Workouts at CrossFit gyms are strenuous and fast-paced.

They change daily and involve gymnastics, weightlifting and cardiovascular exercises, such as running and rowing, among other activities.

To do your best, you have to be properly fueled. In fact, nutrition is viewed as the foundation of CrossFit training and critical to performance.

The CrossFit diet is moderately low in carbs and emphasizes consuming macronutrients from whole plant foods, lean proteins and healthy fats.

Here is a closer look at the CrossFit diet, including what to eat and what to avoid.

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As a general guide, the CrossFit website recommends that athletes “eat meat and vegetables, nuts and seeds, some fruit, little starch and no sugar” and “keep intake to levels that will support exercise but not body fat.”

More specific CrossFit dietary recommendations are based on the Zone Diet, which was developed over 30 years ago by Barry Sears, a biochemist and author of The Zone.

The diet is designed to control blood sugar and minimize inflammation, which may curb hunger and reduce your risk of chronic diseases, such as obesity, heart disease and type 2 diabetes. Reducing inflammation may also bolster recovery from workouts (1, 2, 3, 4).

To plan a balanced, Zone- and CrossFit-friendly meal, divide your plate into thirds and fill it with:

  • 1/3 lean protein: Options include skinless chicken breast, fish, lean beef and low-fat dairy.
  • 2/3 healthy carbs: Emphasize colorful, non-starchy vegetables and fruits with a low glycemic index (GI).
  • A small amount of healthy monounsaturated fat: Olive oil, avocados and nuts are a few options.

The CrossFit website recommends you try the Zone Diet for four weeks, then tweak it based on your needs.

Notably, not all CrossFit trainers provide the same diet advice. Some recommend the paleo diet, which entirely omits dairy products, grains and legumes (5).

It’s also possible to combine the two — eating a paleo-style Zone Diet. Additionally, you can modify your diet to fit a vegetarian or vegan lifestyle.

Summary The CrossFit website recommends the Zone Diet, which is designed to stabilize blood sugar and minimize inflammation. A typical meal is made of 2/3 healthy carbs, 1/3 lean protein and a small amount of monounsaturated fat.

The CrossFit-compatible Zone Diet advises consuming 40% of your calories from carbs, 30% from protein and 30% from fat — but says that elite athletes may need more fat.

To simplify the diet and ensure you get the recommended ratio of macronutrients, food is classified into blocks of protein, carbs or fat. These blocks also promote nutritional balance in meals and snacks.

What Is a Block?

A block is a way of measuring your protein, carb and fat intake:

  • 1 carbohydrate block = 9 grams of carbs (excluding fiber)
  • 1 protein block = 7 grams of protein
  • 1 fat block = 1.5 grams of fat

The fat block represents the moderate amount of healthy fat — such as salad dressing — that you add to meals.

To determine how much of a specific food counts as a block, you can consult an online chart or books on the Zone Diet.

How Many Blocks Do You Need?

Your sex, body size and activity level determine how many blocks you need daily.

An average-sized woman needs 11 blocks daily of each macronutrient category — carbohydrate, protein and fat — while an average-sized man requires 14 blocks.

CrossFit provides a food chart to help you count your blocks. Alternately, you can use the Zone’s body fat calculator for a more precise calculation.

Once you know your block count, evenly divide your blocks into meals and snacks to ensure they have a balance of carbs, protein and fat.

An average-sized woman needs 3 blocks of each macronutrient at meals, compared to 4 blocks per macronutrient for an average-sized man. An additional 1–2 blocks of each macronutrient are eaten as snacks.

For example, a woman who needs 11 blocks of each macronutrient daily might eat:

BreakfastLunchSnackDinnerSnack
Protein3 blocks3 blocks1 block3 blocks1 block
Carbs3 blocks3 blocks1 block3 blocks1 block
Fat3 blocks3 blocks1 block3 blocks1 block

Block Examples

To plan a 3-block breakfast, you’d need 3 blocks each of protein, carbs and fat.

Consulting a block chart shows you that 1/3 cup of cooked oatmeal counts as 1 carb block. To get 3 blocks, you could eat 1 cup of cooked oatmeal.

Similarly, 1/4 cup of cottage cheese counts as 1 protein block. To get 3 blocks, eat a 3/4 cup of cottage cheese.

Lastly, 3 almonds count as 1 fat block. Therefore, eating 9 almonds would give you 3 blocks.

Weighing and Measuring Foods

Guidelines for the CrossFit-recommended Zone Diet give you permission to use the hand-eye method to estimate portions of proteins and healthy carbs.

That means selecting proteins, such as meat, that are about the size and thickness of the palm of your hand (3–4 cooked ounces), then making about two-thirds of your plate vegetables and a small amount of fruit.

