Is Flexible Dieting Right For You?

Published on July 25th 2017
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IIFYM or If It Fits Your Macros (also known as “Flexible Dieting” and “Macro Counting”) has been rapidly gaining popularity as one of the best diet plans around. IIFYM is another form of calorie counting where you are not only given a calorie goal but also a carbohydrate, fat, and protein goal. Aside from these “macro” parameters you are free to consume whatever foods you want. Bodybuilders, cross fitters, powerlifters, treadmill addicts, men, women, those seeking to lose fat and those seeking to gain muscle are betting on this non-restrictive diet plan that claims that there is no need to change your food choices in order to reach your goals.


As a Registered Dietitian and professional nutrition coach who has worked with different types of people with varied health and fitness goals, there are many components of this diet that appeal to me and just as many that do not.

So first, let’s talk about what makes this eating plan so great.

Food Labels and Portion Control

IIFYM forces you to look at the Nutrition Facts label and recognize what your food is made up of (in terms of calories, carbohydrate, protein, and fat) and appreciate the recommended portion sizes. Most dieters have an extremely poor understanding of how much food they are actually consuming in a day. With IIFYM you keep track of everything you eat in an app like MyFitnessPal or Loseit by either scanning the barcode on the package or by meticulously weighing/measuring your food and entering the item manually. This act of measuring and weighing your food eliminates the “mindless eating” factor which so many of us struggle with. It also creates an extremely eye-opening experience that can greatly impact your weight loss success. There are many foods, even some that are considered “health food” that have way smaller portion sizes or contain way more Calories than you would think. Just try weighing out one serving of peanut butter (32g) and you’ll know exactly what I’m talking about.

Does Not Restrict Food Groups

Move over low fat and low carb diets - there’s a new man in town. IIFYM promotes the not so novel approach of eating all three macronutrients in fairly reasonable amounts. We all know at this point in 2017 that there really isn’t a reason to eliminate food groups or certain macronutrients. In fact, we know that this practice of food group elimination is worse for our health and our waistlines. Eating from all food groups goes right along with the boring, unsexy, Dietitian endorsed mantra “everything in moderation”. But kudos to the genius that made it trendy!


Many of us are motivated by goals. Challenging yourself each day with hitting carbs,protein, and fat is invigorating, fun, and almost game-like. IIFYM gives you the opportunity to feel successful by not only hitting caloric goals but also hitting your macro goals.

You Will Lose Weight

The best perk of all! Yes, you will lose weight. Like with any diet where you are eating at a deficit you will surely see those numbers on the scale go down. And for those who struggle with self-regulation or detecting when they are hungry or full, this approach works particularly well. When your macros are gone, you stop eating. As simple as that. It won’t immediately and rapidly melt fat off your body, as claimed, but you will certainly lose poundage. And because of the emphasis on eating adequate amounts of carbs and protein you probably won’t even lose that much muscle. Score! Macro Counting is life!!

Or is it? Now let’s talk about where Macro Counting/IIFYM/ Flexible dieting comes to a screeching halt and breaks down.


While macro counting has many positive features, one area that it does not address is eating for health. With the standard American diet being filled with processed, chemical laden food can we really expect to continue eating these foods while on a deficit and stay well? Following the IIFYM diet, you are in no way guided to make your health a priority. It is just as easy (actually easier) to “hit your macros” with poor quality packaged foods. Just scan the label of processed protein bars, chips, Big Macs etc. Moreover, this eating plan does not address gut health, dysbiosis, hormonal regulation, medications or current medical conditions. All of these things and more can greatly impact your ability to lose weight.

IIFYM does not address balanced meals and how food works in your body. So if you eat all of your carbs and fat in the morning and afternoon, you are technically in the green if you eat your hundred-and-something grams of protein all at once for dinner. Protein, specifically, needs to be eaten throughout the day in order to be utilized to its full potential. Therefore, if your goal is muscle building and you are not aware of this fun fact you will be essentially wasting your “gainz” potential.

Can you follow IIFYM and eat “healthy” food? Absolutely! Eat lots of vegetables (which will fill you up and improve your energy), choose unprocessed protein and carb sources and healthy fats. Stay within your macro goals while adhering to healthy eating guidelines and voila you have the best of both worlds.

