CrossFit Nutrition: What you need to know

nutrition guide for crossfit

With so many elements to consider when putting together your nutrition plan to support your CrossFit workouts, it can be very difficult to know where to start and what to prioritize.

In order of most impactful on your body composition to least impactful, here are the 5 elements to take into consideration:

We’ll take a look at each one of these and how you can adjust them to maximize your CrossFit performance and get the results you’re looking for.


Understanding the amount of calories that you need to fuel your workouts is the single biggest factor which will help you to improve your CrossFit performance.

Many people don’t know how much they should be eating, and often eat too little, which eventually takes its toll on your performance.

If you undereat, you’re fuelling first your workouts and then your bodily functions, which means that whilst your workouts may feel like they’re going well for a while, other parts of your body will suffer.

For example, you may feel like you struggle to concentrate or think properly, or if you’re a woman then your period could become irregular or you could lose it completely.

Over time, your body struggles too much from the lack of calories to even be able to fuel your workouts correctly. So it’s time to fix that!

Calculate your calorie needs

To calculate how many calories you need to maintain your current weight, you can estimate it by multiplying your weight in pounds by 15.

This is roughly what you would need on a day where you have a moderate training session (1-2 hours long, 10-25 working sets).

For rest days, take 300 calories off this amount and for double training days where both workouts are moderate or one is hard, add 300 calories.

So for example, a female weighing 140 pounds would need:


Rest day: 1800 calories
Moderate day: 2100 calories
Hard day: 2400 calories

This would be to maintain calories.

To lose weight, you need to take 500 calories from each day, so for our female that would be:


Rest day: 1300 calories
Moderate day: 1600 calories
Hard day: 1900 calories

And to gain weight, for example in order to build muscle, you need to add 500 calories to each day:


Rest day: 2300 calories
Moderate day: 2600 calories
Hard day: 3000 calories

Remember that all calorie calculations are estimates, and they may need adjusting to find the right amount for you.

To measure if you’re getting the right amount, weigh yourself every week for 3 weeks.

In maintenance mode, you should not lose or gain more than 1.25% of your body weight. If you do, then you need to reduce or increase your calorie intake accordingly.


Now that you know how many calories you should be eating each day, how do you know how to split them into carbohydrates, protein and fat?

Let’s start by looking at the most important macronutrient for CrossFit training: protein.


Without enough protein, your body is unable to repair and grow your muscles, and during your workouts your body will actually use your muscle tissue as fuel.

So protein is the most important macronutrient for building and maintaining muscle.

A recommended amount for CrossFit athletes and anyone who practices strength training, is 1g per pound of bodyweight.

So for our example client, that would be 140g per day. This doesn’t change by training day as protein is always needed in a high amount, not only to build the muscle but to maintain it.


Carbohydrates power your cells, in particular they power the contraction of your muscle cells, which is vital when you are performing any kind of exercise, especially CrossFit and strength training.

There are no notable downsides to having a very high carb intake as long as you consume adequate amounts of protein and fat.

However, we recommend changing your carbohydrates according to your training days.

On days where you are not training, you will need fewer carbohydrates and on training days you’ll need more.

Here are the recommendations:


Rest: 1g carbs per pound body weight
Moderate: 1.5g carbs per pound body weight
Hard: 2g carbs per pound body weight

For our female athlete this would be:


Rest: 140g
Moderate: 210g
Hard: 280g


Fats are essential to our health, as they regulate our hormones which control many processes in our bodies.

The minimum amount of fats per day for health is 0.3g per pound of body weight, which would be 42g for our example client.

After you have consumed the minimum amount, there are no added benefits to your training when consuming more fats, but they can help you to reach your target number of calories as they are easy to eat and contain more calories than protein and carbs.


There are 4 calories in 1 gram protein
There are 4 calories in 1 gram carbohydrates
There are 9 calories in 1 gram fat

To calculate the amount of fat you can have, first calculate how many calories are taken up with the protein and carbohydrate recommended amounts, and then divide the remaining calories by 9 to get your recommended grams of fat (which should be above the minimum).

So, for our example client, here are her goals to maintain weight:


Rest day: 1800 calories
Moderate day: 2100 calories
Hard day: 2400 calories


Rest day: 140g protein, 140g carbs, 76g fat
Moderate day: 140g protein, 210g carbs, 78g fat
Hard day: 140g protein, 280g carbs, 80g fat

As long as fat is at its minimum, it’s possible to eat less fat and more carbs if that’s easier for you to achieve your calorie intake.

Remember, calorie intake is most important and the macro split is second.

Nutrient timing

Knowing when to eat what is a common problem for a lot of active people.

Most of us know that we should eat before and after a workout, but how long before or after and what should we be eating? Does it really make a difference?

Well, if you’re already consistently hitting your calories and macros, nutrient timing can make a difference to your performance.

Otherwise, it has a much smaller effect because your primary needs (enough calories and macros) are not being met.


Working out on an empty stomach is definitely not going to result in optimal performance, so make sure that you fuel yourself correctly.

