“If It Fits Your Macros” (IIFYM) is an increasingly popular, yet not exactly new dieting approach. It involves staying within a certain, pre-determined range of macronutrients; protein, carbohydrate and fat totals, but still being allowed the flexibility to have “non-diet foods” on occasion as long as those foods do not push you beyond any of those individual macronutrient ranges. In IIFYM dieting, the term “clean food” is almost laughed at. So if you want to have some ice cream or a donut or some cookies or pizza or whatever, it’s perfectly ok, just as long as it still- “fits your macros”!
One of the pro’s of this type of dieting is that having variety for many people can make compliance a lot easier. It also leaves room for some fun favorites and can reduce the pressure that some people feel during a diet. The cons are less obvious but no less serious. For some people, certain foods like sugar can act as a trigger to have even more. Also, not all foods are created equal in terms of how they effect your body and endocrine system, and how you will respond to them. Just as all calories are not the same in terms of how they are used by the body, all macronutrients types are also not quite the same. Grams, which macronutrients are measured in, are simply units of weight and not directly cross related to how each one will effect the body. For example 40 grams of high sugar, fast digesting carbs can give you a different endocrine response than 40 grams of low sugar, slow digesting carbs.
Finally, while it may not be that difficult to fit in the occasional off-the-norm item, if the dieter starts trying to manipulate their food choices to include more of their fun favorites, they may be subbing out better quality, healthier foods and overcomplicating their diet in terms of possible options or what may actually be more ideal for them.
As a nutritional consultant, I’ve always advocated having a variety of choices and think this approach can be good if used responsibly. IIFYM may be an “easier” diet system to follow long-term for many which can be key to their success. But if taken to the extreme and used as an excuse to have lower quality foods beyond what is best for you, then that could effect progress. Just because something may fit your macros doesn’t mean it’s the best thing for you to have or will lead to the best possible results.