Yes, a treat is ok once in awhile or even several times per week. Most Registered Dietitians, myself included, encourage their clients to not restrict themselves from the foods they love but to work them into an overall healthy lifestyle (again with the “moderation” thing).

Having to Log all of Your Food Can Be Stressful and Socially Isolating

Let’s face it. Macro Counting is a HUGE hassle. Yes, you get used to it and it becomes less torturous to have to do math before you eat. But for those who are not extremely motivated, it is hardly a sustainable way to live. There is nothing worse than declining social events or asking the host/hostess to tell you every ingredient in their lasagna so you can track accurately. It’s just annoying. And yes, you can guestimate and get on with your life but the less precise you are with tracking the more it negatively impacts your goals. This is the breakdown with most popular diets on the market that involve strict weighing or measuring of your food without thought to why you are eating what you are eating. When you learn how to ask yourself: “Am I hungry?” “Why am I eating this?”, “How is this food going to make me feel?”, “How much do I need to eat in order to feel full?” then meticulous and socially frustrating tracking no longer matters so much.

It’s Most Likely Unnecessary

Adding to the previous topic, unless you have less than 20 pounds to lose it is probably extremely unnecessary for you to go through the ordeal of tracking everything you eat in order to be in a calorie deficit. Most people who have a substantial amount of weight to lose can identify one or two eating habits that they can change that will promote weight loss. For example, if you drink soda all day long you are consuming an additional 150 calories for every can. It takes a daily deficit of 500 Calories or a weekly deficit of 3500 Calories to lose 1 pound of body fat. So if you’re drinking only 3 cans of soda a day, removing this from your diet will cause you to lose 1lb per week of body fat. Add some exercise on top of that and you’re looking at a total of 1.5-2lb weight loss per week. And there you have it. I just gave you the secret to sustainable weight loss. Identify eating habits that are not ideal, slowly change them over time, and maybe even adding some exercise to the mix.

You Do have to Say No to Foods You Love

The allure of IIFYM is in not having to change your food choices in order to lose weight. It’s loudly touted on macro coaches’ home pages that you will “never have to say no to foods you love”. However, sometimes if you want to hit your macros you will eventually have to say no to that 300 Calorie doughnut that has a whopping 40 grams of carbohydrates or that 430 calorie Grande Frap that contains 72 grams of carbohydrates, and 14 grams of fat. You will have to take a pass on foods you want in order to meet your macro goals. I don’t know about you, but I call this not only false advertising but a total bummer. The truth is, there is no magical technique to weight loss. While weight loss can be complicated, especially for those with underlying health issues, the basic precepts remain the same: nourish your body, eat less, move more. Any diet that promises quick results or never having to make a compromise is lying.

Carbohydrate Craving and Hunger Regulation

Because of the lack of emphasis on nutritious food, Macro counting does nothing for those who struggle with sugar addiction or hunger regulation. I partially discussed this above but felt as if it deserved its own salute. Time for me to get all science-y. When you have “bad bacteria” overgrowth or dysbiosis in your gut from eating crap your whole life there is communication between your gut and your brain. The “bad bacteria” thrive on sugar. Therefore, the gut bugs will signal to your brain that it needs carbohydrates (candy, bread, pasta etc). This then translate to you as a hefty urge to eat a pop tart. Moreover, your gut health influences hormones that are responsible for hunger regulation, namely: ghrelin and leptin. Ghrelin is the hormone that signals hunger to your brain and leptin is the hormone that signals satiety. Ghrelin is produced not only when your stomach is empty but also in response to intestinal inflammation. The long and the short of it is when your gut does not have the correct balance of bugs your satiety hormones are decreased, your hunger hormones are increased while simultaneously you are having a wicked strong hankering for a banana split. Every time you give in to the pop tart or banana split (despite whether or not they may fit your macros) you are perpetuating this vicious cycle. As you can imagine, this is a recipe for frustration and failure.

Take Home Messages

Overall, there are many positive qualities of this eating plan. While eating a balance of all three macronutrients (carbs, fat, and protein) is really nothing earth shattering or new, IIFYM has just made it cool. If you have a relatively good understanding of nutrition and do not have that much weight to lose, then this diet can really work for you. However, if you are just breaking free from the conventional American way of eating and know very little about nutrition, this diet may not be the most effective or beneficial course of action. Like with any diet or health regimen, one size does not fit all. The best approach is to find a strategy that is the most sustainable for you that will support all of your health and fitness goals.