How 'cheat days' can actually speed up weight loss by revving up metabolism, according to dietitian

Taking short breaks from your diet could help speed up metabolism leading to more long term weight loss, according to dietitians. 

A break of a day or two could help mitigate the biological detail that causes most dieters to gain weight when they stop a restrictive diet. 

So-called 'cheat days' increase levels of a hormone in the body that helps us burn calories - in other words, keeping the metabolism high.

'Our metabolism slows down as we become smaller, we don't need to burn as many calories,' said Brittany Werner, Pennsylvania-based registered dietitian and founder of fitness coaching firm, Working Against Gravity. 

This makes it easier for a surplus in calories to build up, leading to weight gain. 

And this is why 'drastic calorie reduction does not work long term,' Werner said.

However, eating more for a little while not only retains more muscle mass - which burns more calories - it also 'tricks' the metabolism into thinking it expanding more fuel.

Taking a break from a restrictive diet can reinvigorate you psychologically, Werner told Business Insider. 

Previous studies have shown that when dieters look forward to a cheat meal at the end of the week, their eating habits are better overall, compared to those who keep a strict, unending diet.  

Cheat days 'can really help you break through to hit the next few months,' of your diet and fitness goals, Werner said. 

Also metabolism is a bit like a muscle - it needs to be worked frequently in order to stay highly active, she suggests.

Research shows that when you lose weight, the body doesn’t produce as much of a hunger-regulating hormone called leptin. But cheat days might cause a temporary uptick in leptin, speeding your metabolism up. 

One Swiss study showed that upping calorie intake for one meal could increase the production of hormones that regulate body weight by 30 percent. 

Another study from the University of Western Australia put obese men on two different diets over a four month period - one that involved breaks from the diet and another that did not. The group with breaks lost more weight, on average, than the group without breaks. 

In general, Werner said, if you're losing too much weight too quickly, you might not have enough energy to power your body to make positive fitness changes.

But, key to the concept of the cheat day is making sure you indulge in healthy portions. 

Eating too much of a fun food could be considered binging - a concern that puts many dieters off a moment of indulgence.

Werner recommends being regimented with your cheat day planning. To start, Werner recommends considering a diet break every 12 to 16 weeks, for anything between a day to two weeks.

If you're already sick of your diet and feeling fatigued before that marker, then you might be eating the wrong things, she said.

But beware of stretching past a fortnight on a diet break, Werner said, because it might be hard for you to get back to the healthy eating habits. 

'Allow yourself to eat a few foods you haven't in a while, and increase calories by a few hundred a day. It doesn't mean it's a free-for-all,' she said.  

If you plan your indulgences in this way, it could help you to feel less guilt when indulging, Werner said.