What is the IIFYM Diet?

How to lose weight or build muscle by tracking your macronutrient intake

From "clean eating" to intermittent fasting and juice cleansing to eating clay, recent diet fads offer plenty of options to choose from for those looking to lose weight or simply implement healthier eating habits into their daily routines. One trend that has recently garnered increased attention, especially within the online fitness community, is called the IIFYM Diet.

IIFYM stands for “If It Fits Your Macros,” which means eating according to your body’s daily macronutrient needs. It’s sometimes referred to as “flexible dieting” because instead of following the recently popular trend of focusing only on whole foods, IIFYM allows the consumption of all types of foods (even foods that are widely considered as "junk") so long as they help you reach your daily macronutrient requirements.

Macronutrients are made up for three components: carbohydrates, protein and fat. The IIFYM Diet requires that you consume a certain amount of each based on your daily caloric expenditure and your goals (whether you’re aiming to build muscle or lose fat). For dieters with fat loss goals, IIFYM recommends a 15 to 20% reduction in daily caloric intake.

One of the biggest benefits of the IIFYM Diet is that it is entirely customizable and emphasizes the fact that every individual has different nutritional needs based not only on their goals, but also daily energy expenditures and genetics. At first, the diet may require a series of trial and error because it could take a few weeks of experimenting before you find the macronutrient ratio that work best for you and your body.

The idea behind IIFYM goes against the very popular trend of “clean eating,” which encourages the consumption of only natural, whole foods, not only to promote weight loss but also improve overall health and wellness.

One of the downsides to the IIFYM Diet is that it doesn’t place a high emphasis on healthful foods. However, the idea is not necessarily to frequently indulge in foods like French fries, ice cream and candy (which would typically be considered totally off limits while following a strict weight loss diet) but more so to provide flexibility that allows the inclusion of those types of foods every now and then without overindulging. This makes IIFYM a great option for those who have a hard time with very strict diets that label all “bad” foods as completely off limits.

“If two items are equivalent nutrition wise what makes one better than the other? Food shouldn't be viewed as clean and unclean but instead viewed as what's metabolically more beneficial for your body,” says Chelsea Schuur, a NPC Bikini Competitor and fitness blogger.

“IIFYM has helped me lead a way of life where I can have my cake and eat it too. I don't eat nothing but junk food all day long as most people assume, but if I want to go out to eat with friends despite being on a cut for a show I can.”

The first step in implementing the IIFYM Diet requires calculating a few factors that will help you determine your daily caloric requirements.

First you’ll need to calculate your Basal Metabolic Rate (BMR). This number is based on your height, weight and age and will determine how many calories your body expends while at rest. In other words, the amount of calories you would need to consume on a daily basis to keep your body functioning if you did nothing but sit still for an entire day.

Next, you’ll need to use the Harris Benedict Equation to determine your Total Daily Energy Expenditure (TDEE). This formula applies an activity factor to your BMR to determine an estimate of how many calories your body needs based on your daily activity levels.

For those with weight loss goals the IIFYM Diet suggests subtracting about 15% from your TDEE to determine your daily caloric intake. If you’re aiming to gain muscle it’s advised that you add anywhere from 5 to 10% to your your TDEE. From there, you’ll split that number up between carbs, protein, and fat to determine your daily macronutrient allotments.

Textbook macronutrient ratios recommend consuming about 25% of calories from fat, 50% from carbs, and 25% from protein. However, there are several different methods you can use to determine your macronutrient ratios and as mentioned before it will most likely take a few series of trial and error before you find a breakdown that works best for you.

“You can't follow strict diets forever without feeling cravings,” says Schuur. “IIFYM is much more of a lifestyle change because it teaches you about balance in life.”

You can play around and experiment with your personalized macronutrient ratios using the IIFYM Calculator on iifym.com, which will also provide a daily recommended amount of fiber to best help you meet your goals.

Once you determine your appropriate daily intake you can use a calorie counting app like My Fitness Pal to easily plan out or track your daily intake.