NutritionWeight Loss

IIFYM Diet Explained – A Guide for Beginners

If you’ve spend any time exploring diet options, you will have heard of the IIFYM diet, or ‘if it fits your macros’.

The overall premise of this diet is finding the right calorie intake and balance of your macronutrients (carbohydrates, protein and fats) to suit your goals.

Whether your aim is to lose weight or gain muscle, the IIFYM diet can maximize results and adapt to to your specific needs.

On top of that, it gives you a whole lot more freedom than a lot of diets. You can eat pretty much anything you like, as long as it fits within your macro and calorie restrictions. Sweet right?

Read on for:

  • What is the IIFYM diet?
  • How to calculate your macros
  • How to hit your macros
  • IIFYM foods

What is the IIFYM diet?

Woman looking confused about what to eat iifym diet

Pioneered by Andy Collova, he was bored and frustrated by traditionally restrictive dieting and decided to take a more flexible approach.

So when you see those super gorgeous insta influencers, sporting abs and tucking in to a huge slice of cake, they’re most likely on the IIFYM diet.  

The IIFYM diet is based around managing and balancing your three main macros, carbohydrates, protein and fat.

These are the three macros your body processes and turns into energy. By doing this, you can improve your fat to muscle composition and accelerate you towards your fitness or body goals.

To start the IIFYM diet you first need to calculate your macronutrients. Once that’s done, you need to stick to them and watch the results come rolling in.

Just remember, no foods are off the table with the IIFYM diet. So you can eat pretty much anything, but it has to fit in with your macros, or you won’t feel the benefit.

Want to complement your diet with exercise? Check out our weight loss workouts for women. 

How to calculate your macros

This is the first step of starting the IIFYM, and it involves a tiny bit of maths. But once you have the numbers down, you’re on your way to one of the most flexible diets you can find.

This is what you need to do to calculate your macros:

  • Work out your basal metabolic rate (BMR). This is the amount of energy you expend just by existing. Imagine if you just laid in bed all day and did literally nothing, that’s what you BMR represents. It’s based on your height, weight and sex.
  • Change to suit activity levels. You then need to multiply your BMR by your activity level. This provides your total daily energy expenditure, or TDEE. Essentially, it’s how many calories you burn in a day.
  • Adjust again based on your goals. If you want to lose weight or gain, you need to adjust your TDEE to suit your goals. For example if you plan to drop a few pounds, reduce your overall TDEE by 15-20% to lose weight safely [1].
  • Figure out your macros. First find your protein and fats using this method: Protein (4 cals per gram) should be around 0.7-1g per pound of bodyweight. Fat (9 cals per gram) is 0.25-0.5g per pound of body weight. Carbs (4 cals per gram) make up the remaining percentage of calories you have left.
  • gymgirl tip: ISSN have shown that, if you want to build muscle, you should consume between 1.4-2.0g of protein per pound of bodyweight [2].

How to hit your macros

The best way to meet your macros on the IIFYM diet is to use a food tracker. Apps like MyFitnessPal allow you to input your foods, and keep track of the macronutrients within them.

With these apps, it’s very easy to stay on top of your diet, whilst allowing you a lot more flexibility with what you eat.

However, although the IIFYM diet does allow a whole lot more freedom than most weight loss diets, it’s always a good idea to eat cleanly wherever you can.

For example if you have a burger for lunch, that can be up to 800 calories spent straight away. If you’re limited to 1600 a day, that’s only 800 calories for the rest of the day. As you can imagine, that’ll leave you pretty hungry later on that day. And you might fail to hit your macros too.

Absolutely treat yourself, however, just try to keep the majority of what you eat as clean as possible. Follow these simple tips and it’ll make your IIFYM diet way healthier:

1. For example, opt for lean meats which are high in protein and low in fats and calories.

2. Aim to consume complex carbohydrates over simple. These take longer to break down in your body, giving you a clean, slower lift of energy. They’re perfect for a workout.

3. Avoid simple carbs like sugar as they are pretty much empty calories. They’ll give you a short energy spike, use up a lot of cals and give you a crash after.

4. Eat nutritious foods. As fruit and veg won’t impact your macros that much, many people forget to eat them. You need the minerals and vitamins within to stay healthy.

5. Be honest. If you think you’re going to go over on your calories one day, it’s fine girl, you’re only human. Just make sure you’re back on it the next day.

[Related Article: 4 Gauge Pre-Workout Review]

IIFYM foods

Selection of healthy foods

Need a little inspiration to start meeting your macros? Check out these foods to get you started.

High protein foods

  • Chicken
  • Turkey
  • Lean beef mince
  • Pork
  • Eggs
  • Quinoa
  • Legumes – Beans, lentils, nuts
  • Tofu
  • Tempeh
  • Seafood

High fat foods

  • High fat meats – pork, beef
  • Avocado
  • Beans
  • Oils – Olive, coconut, seeds
  • Nuts and nut butters
  • Egg yolk
  • Chia seeds

Complex carb foods

  • Whole wheat bread
  • Whole wheat pasta
  • Oats and grains
  • Potatoes

The final taste – gymgirl hints and tips

Try out the IIFYM diet and see if it can help you achieve your body goals.

It’s super flexible and proven to work for so many across the world, so try it out and see if this is the diet to suit you.

Just remember to try and eat clean rather than go for the treats all the time. It’s a much better way to nourish your body and stick to your diet restrictions.


gymgirlfit was created by health and fitness enthusiasts, with backgrounds in powerlifting and writing. We've written for a number of well-known fitness publishing companies.

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