You've vowed to improve your diet, but then one day you can't help yourself. You start staring at the luscious slice of chocolate cake in the pastry case of your local café. You've been so good, but it just looks so tasty.

Will cracking and indulging just this once lead you down a dark spiral of  guilt and further naughtiness that ends with you on the couch deep in a bag of Cheetos? Or, on the other hand, if you give in to your understandable urge, will your need for chocolate be sated, allowing you to resume your healthy-eating plan with even more commitment?

Thankfully, science recently took a break from splitting the atom and battling dread disease to tackle this admittedly less critical but all too common question. And I have good news for you--it's come down on the side of the occasional naughty cheat.

All-or-nothing goals are more likely to fail.

In a series of experiments, Dutch marketing professor Rita Coelho do Vale and her team compared the success of people on two different types of diets. One group got the usual plan of all-week restricted calories, while the other cut back slightly more for six days and then got the OK to indulge on the seventh. Who fared better?

"Those who were on the diet with one planned naughty day per week managed to sustain stronger feelings of self-control across the dieting period, they found the whole experience more enjoyable, and they reported more sustained motivation," reports the British Psychological Society Research Digest blog. "They also lost just as much weight as the other participants who were on a traditional diet with no planned naughty days."

In short, the occasional indulgence not only feels nicer than constant self-denial (big shock there) but it actually makes it more likely you'll reach your goal. 

What's the takeaway, according to the study's authors? "Abstinence and inhibition of certain behaviors or products frequently leads to 'irresistible urges' and cravings that are difficult to restrain. This may lead to the breakdown of self-regulation and a snowballing to complete loss of control. The present findings indicate a straightforward and new technique for effective self-management," they write. They call this technique "planned hedonic moments."

Let's translate that into normal English, shall we? Basically, constantly denying yourself makes cravings worse and therefore harder to resist. If you give yourself a breather occasionally--as long as it's planned, rare, and in service of the overall mission--you'll be more likely to stick with your goal in the long term.

So go order than slice of chocolate cake already. Science says it's a good idea.