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Nutrition for Athletes 101: What the Research Says


If you’re an athlete, your nutritional needs are different from the average person’s. Depending on your activity level, you may need more carbs (sometimes), protein, fat, vitamins, minerals, and water to fuel your activity and repair your muscles.

But there’s a lot of conflicting information out there about the best diet for athletic performance.

Some sources say you should “carb load” pre-workout, while others say you should “carb up” post workout to refuel your glycogen stores.

Some recommend lean protein like chicken breast and some swear by fattier cuts.

And what about a high-fat ketogenic diet? Does a keto meal plan work for athletes?

This article takes a comprehensive look at sports nutrition and will help you find a diet that helps increase your athletic performance while feeling your best.

Who is Considered an Athlete?

The term “athlete” is subjective, but for the purposes of this article, an athlete is a person who regularly engages in cardiovascular (aerobic) exercise, resistance (anaerobic) exercise, or both.

In other words, if you work out consistently, you’re an athlete. An athlete can be a dedicated professional or a dedicated gym go-er.

Elite athletes typically spend a large proportion of their time in training, while casual athletes might exercise a few times a week, or on weekends.

If you work out on a regular basis you’re also unusual, by the way. According to the CDC, 53.1% of American adults over 18 meet the Physical Activity Guidelines for aerobic activity, while 23.5% meet these guidelines for both aerobic and muscle-strengthening activities[*].

Whatever your activity level, it’s crucial to fuel your body with the right combination of carbs, protein, and fats that it needs to grow.

Here’s a breakdown of each macronutrient and how it fits into an athletic nutrition plan.

Carbohydrates For Athletes

When you eat carbohydrates — potatoes, rice, whole grain bread, legumes, candy bars, etc. — you digest them into sugar and send that sugar into your blood for fuel[*]. Your blood then transports the sugar to hungry cells.

Your cells absorb blood sugar (blood glucose) to create ATP, or usable energy. When your blood sugar is high, your body preferentially burns sugar for energy. This assumes you need more energy. 

If you’re not active enough to burn all that blood glucose for energy, your body stores it in one of two forms:

  1. Glycogen is your storage form of sugar. You can store about 500 grams of glycogen in your liver and muscle cells[*]. Glycogen stores help you power through long or high-intensity athletic efforts.
  2. Fat is the second storage option. If you eat more carbs than you burn, you store the excess as body fat. High blood glucose stimulates your pancreas to release the hormone insulin — which, if glycogen stores are full, shuttles blood sugar into adipose tissue (fat cells)[*].

Some say you need carbs to build muscle, but this information is outdated. In fact, a very-low carb diet was shown, in one clinical trial, to promote muscle growth better than a high-carb Western diet[*].

If you adapt to using fat as energy, you don’t need carbs for endurance either. Fat-adapted cyclists performed just as well on high-fat diets as cyclists on high-carb diets[*].

Carbs are a viable option for fueling your exercise, but they’re optional. You can run on fat just as well.

Protein For Athletes

Protein is made up of amino acids, which are the building blocks of muscle.

Working out breaks down your muscle tissue and leaves it in need of repair, which triggers protein synthesis. That’s when your muscles gather up amino acids and use them to repair muscle tissue that’s damaged by exercise, building it back up stronger than before. This is how your muscles grow.

If you work out regularly, you need to give your muscles a steady supply of protein so that they can repair and become stronger.

Excellent protein sources include meat (lean meat or fatty meat), fish, eggs, and whey protein isolate. Soy, peas, hemp, and rice have protein too, but protein from these plant sources is less bioavailable than protein from animal sources[*].

Fats For Athletes

Many athletes do well on a high-fat diet like a ketogenic diet. For instance, fat-adapting on a keto diet helps your body spare muscle glycogen, which can increase endurance and maximum power output[*]

And the amino acid leucine interacts with ketones (one of your main energy sources on a high-fat, low-carb diet) to preserve muscle mass[*]

Fat has other benefits too.

