The 90% Rule is as simple and effective as it sounds.
In terms of nutrition and fat loss, as long as you have about 90% adherence to your diet, you’ll still see incredible results.
How do you determine what 90% is???
The easiest way to determine the percentage of adherence is to actually count your meals and whether they fall into the category of "your diet" or "cheat meal".
9/10 meals is 90%.
Let's give you an example: Say you have 3 meals a day. That means 3 full days of eating within your diet is 9 meals. Technically, your next meal can be a cheat meal and you won't lose your hard earned gains.
*** Now there is a caveat here... This "cheat meal" does not mean eat everything in front of you including a Big Mac Meal and an Oreo Mcflurry and then a bag of potato chips. No no, you still want the meal to be a general portion size. Do not forget that calories DO matter. ***
Advanced Method - Calculating Your Macros
A more advanced way to calculate your 90% is if you track your calories and macros. In this case, you know what your target caloric intake is for the week. If you're within 10% of your target caloric intake is for the entire week guess what, you're still likely going to see great results and lose fat.
This sh*t isn't that complicated, don't over-stress your diet. Take things one step at a time. Nothing in your diet needs to be totally restricted unless it's for medical reasons. Keep at it, have some fun, cheat up to 10% of the time (on your diet that is) and you're on your way to that vacation bod!