The 90:10 Diet Rule and the Difference Between an A+ and a B+ Diet

How to Enjoy Your Favorite Foods in Moderation, Have a Normal Social Life, and Still Get the Nutrition You Need for Your Health and Fitness Goals


“I believe it’s healthier to be happy on a B+ diet than stressed out on an A+ diet.” – Matt Fitzgerald, Nutritionist and Endurance Coach

How is it that some people can just eat and eat and eat whatever they want and still stay healthy, lean, and fit? And how is it that many of the world’s longest living people are able to enjoy food and drink that isn’t healthy?

Well, it’s for a lot of reasons, one of which is that they tend to maintain balance in both their diet, and in their life, in general.

But how do you find dietary balance – and still have a life – in a culture that is so skewed in the wrong direction nutritionally? Good news! It can be really simple, and this post will explain how to do it.

Now, I couldn’t agree more with Mr. Fitzgerald’s assertion that it’s better to be healthy and happy on a B+ diet than stressed out on an A+ diet. To take it a step further, I also believe that achieving dietary balance is one of the cornerstones of excellent health and fitness, and that this requires an unorthodox approach in our very food-imbalanced culture. In other words, it doesn’t happen by accident. You have to be very intentional about forming a few key habits to make it happen. The 90:10 Diet Rule is one of those critical habits, and I’m going to teach three ways to make it work for you.

In my opinion, dietary perfection should be reserved for the realm of elite athletes – not your everyday fitness enthusiast. And even then, I’d imagine that there’s still some value in not eating perfectly healthy food 100% of the time. And by the way, when I say “elite,” I’m talking about actual professional and/or Olympic athletes whose career depends on their athletic performance, and for whom a near-perfect diet is necessary to achieve their performance goals.

Then again, Michael Phelps ate over 12,000 calories a day, and I’m pretty sure that about half of that was the mayonnaise on his fried egg sandwiches. And he’s the most decorated Olympian of all time with 28 medals (23 are gold medals). But I digress.

So, what’s the difference between an A+ and a B+ diet?

About 10%, roughly speaking.

In other words, an A+ diet is one where you’re eating healthy, nutritious, goal-supporting food almost 100% of the time. If that’s you, then you are a clean eating machine!

On the flip side, a B+ diet would involve eating healthy, nutritious, goal-supporting foods roughly 90% of the time. The other 10% of your food could be unhealthy, nutrient-void, goal-preventing junk. Like pizza, potato chips, or ice cream. So, a B+ diet allows some room for life’s less-than-healthy dining pleasures.

My colleague, Tom Venuto, who is a best-selling author on the topic of dieting, nutrition, and weight loss, has often recommended a 95:5 ratio between “clean foods” and “cheat foods.” I’ve also seen different references in the Paleo community that recommend an 80:20 ratio. I guess I’m in the middle with my 90:10 recommendation. But I don’t think of it as a strict rule. Some people may need to lean more towards the 95% “clean” spectrum. And for others, it may be no problem to hang out in the 80% range. It just depends on who you are, what your goals are, and how important they are to you, among other things.

The key is that you find the right balance for YOU, your goals, and your lifestyle.

So, how do we put this rule into practice?

It’s really quite simple: you have to figure out what works best for you because there is no one-size-fits-all, perfect diet that will work for everyone….which is exactly what you don’t want to hear. But it’s true.

We all have individual needs, goals, and food preferences. We all have specific tastes, temptations, and food sensitivities. We all have unique financial situations, daily schedules, social lives, and sometimes, other people to feed. Some of us have food addictions. And there are many other factors that go into personalizing a diet.

So, I’m not going to give you a meal plan and a shopping list. I’m going to teach you how to create those yourself using the 90:10 rule.

The 90:10 Diet Rule

Eat healthy, nutritious, goal-supporting foods about 90% of the time, and eat whatever you want the other 10% of the time.

This rule is based on the premise that if you’re eating good, healthy foods at least 90% of the time, then having some unhealthy foods isn’t going to rock the boat or drastically affect your diet or your fitness results. It’s also based on the premise that allowing some flexibility in your diet makes life a lot easier (and thus, healthier, less stressful, etc.).

Now, there are a few ways you can implement the 90:10 Diet Rule. You can break it down by calories, meals, or servings:

Method 1: Tracking Calories

Tracking your calories would be the most precise method for implementing the 90:10 diet rule. It’s also the most tedious because you have to measure your food portions and journal everything you eat. So, in my opinion, this method should be reserved for those who need accurate tracking (e.g. someone who has regularly struggled with their diet or weight loss) and are willing to learn how to do it.

Here’s how it works: if you eat 2500 calories per day, 250 of those calories could be a special, not-so-healthy treat. Or, if you eat 14,000 calories over the course of a week (i.e. 2,000/day), then you could have 1-2 cheat meals that total 1,400 calories.

Tracking your calories is a lot of work, but assuming that you’re reporting your calorie intake accurately*, it’ll give you the most precise feedback about what and how much you’re eating. This strategy is helpful, and even critical, for some people. And for others, it’ll drive you mad. If you want to use this method (or need to), I strongly recommend the book, Burn the Fat, Feed the Muscle by Tom Venuto which will greatly simplify the process.

