Leave a light on at night and you could pile on pounds, according to latest scientific research.
Boffins at Ohio State University in the US have discovered that mice exposed to dim light at night-time gained a third more weight than mice who were kept in the dark, even though both sets of mice had the same activity levels and food intake.
The only difference was that the mice who were exposed to light at night started to eat at different times. When the food was restricted so they had to eat at the usual times, weight gain stopped.
For those struggling to lose weight, it seems like the most unlikely diet tip ever; knock off all the light sources when you go to bed and invest in a pair of heavy curtains. But it's by no means the only strange diet advice that's emerged over the last few years as the weight-loss industry grows ever fatter on our desperation to stay trim.
Here are some of the weirder findings of the latest research.
Get a good night's sleep
Most of us know that if we eat less and take more exercise we will lose weight. It should follow therefore that if we sleep less, we should be thinner. But a study published recently in the Annals of Internal Medicine, showed that dieters who cut back on sleep reduced their fat loss by 55%.
They also felt hungrier and produced higher levels of ghrelin, a hormone that triggers hunger and reduces energy expenditure.
Go to a doctor who can empathise
According to a survey by the Duke Medical Centre in America, doctors spend on average about 15% of their time talking to patients about diet and exercise. But the success of the doctor's intervention depended on the way they communicated.
Patients of doctors who talked about dieting in a motivational way lost 3.5lbs within three months of their visit. Those whose doctors were judgmental lost nothing. Turn off the TV and computer
Studies have shown that people who spend hours in front of the computer or TV are more likely to be over-weight, even if they exercise regularly. The Ohio State University study suggests that the problem may be that these people are eating at irregular times, perhaps later at night when the body does not have time to metabolise the food.
Ditch the credit card
People who use credit cards to pay for their shopping are more likely to buy unhealthy food, according to a study by Cornell University and the State University of New York.
"Cash payments are psychologically more painful than card payments, and this pain of payment can curb the impulsive responses to buy unhealthy food items," say the study's authors.
Find a magic potion
At the National Meeting of the American Chemical Society in August, scientists unveiled the results of a startling new clinical trial which showed that dieters who drank two eight-ounce glasses of a mystery potion before meals, lost on average 5lbs more in three months than those who didn't. The mystery potion? Tap water.
Until recently there was no scientific evidence suggesting that the slower we eat, the less we consume. In fact a study in the early '90s suggested there was no connection between fast-eating and weight gain. But that's changed with two separate studies. The first at Rhode Island University showed that people who ate a bowl of pasta quickly consumed 646 calories. Those who were encouraged to pause between bites and chew well consumed just 579 calories.
And a study published in the Journal of Clinical Endrocrinology and Metabolism showed that people who ate an ice-cream over 30 minutes had higher levels of hormones that trigger satiety than those who ate the ice-cream in five minutes.
Take a gamble
The latest dieting fad in the US, and more recently the UK, is 'bet dieting'. Dieters join a website and promise to lose a certain amount of weight within an agreed time-scale.
If they fail, money is taken from their accounts and paid to a charity of their choice, and a group email is forwarded to their friends detailing their failure.
US fans claim the scheme has a success rate of 85%. But Professor Richard Ashcroft, of the Centre for the Study of Incentives in Health in the UK, queries whether such an approach is effective in the long run.
"The problem is once the incentive scheme has finished we don't know if they carry on being successful after that," he says.
Read food labels
Just looking at food labels can lead to weight-loss according to a study published in the Journal of Consumer Affairs in the US. People who examine food labels and do not exercise are more likely to lose weight than those who exercise but do not pay attention to food labels.
Women between the ages of 37-50 years are more likely to read food labels than men, and are therefore more likely to lose weight, according to the study.
See a shrink
Did your mother give you sweets when you were upset as a child? Are you repressing a traumatic incident involving a chocolate biscuit as a toddler? The psychology of weight-loss is now big business. Supporters claim that our failure to lose weight is more often the result of psychological problems than nutrition issues.
Approaches vary widely. A motivational expert will help set realistic goals. A psychologist will look at the reasons why someone over-eats. A psychoanalyst will bring a patient right back to childhood to uncover the source of eating problems.