However, you need to weigh and measure your dishes for at least one week to give you a better eye for estimating food portions.

Summary In the CrossFit-recommended Zone Diet, food is classified into blocks of the three macronutrients protein, carbohydrates and fat. An average-sized woman needs 11 blocks of each macronutrient per day while an average-sized man needs 14.

In the Zone Diet, foods are ranked as best choices if they have a low GI and are low in saturated fat and omega-6 fat. Foods higher in these indicators are thought to be more inflammatory and therefore ranked as fair or poor choices.

Examples of best-rated vegetables — which are generally non-starchy — and their block portions are (6):

Vegetable1 carbohydrate block equivalent
Asparagus12 cooked spears or 1 cup (180 grams)
Bell peppers2 whole peppers or 2 cups sliced (184 grams)
Broccoli1.5 cups cooked or 2.5 cups raw (230 grams)
Green beans1.5 cups fresh, cooked (187 grams)
Romaine lettuce10 cups chopped (470 grams)
Tomato1.5 cups chopped (270 grams)

Examples of best-rated fruits are (6):

Fruit1 carbohydrate block equivalent
Apple 1/2 medium-sized (91 grams)
Blueberries1/2 cup (74 grams)
Grapefruit1/2 medium-sized (123 grams)
Orange1/2 medium-sized (65 grams)
Pear1/2 medium-sized (89 grams)
Strawberries1 cup sliced (166 grams)

Examples of best-rated lean proteins include (6):

Protein1 protein block equivalent
Beef, grass-fed1 ounce cooked (28 grams)
Chicken breast1 ounce cooked, skinless (28 grams)
Cod1.5 ounces cooked (42 grams)
Cottage cheese1/4 cup (56 grams)
Salmon1.5 ounces cooked (42 grams)
Tofu2 ounces firm (56 grams)

Examples of best-rated fats rich in monounsaturated fat include (6):

Fat1 fat block equivalent
Almonds3 whole (3.6 grams)
Almond butter1/2 teaspoon (2.6 grams)
Avocado1 tablespoon (14 grams)
Guacamole1 tablespoon (15 grams)
Olive oil1/3 teaspoon (1.5 grams)
Olive oil and vinegar dressing1/3 teaspoon (1.5 grams) oil plus vinegar as desired

Additionally, people are encouraged to take an omega-3 supplement to help reduce inflammation.

Summary The Zone Diet recommended by CrossFit encourages plenty of non-starchy vegetables and a moderate amount of low-glycemic fruits, lean protein and healthy monounsaturated fats to control blood sugar and inflammation.

Though no food is completely off-limits, the Zone Diet encourages you to restrict or avoid certain foods, including:

  • High-glycemic fruits: Bananas, dates, figs, mangos and raisins.
  • Juice: Sugar-sweetened juice and 100% juice, such as apple, orange or grape juices.
  • Grain-based foods: Bread, dry cereal, crackers, muffins, pasta, pancakes and tortillas, especially if made with refined (white) flour.
  • Starchy vegetables: Winter squash, corn, peas, potatoes, sweet potatoes and legumes.
  • Sweets and desserts: Doughnuts, cookies, candy, pie, cake and ice cream.
  • Sugar-sweetened drinks: Soda, lemonade and energy drinks.

Grains, starchy vegetables, dried fruits and sugar-sweetened items use up your carb blocks in a small serving. If you eat any of the foods above, it’s crucial to measure and limit your portion sizes.

Summary To enjoy satisfying portions and get the most nutrition during a CrossFit program, limit sugary, high-glycemic fruits, starchy vegetables, legumes and grain-based foods while on the Zone Diet. Strictly reduce or avoid juice and sugar-sweetened foods and drinks.

Here’s an example of an 11-block menu, which would be appropriate for an average-sized woman (6):

Breakfast (3 blocks of each macronutrient)

  • 3 protein blocks: 3/4 cup (170 grams) of cottage cheese
  • 1 carb block: 1.5 cups (270 grams) of chopped tomatoes
  • 2 carb blocks: 1 cup (148 grams) of blueberries
  • 3 fat blocks: 9 almonds (11 grams)

Lunch (3 blocks of each macronutrient)

  • 3 protein blocks: 3 ounces (84 grams) of grilled chicken breast
  • 1 carb block: 1 cup (180 grams) of cooked asparagus
  • 2 carb blocks: 1/2 cup (99 grams) of cooked lentils
  • 3 fat blocks: 1 teaspoon (4.5 grams) of extra virgin olive oil to flavor vegetables

Afternoon Snack (1 block of each macronutrient)

