It’s a classic dieter’s tale: Amped up about our health goals, we dive in 100 percent to a new eating plan, believing that, with a whole lot of willpower and a little bit of luck, this will be the time it sticks. To prove we’re in it to win it, we clear the pantry of cookies, prep a week’s worth of salads, and swear we’ll never touch another margarita. Before long, however, reality sets in. Denying ourselves day after day becomes a major emotional strain, and pretty soon we’ve crashed and burned — another diet attempt foiled, another reason to beat ourselves up. When good intentions end up leading to failure, how do we break the cycle?

A woman takes a bite of a pink-glazed donut covered in sprinkles

A more moderate approach may be the answer. Many nutritionists recommend following the “80/20 rule,” which in this context allows for following a diet hard-core 80 percent of the time, with a 20 percent margin of error. Dietitians tout this as a more humane and reasonable methodology than striving for the often-unrealistic expectation of 100 percent devotion. “The 80/20 principle is designed to be a lifestyle, not a diet,” explains Stephanie Wagner, a registered dietitian nutritionist who follows the principle herself and encourages it for her clients.

Building in a 20 percent cushion can alleviate the feelings of chronic deprivation many people struggle with when dieting. “We often want what we can’t have,” agrees Wagner. “The greater we resist temptation and the more we deprive, the harder it becomes to fight off those urges.” Knowing an indulgence here or there won’t undo all your positive efforts loosens up harmful, perfectionistic attitudes toward food. It can help us find the balance of establishing healthy eating patterns — while embracing the concept that food also provides pleasure. Though downing cupcakes on an everyday basis isn’t advisable for your health, special occasions sometimes call for special “treat” foods. Isn’t it nice to be able to enjoy them as part of a well-deserved celebration?

Since much of the difficulty with following any diet to the letter comes from life’s unexpected circumstances, a little wiggle room can also offer some necessary flexibility. Social gatherings, busy schedules, or restaurant dining often make adherence to a specific eating plan a challenge. (When your future mother-in-law makes you her famous spaghetti, are you really going to refuse on the grounds that it’s not Paleo?) “Instead of avoiding food and social situations, the 80/20 principle allows some room to live your life,” Wagner notes. The 80/20 rule can also be a best practice for anyone just dipping a toe into nutritious eating after a long stretch of less-than-healthy habits. Massive changes executed cold turkey rarely last. Instead, easing into a diet to achieve 80 percent compliance may result in more sustainable health outcomes. “With more freedom comes more success,” Wagner encourages.

A woman sits in a cafe with a drink and a plate of macarons

Though the 80/20 principle offers many advantages, one-fifth “food time off” can be a slippery slope. (It’s definitely not intended as an excuse to stuff your face with reckless abandon.) So how do you make sure your 20 percent doesn’t undo all the good of your 80 percent? “While this approach prevents deprivation and bingeing, the lack of parameters makes it difficult to set boundaries when it comes to portions and calories,” admits Wagner. “The key to success comes down to portion and calorie control on both sides of the aisle. As with your nutritious meals, keep your treats reasonable. Portions still count. A small slice of cake, a glass of wine, or a piece of dark chocolate won’t derail your week.” To set yourself up for dieting success, you may want to establish specific boundaries. Choose weekends as your designated days for desserts, or give yourself permission to order restaurant meals without restrictions on date nights.

Wagner emphasizes that using up your 20 percent isn’t mandatory, either — especially if you’re getting in the groove of whatever healthy eating plan you’ve chosen. “Keep in mind you should always listen to your body’s signals. If you feel full or the cravings aren’t there, feel free to skip the treat.” And, of course, for diets of medical necessity (such as gluten-free eating for someone with celiac disease), time off unfortunately isn’t an option.

As for your remaining 80 percent, dive in to whatever healthy eating plan you’ve chosen! Wagner offers a commonsense nutrition approach: “Aim to fill half your plate with fruits and vegetables. Then, use the remainder of the plate to add in a lean protein source like chicken, pork, eggs, or nuts, and feel free to include a complex starch like sweet potatoes, brown rice, beans, or whole-wheat pasta.” Regardless of the diet, you can keep your motivation going strong knowing you have the freedom of a little wiggle room.

Have you tried the 80/20 approach to a diet? Tweet us at @BritandCo!

(Photos via Getty)