Macros and IIFYM, Explained (2017 UPDATE)

alafitness Hollywood personal trainer Los Angeles IIFYM macros diet meal plan

So, what are macros?

Macros, short for macronutrients, are the nutrients that provide calories from food. They consist of proteins, carbohydrates, and fats.

Protein helps build lean muscle and repair broken tissue -which is what happens to your muscles during a workout. Protein burns more calories gram for gram because it requires more energy than the other macros for your body to digest it. Thus, high protein diets aid in fat loss.  1 gram of protein = 4 calories

Carbohydrates (carbs) are stored in your muscles, organs, brain, and blood as glycogen which is used by our bodies as energy and fuel. Fiber is also a carbohydrate but doesn’t provide calories.  1 gram of carbohydrate = 4 calories

Fats are commonly misconstrued as bad nutrients, ie fats make you fat. False. Fats help protect your organs and are essential for hormone regulation, vitamin absorption, as well as brain function.  1 gram of fat = 9 calories

Also note, there are micro-nutrients that your body needs to function, but only in small amounts within your diet. That’s why they are not calculated and tracked. Vitamins and minerals are micro nutrients that help your organs grow.



If It Fits Your Macros (IIFYM), also known as flexible dieting, is a dietary lifestyle revolved around meeting daily macro intake targets, regardless of the food eaten to achieve them. Therefore, you plan how much of the above macros- protein, carbs, and fat, to consume based on your fitness goals of building muscle or losing fat. Essentially, IIFYM explains no matter the source of food – processed or “clean”, our bodies will metabolize them the same.

Does it work? Well, there are many perceptions and bias around whether this is effective. Let’s back up… in order to lose fat, you must consume fewer calories than you burn. The body will then use the energy from stored fat to function. Therefore, when strictly referring to weight loss, a calorie is a calorie regardless where its from.

However, when it comes to body composition, a calorie is not just a calorie. The quality of weight loss will not be optimized if macros are ignored. Inadequate intake of any of the three macros will not aid in achieving your desired aesthetics – low protein can lead to muscle loss, low fat can cause hormone imbalance, and low carbs impact training abilities. To achieve a healthy, athletic body you need to be count macros, which directly correlates to calories.

IIFYM works by calculating your daily caloric needs, then distributing those calories into 40% carbohydrates, 40% protein, and 20% fat. This ratio is promoted as the most effective for muscle growth, fat burning, and keeping energy levels up. However, based on your goals and how your body reacts to your macros, these ratios are commonly altered slightly.

How to Calculate Macros

1) First, you will have to determine you basal metabolic rate (BMR) which refers to how many calories your body burns at rest.

For women: 665 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) – ( 4.7 x age in years )

For men: 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)

For instance, a 32 year old, 5’4″ tall woman who weighs 135 pounds would need about 1403 calories.

665 + (4.35 x 135) + (4.7 x 64) – (4.7 x 32) = 1402.65

2). Once you’ve calculated your BMR, you will need to factor in how active you are.

BMR x 1.2 for low intensity/sedentary

BMR x 1.375 for light exercise, 30-45 mins 3-4 days/week

BMR x 1.55 for moderate exercise 3-5 days per week, 30-60 mins

BMR x 1.725 for active individuals exercising 6-7 days/week at moderate to high intensity

BMR x 1.9 for extremely active individuals engaged in heavy/intense work or exercise 6-7 days/week

The same 32 year old woman is moderately active, so she would need 2174 calories  (1403 x 1.55) to account for calories burned during exercise.

3). Portion out your calories to meet your macro ratios.

So, with 2174 calories,

Protein: 2174 (total calories) x 0.40 (40% protein) = 869.6 = 870

Carbs: 2174 (total calories) x 0.40 (40% carbs) = 869.6 = 870

Fats: = 2174 (total calories) x 0.20 (20% fats) = 434.8 = 435

As discussed above, 1 g of protein and 1 g of carbohydrate is equal to 9 calories, while 1 g of fat is equal to 9 calories. Therefore, divide the calories amounts by 4 and 7 respectively. This concludes in approximately 218 g protein, 218 g carbohydrates, and 62 g fat.


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  1. Hey Abby! Love this article! Just wanted to point out a couple of typos since they are pretty important for someone understanding iifym!
    The first time you mention calories in fats, it says there are 4 cal/gram, and at the end of the article it says that protein/carbs also have 9 cal/gram, as well as fats.

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