate bars, only a tiny proportion of flavonoids are left. Some are lost through the manufacturing process; and in any case, many products contain relatively little cocoa and relatively large amounts of sugar and fat.
To get optimum heart-boosting effects, the chocolate needs to contain about 75-85% cocoa solids, and about 25g should be eaten a day, the scientist said.
Professor Corder is about to embark on a clinical trial to test chocolate eating's effect on the heart.
He may just find recruiting volunteers for this trial a little easier than normal.