A woman eating chocolate.

Milk chocolate might not be the first food you think of when you decide to go on a diet with its reputation of being high in sugar, fat and caloric content.

But starting your day with chocolate could actually have 'unexpected benefits' by helping your body burn fat, scientists have discovered.

Researchers at Brigham and Women's Hospital in Boston, US, gave 100 grams of milk chocolate to 19 post-menopausal women within one hour of waking up and one hour before they went to sleep for two weeks.

Results found that the chocolate intake made no difference in the participants' weight and actually aided weight loss.

It said that eating chocolate in the morning can actually help burn fat and reduce glucose levels in the blood.

This may possibly be due to flavanols, beneficial chemicals found naturally in cocoa that increases fat oxidation.

Whereas eating chocolate at night helped to regulate sleeping patterns and alter metabolism.

Over the course of the trial, participants were allowed to eat "any other foods" including sweet treats, aside from their milk chocolate diet.

Frank A.J. L. Scheer, a neuroscientist with the division of sleep and circadian disorders, said: "Having chocolate in the morning or the evening/night results in differential effects on hunger and appetite, substrate oxidation, fasting glucose, microbiota (composition and function), and sleep and temperature rhythms.

"Our findings highly that not only 'what' but also 'when' we eat can impact physiological mechanisms involved in the regulation of body weight."

The researchers added: "Results show that females were less hungry when eating chocolate and had less desire for sweets than with no chocolate, especially when taking chocolate during the evening/night.

"Moreover, daily cortisol levels were lower when eating chocolate in the morning than at evening/night."

However, chocolate should still be eaten in moderation as part of a balanced diet.

The new study, published in The FASEB Journal, follows other recent research into the potential benefits of eating cocoa, the primary ingredient in chocolate.