  • 1 protein block: 1 large hard-boiled egg (50 grams)
  • 1 carb block: 2 cups (298 grams) of cherry tomatoes
  • 1 fat block: 1 tablespoon of avocado (14 grams)

Dinner (3 blocks of each macronutrient)

  • 3 protein blocks: 4.5 ounces (127 grams) of baked salmon with dill
  • 1 carb block: 1.5 cups (234 grams) of steamed broccoli
  • 1 carb block: 2 cups (380 grams) of sauteed collard greens
  • 1 carb block: 1 cup (166 grams) of strawberry slices
  • 3 fat blocks: 1 teaspoon (4.5 grams) of extra virgin olive oil to cook salmon and collard greens

Evening Snack (1 block of each macronutrient)

  • 1 protein block: 1 ounce (28 grams) of a mozzarella cheese stick
  • 1 carb block: 2 cups (184 grams) of bell pepper strips
  • 1 fat block: 5 small olives (16 grams)

Because of their low carb counts, some 1-block vegetable portions are large. You can eat a smaller amount if desired.

For more ideas, consult CrossFit’s website, where you can find 2-, 3-, 4- and 5-block meals and snacks.

Summary If you want to follow the CrossFit-recommended Zone Diet but aren’t sure how to start, there are many sample menus available online and in books about the Zone Diet.

Eating low-glycemic carbs — as recommended in CrossFit and the Zone Diet — is known to enhance glucose stores (glycogen) in your muscles, which are used to fuel exercise (7).

However, it’s uncertain whether a low-glycemic diet significantly improves athletic performance (7).

Though CrossFit’s founder and CEO, Greg Glassman, claims that his best performers follow the Zone Diet, published studies are limited.

The diet hasn’t been tested in a study of CrossFit athletes, but it was used for one week in a study in eight endurance athletes. While the study failed to demonstrate a performance benefit of the diet, it was also very small and short-term (8).

A small amount of research in non-athletes suggests that the Zone Diet may have health benefits.

Its carb guidelines could be helpful in preventing chronic diseases, such as obesity, heart disease and diabetes (9, 10, 11).

In a study in 30 people with type 2 diabetes who followed the Zone Diet for six months and supplemented with 2,400 mg of omega-3s daily, average blood sugar decreased 11%, waist size by 3% and an inflammation marker by 51% (12, 13).

Lastly, the diet’s emphasis on eating protein with every meal and snack — especially at breakfast and lunch — is increasingly recognized as a way to support muscle growth and repair, particularly as you age (14, 15).

Summary Though evidence of the CrossFit-recommended Zone Diet’s benefits in athletes is limited, it may reduce chronic disease risk and preserve muscle mass as you age. Plus, eating low-glycemic carbs may enhance glucose fuel stores in your muscles.

Certain aspects of the Zone Diet’s carb, protein and fat recommendations are of potential concern.

Firstly, some scientists question whether the moderately low number of carbs in the diet is enough for CrossFit athletes. Bear in mind that research to evaluate this concern is limited.

In a nine-day study in 18 athletes, those eating an average of 1.4 grams of carbs per pound (3.13 grams per kg) of body weight performed just as many repetitions in a CrossFit workout as those eating 2.7–3.6 grams of carbs per pound (6–8 grams per kg) of body weight (7).

Therefore, the carbohydrate levels of the Zone Diet may be adequate for CrossFit athletes — at least in the short term. Whether it supplies athletes with enough carbs over the long term isn’t certain (7).

Secondly, if you have a health condition that requires you to restrict protein — such as chronic kidney disease — the Zone Diet contains too much protein for you (16).

A third concern is the Zone Diet’s strict limits on saturated fats — particularly its encouragement of low-fat or fat-free dairy products, such as nonfat cheese.

Research increasingly shows that not all saturated fats are the same, and some saturated fat — such as that in dairy products — may have a neutral or even positive effect on health (17, 18, 19, 20).

Just as you would for any branded diet, beware of highly processed foods sold by the Zone Diet’s creators. Though they may claim to be scientifically justified, many contain refined grains, sugar and other unhealthy ingredients.

Summary It’s uncertain whether the Zone Diet provides enough carbs for all athletes. It is too high in protein for people who require protein restriction and may be too strict on limiting saturated fat, particularly from dairy foods.

CrossFit recommends the Zone Diet, which encourages a balance of lean proteins, non-starchy vegetables, nuts, seeds and low-glycemic fruit while limiting starch and refined sugar.

Though this diet hasn’t been studied in CrossFit athletes, it’s an overall healthy diet that may manage hunger and improve blood sugar and inflammation.

Many resources, including meal plans and recipes, are available online and in books to help you follow the diet. You can tweak it based on your individual needs.

Monitor your performance to see if the Zone Diet improves your CrossFit training.