Scientists have discovered a "gluttony gene" that may be responsible for obesity cases caused by compulsive non-stop eating.
In laboratory tests on mice, researchers discovered the Bdnf gene mutation failed to transmit the message to the brain that signals when the body is full.
The researchers hope the findings, published online in the journal Nature Medicine, could help with the treatment of obesity.
"This discovery may open up novel strategies to help the brain control body weight," said lead researcher Dr Baoki Xu, from Georgetown University Medical Centre in the US, as cited by the Press Association.
Two key hormones, leptin and insulin, release chemical signals that activate neurons in the hypothalamus region of the brain to signal when the body is satiated.
In the mice that had a mutation of the Bdnf gene, the neurons were not activated and therefore their food cravings continued. As a result, the mice ate twice as much as those without the mutation.
"If there is a problem with the Bdnf gene, neurons can't talk to each other and the leptin and insulin signals are ineffective, and appetite is not modified," said Dr Xu.
"Short" versions of the Bdnf gene block the leptin and insulin signals and prevent the "stop eating" message passing through the brain to the correct appetite-suppressing locations, say the scientists.
Previous studies have shown that mice without a 'long' version of this gene also suffered from memory impairment.
A link has also been previously identified between Bdnf mutations and obesity in humans.
Dr Xu said the next step was to look into the development of drugs that stimulate Bdnf activity in the brain.
"We have opened the door to both new avenues in basic research and clinical therapies, which is very exciting," he added.
Prof Sadaf Farooqi, who studies the relationship between genes and obesity at the University of Cambridge, told the BBC: "Genes have a surprisingly large role, it's often underestimated. Between 40 and 70% of the difference in weight between two individuals is due to genetics."
However, she added that the gene mutation is "very rare" in humans.
Doreen Virtue, author of <em><a href="http://www.amazon.co.uk/Constant-Craving-What-Cravings-Overcome/dp/1848505906" target="_hplink">Constant Craving</a></em> offers her advice on how to resist your salt, sugar and fat cravings and stay on the right track with your diet.
"Ginger ale and soy milk are high in tyramine, which can help relieve chocolate cravings. Pekoe tea is high in chocolate's other stimulating ingredient. theobromine."
"One reason we shun fruit during our sweet cravings is that fruit seems like a deprivation alternative. We've got to dress fruit up! Put a little flavoured, fat-free yoghurt on top. Puree the fruit with an ice cube and some ginger ale. Microwave sliced apple for two minutes at high temperature with a little bit of cinnamon and you've got a quick, low calorie apple-pie type treat."
"If, after analysing your cravings, you discover any anger, frustration or stress, ask yourself how you might take even one step toward alleviating the source of these emotions. Is there someone you can talk to, or some changes that you can make in your life? If you reduce the source of your uncomfortable emotions, you won't need to crave sweet things anymore."
If we tell our bodies that this chocolate bar or hamburger will be our last treat ever, we're more likely to binge. "It's like we're seeing a beloved person for the last time, so of course we want to spend as much time as possible with that object of affection." The key is eat all treats in moderation and if the craving get too much, seek healthier alternatives.
"Crunch on crisp vegetables dipped in low calorie, fat-free salad dressing. Instead of potato chips and french fries, go for carrot and celery sticks. Broccoli and cauliflower florets are also tasty replacements. They may not seem as appealing as the fatty versions, but the crunch and flavour will soothe your craving."
"Sweet treats usually equal reward. We all need pats on the back and kudos for hard work. But instead of stopping at the cookie shop or take-out, why not treat yourself to a new book, item of clothing or shoes? This will feel just as satisfying and is much healthier than a fat-laden treat."