Suggestion: don’t micromanage this 90:10 diet rule unless you need to. Those who may need to include:

  • people who are struggling to achieve their health, fitness, or body composition goals (e.g. weight loss)
  • people who have been unhappy with their body composition for a long time
  • people who have a medical condition that requires dietary excellence

If that’s you, then you may want to consider the calorie tracking method. And if not, I’d probably steer you in another direction.

*Studies have shown that most people don’t report their calorie intake accurately. Burn the Fat, Feed the Muscle can help fix that.

Method 2: Tracking Meals

This is the simplest way to track your food intake, but it’s also the least accurate and the most volatile method. So, if you eat three meals per day, on average, then you can have a “cheat meal” every 3-4 days (i.e. 1 cheat meal out of every 10 total meals). So, let’s say that you eat “clean” from Tuesday through Thursday. After that, you could go ahead and have that pizza you’ve been craving on Friday night.

If you eat three meals a day, on average, that works out to roughly two “cheat meals” per week. Or, if you have five small meals and/or snacks per day, then you can have a small treat every couple of days and stay within the 10% range.

The trouble with this method is that it can easily get the best of you. Plus, eating an entire meal that is unhealthy will usually have a noticeable, negative effect on your health and performance afterward. Not to mention that it’s really easy to overeat junk food, which is why I tend to recommend against this method. I’ve never been a fan of the idea of “cheat meals” anyway. But it works for some people. Like this guy…


Method 3: Tracking Servings (My Preference)

Instead of tracking calories or meals, I usually recommend tracking servings, which is still quite simple and seems to work well for most people. It’s the middle road that provides some of the best of both worlds. So, for every ten servings of food that you eat, one of those servings can be a less-than-healthy choice (e.g. a small dessert, some popcorn with your movie, or an occasional alcoholic beverage). Just make sure that your serving doesn’t turn into a full blown cheat meal.

This method takes some discipline. And if you aren’t actively tracking your servings, it takes some intuition, too.

The Key: Regardless of which approach you take, the key is looking backward and adjusting your approach based on both your performance and the results you’re getting. So, if you think back over the past week, and realize that you’ve eaten a lot more treats than you should have (maybe 70% clean, 30% junk), then you know you need to make some changes.

How I do it in “Real Life”

Personally, I combine the second and third strategy. I have an occasional treat (a serving) of “junk food.” For me, it’s often potato chips, ice cream, or a premium root beer. And every once in awhile, I’ll eat what some would call a “cheat meal” – like having pizza or Mexican food for dinner.

Now, before I have a treat, I usually do a little mental check-in and ask myself questions such as:

  • Do I really want this right now? Or, am I just bored giving in to a craving, or some other silly reason?
  • How has my diet been this week? And when is the last time I had a special treat?
  • Does the occasion merit an indulgence?

Now, this isn’t some long and drawn out process that I stress about. It’s just a moment I take to be intentional about what I’m eating. I’ve also found that it’s much simpler if I save special treats for special occasions (e.g. social events and meaningful celebrations). I’ve got enough of those in my life where it seems to work well.

Our family also follows food author, Michael Pollan’s advice to “make it yourself” if you want a treat. So, we usually don’t go out and buy a tub of ice cream. Instead, we’ll make a batch of homemade ice cream at home every once in awhile. This takes more time, planning, and work, but everyone knows that homemade is best. Making treats from scratch isn’t convenient, and that’s the point. I’ve also found that when it’s homemade, I don’t need to eat as much to satisfy a craving.

We also experiment with making healthier versions of our favorite comfort foods. For example, we’ve got a great, healthy pancake recipe made of whole foods that the kids (and Dad) gobble up.

Finally, we’re really intentional about trying to enjoy everything we eat, including the 90% foods (i.e. the healthy stuff). And so, we prepare all of our foods the way we like them. This way, we don’t feel like we’re depriving ourselves of “the good stuff.”

So, these are some of the things you can do to create balance in your diet, and enjoy an occasional treat in moderation.

The Bottom Line

In terms of your health, fitness, and performance, the difference between eating well 90% of the time and 100% of the time is marginal. However, in terms of your happiness, stress levels, and your social life, among other things, the difference is significant. Life is a lot easier and more enjoyable when you don’t expect dietary perfection 24/7. I might even argue that eating well 90% of the time is healthier overall, for that reason alone.

So, if you find that you’re eating too much junk food, and want to take control over your diet to gain some balance, put the 90:10 Diet Rule into practice using whichever strategy makes the most sense for you.

In summary, eat this stuff most of the time…and the rest of the time, eat whatever you want.

healthy foods

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One Response

  1. Great ideas! I’ve done something like this for a while but my “cheating” tends to come in cycles. I’ll be motivated and eat really well for weeks and then I’ll start eating bad foods more and more. It typically doesn’t get out of hand though. When I start to see changes in the mirror or notice my pants fitting tighter, I go back to my clean eating ways. My overall weight might fluctuate 5-10 pounds during these cycles which isn’t a big deal at my current weight. Another thing that made my life noticeably stress free-er (that’s a word right?) is my bathroom scale broke and I only made diet changes based on how I felt and how I looked in the mirror.

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