Ideally, you should eat a medium sized meal 3-4 hours before a workout and a small amount of protein and fast-digesting carbs 30 minutes before.

If you work out in the mornings, you will have to skip the meal but make sure you fuel 30 minutes before.

A few example snacks could include:


Plain greek yoghurt with honey
Oatmeal with berries
Apple with almond butter and raisins
Carbohydrate supplement shake


If your workout lasts for more than 1 hour, it might be helpful to you to consume carbs and protein during your workout.

Consume fast-digesting carbs with small amounts of fast-digesting protein (such as whey).

It should contain no more than 5-10% of your daily protein and slightly less than your max carbs per hour (0.3g/lb body weight).


After any type of workout, it’s important to have a snack or meal to start off the recovery process.

Recently trained muscles are extra sensitive to carbohydrates, so it’s the ideal time to consume carbs to refuel your muscles as this sensitivity gradually decreases over the following 3-6 hours.

Protein should be consumed with the carbohydrates as well to ensure that muscle repair begins.

Fats should be kept to a minimum because they slow down the process of digesting carbohydrates.

Before bed

Eating the right type of food before bed can help your recovery from one day to the next.

However, eating too close to bedtime or eating the wrong type of food can cause gastrointestinal distress and disrupt your sleep.

Consuming fat slows down the digestion of protein, which is beneficial overnight however, it can cause you to have a disrupted sleep, so try to be aware of this and monitor how things go for you.

My advice for a bedtime snack is casein protein with low fat or alternative milk, as this is slow-digesting protein – perfect for before bed.

Food composition

Food composition refers to the quality of the food that you are eating.

Let’s imagine that you can choose between an apple and a candy bar for your snack.

Candy bar vs apple

A candy bar may help you to get your calories higher for the day, but those calories will be from processed sugar and unhealthy fats.

The apple, however, will contain a lot less fat and it will also provide you with vitamins and minerals that are essential for muscle growth and general health.

Let’s have a look at how you can choose high quality foods for each of the macros.


A good quality protein is one that is well-digested by the body, is complete (meaning it contains all of the essential amino acids our body needs) and also contains some vitamins, minerals and fiber.


High quality sources of protein include:
Eggs and egg whites
Lean cuts of meat
Plain greek yoghurt
Beans and lentils (for plant-based diets)

This doesn’t mean that every time you eat protein it has to be one from this list, but try to include at least one of these in your diet every day.


A good quality carb is one that is digested slowly by the body (although there are times where fast-digesting carbs are preferable) and one that is nutrient dense.

High quality sources of carbohydrates include:


Beans and lentils
Fresh and frozen fruit
Sweet potato
Whole grain bread
Whole grain pasta
Plain yogurt

It is a good idea to compose your diet of mainly this type of carbohydrate, except around your workouts, where you will need fast digesting carbs.

Examples of these are:


Protein powders
White rice


Fat quality is determined by its type. There are four main types.

Monounsaturated fat

This type of fat promotes good health when eaten in the right quantities and is found in plant sources, such as olive oil or avocados.

Polyunsaturated fat

This type of fat can be found in vegetable oils, some nuts, fatty fish and grass-fed animal meat.

You may have heard of Omega-3 and Omega-6 fats, which are found in fatty fish.

These are essential to our health and it is common for people to under-eat Omega 3.

Saturated fat

This type of fat comes mainly from animals, such as meat, eggs and dairy.

Whilst it is not recommended to eat a large quantity of this type of fat, it can certainly be beneficial to have it in small amounts.

Trans fat

Trans fat is very rarely found in nature, and is created artificially to give products a longer shelf life.

Studies show that consuming a high quantity of trans fats is not healthy and has negative effects on the body.

In general, try to eat monounsaturated or polyunsaturated fats where possible, and include a low level of saturated fats. Avoid trans fats as much as possible.

Here are some examples of foods containing healthy fats:


Extra virgin olive oil
Egg yolks
Peanuts (and natural peanut butter)
Seeds such as chia and flax seeds

Having a diet with a variety of healthy foods as described above can keep you feeling healthy and energetic and improve your CrossFit performance.


Supplements are the last thing that should be added to your diet, after you’ve made sure you’re eating enough calories, enough of each macronutrient, and you’re also eating at the right times and choosing good quality foods. Only then will taking supplements make enough of a difference to your CrossFit performance.

Whilst there are tonnes of supplements out there, research has shown that not many of them are actually proven to work in the way they advertise. It is also important to note that in many countries, including the US, it is legal to make unfounded claims about a supplement.

Studies show, however, that the following supplements are proven to help with performance when used correctly:


Whey protein
Casein protein
Carbohydrate formulas
Multivitamins and minerals


If you want to improve your nutrition to support your CrossFit workouts, make sure that you consider each of the five categories in order of most impactful (calories) to least impactful (supplements).

Focus on getting good quality food in the right quantities at the right time of day and you will see a great improvement in your general health and CrossFit performance if you consistently do this.