Flexible dieting, or If It Fits Your Macros (IIFYM), is the ‘dieting’ concept that, as long as you are hitting your calorie/protein/fat/carbohydrate numbers, working in a handful of chips or a couple Thin Mints isn’t going to affect your success… in fact, it will help you be more successful.

A lot of people have a very deep, visceral hate for IIFYM. I suspect this stems from two things:

  1. We believe a healthy diet requires giving up all ‘unhealthy’ food.
  2. Being unhealthy, overweight, or struggling to stick to a restrictive diet makes us lazy/stupid/bad.

This cupcake is going to go straight to my thighs…

Let’s tackle number one first. This one is really difficult because for a lot of us, this completely flies in the face of what we have been conditioned to believe and our world view. Calories and nutrients are what they are. Your body does not care if that protein came from a previously frozen chicken nugget or cage-free, grass-fed, organic chicken breast. The protein and how your body will use it is the same.

Now, this isn’t to say that you can avoid all nutrient-dense foods and still be healthy. Some foods are “better” from a nutritional perspective. Fat from peanut butter is going to be better for your blood lipid profile than fat from butter and fruit is a more nutrient dense carb source than white bread. If you have ever measured out your food, you have also probably noticed that 25 grams of carbs from yams takes up more volume than 25 grams of carbs from candy.

I was having lunch with a friend one day and she said to me ‘I think IIFYM is just an excuse for people to eat junk food.’ I shrugged and stuck my orange-stained fingers back into my bag of Cheetos. I had a craving for Cheetos, so I worked it into my macros. Because of this choice, I had significantly less fat to eat for the rest of the day, but I still had protein, carbs, and fiber numbers to hit. No problem, chicken breast and sweet potatoes for dinner.

IIFYM is absolutely not suggesting that you can live off of chicken nuggets; that would never fit your macros. It would extremely difficult to eat nothing but ‘junk food’ and hit your macros; I doubt it’s even possible if you consider your fiber intake as well (which you should!). If you are truly following your macros, you will still get the nutrition your body needs.

There are some good strategies for working in some tasty treats, so that you can enjoy a piece of cake on your birthday, or a glass of wine every night.

  1. Eat veggies
    Trading out some macros for a treat (like I did with the Cheetos) most likely means you are going to eat a smaller volume of food than you would have had with a more nutrient dense option. To help keep yourself feeling full and avoid further, unplanned indulgence, eat some veggies or sugar-free jello.
  2. Plan ahead
    If you know in advance that you will be attending a bake sale, plan your meals for the day around the cupcake, so that you still hit your macros. Meal prepping for the week or a couple days in advance is a great way to stick to your diet. It takes away the choice of which fast-food place you’re going to hit after a long day at work.

This brings us to the number two reason I think people have an issue with flexible dieting and actually a reason everyone struggles with maintaining a healthy diet. Most people believe that being overweight is a product of laziness and that giving in to a food craving (as I did with the Cheetos) is because of weakness and lack of willpower. Well, guess what? Science says we have limited willpower, and the more our willpower is tested, the less likely we are to resist.

Cookie or Radish?

A very interesting 1996 study* tested the depletion of willpower. Participants were left alone in a room that smelled of fresh baked cookies and assigned to either eat a couple of chocolate chip cookies from the table or a couple radishes.

The researchers then sneakily asked participants to help with another study aimed at determining problem-solving ability. They were given an impossible to solve geometric tracing puzzle. The participants were then told they could try as many times as they wanted to solve the puzzle. Here is the really interesting part, the group who were assigned to eat the radishes gave up on the puzzle faster than those who were assigned to eat the cookies, they also gave up faster than the control group that was brought in just for the puzzle portion of the study.

Generally, as a culture, we believe that certain foods are bad and we are bad or lazy if we allow ourselves to indulge in them. This is total crap. As was illustrated in the study above, willpower is a limited resource and it’s not just centered around food. Resisting a cookie when you are really, really craving one could impact other aspects of your life that require willpower.

So what does all this have to do with IIFYM? Well, if you actually work your cravings into your macros on occasion, you are far more likely to be successful long-term. Withholding treats that you enjoy because you think it’s a weakness basically guarantees that you’ll be standing in front of the pantry in the middle of the night wrist deep in your kid’s chocolate breakfast cereal. If you use the strategies above you will be on your way to successful fat loss while still being able to enjoy the foods you love, in moderation.  

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