For instance, burning fat creates fewer free radicals than burning sugar does[*]. Free radicals cause oxidative stress that damages your cells[*], and running on fat instead of carbs minimizes oxidative stress.

Vitamins and Mineral Supplementation For Athletes

Carbs, protein, and fat — the three macronutrients — are only half of the nutrition equation. You also want to make sure you’re getting the right micronutrients, in the form of vitamins and minerals.

Here are some of the key micronutrients for athletes.

Vitamins for Athletes

Vitamin D

Vitamin D regulates more than a thousand biological processes in your body, and is essential for testosterone and human growth hormone production (for both men and women).

You can take a vitamin D supplement, or you can spend a few minutes a day in direct sunlight with your skin exposed and no sunscreen on. Your body synthesizes vitamin D from sunlight; just make sure you don’t stay out so long that you get sunburned.

While a little sunlight is great for you, if you push it to the point of sunburn you’ll increase your risk of skin cancer.

Vitamin B12

Vitamin B12 supports energy metabolism. The best sources are animal products, especially beef liver.


Folate is required for methylation, a process that helps you produce energy and detoxify harmful chemicals. Green vegetables are excellent sources of folate.


Niacin or vitamin B3, is another energy vitamin, and helps prevent exercise fatigue[*]. The best sources are animal products.

Vitamin E

Vitamin E is a critical antioxidant vitamin. The best sources are olive oil, avocados, spinach, nuts and seeds.

Minerals for Athletes


Magnesium helps you build muscle and supports the nervous system[*]. The best source is dark, leafy greens. You can also take a magnesium supplement each morning, with or without food. Aim for 400 milligrams of magnesium per day.


Sodium maintains your fluid balance and prevents dehydration[*]. Salt your food to taste with sodium chloride (table salt).


Potassium regulates blood pressure and fluid balance. The best potassium sources are avocados, carrots, and spinach.


Calcium helps with muscle contraction. The best calcium sources are dairy products.


Iron fuels the creation of red blood cells that carry precious oxygen to your tissues. The best iron sources are meat and spinach.

The minerals magnesium, sodium, potassium, and calcium are known as electrolytes.

Electrolytes carry electric charges — transmissions from nerve to nerve that occur most intensely during exercise[*]. You lose electrolytes when you sweat, so magnesium, sodium, potassium, and calcium are especially important if you’re working out a lot.

Pre-Workout Nutrition

When and what should you eat for optimal performance? Search the internet and you’ll find a wide range of answers to this question. Here’s a look at the different pre-workout and post-workout eating strategies and how each one works.

Carbohydrate Loading

Carbohydrate loading involves eating 5 to 12 grams of carbohydrate per kilogram body weight for each of the three to four days preceding an athletic event[*].

That’s a lot of carbs. For a 180 pound person, it’s around 400-1000 grams per day!

The idea behind carb loading is that all those extra carbs can boost your glycogen stores to fuel longer exercise efforts. Athletes often choose complex carbohydrate-rich foods like brown rice or whole grain pasta when they carb load.

According to one published review, carb loading does improve performance, but only for endurance efforts longer than 90 minutes[*], and only by a magnitude of about 2-3% improvement.

That 2-3% difference might be significant for an Olympic athlete — but for the average active person, it’s pretty negligible, and the massive spike in blood sugar and fat gain that comes from eating an extra 1600-4000 calories of carbs a day probably isn’t worth it.

However, you may find that having a few carbs an hour before your workout can help you push through a particularly difficult gym session or competition.

You can even do this when you’re on keto, using a variation called a targeted ketogenic diet. Many female athletes do especially well with having a few carbs before a workout.

Pre-Workout Protein and Fat

Fat and protein are good pre-workout snacks. Protein will give your body the building blocks for repairing and growing muscle, and fat is an excellent source of fuel, especially if you’re fat-adapted.

You might also eat some fat before a workout for extra energy. One popular pre-game snack in the keto community is Boosted Coffee — a combination of coffee, grass-fed butter, and MCT oil.

Post-Workout Nutrition

As with pre-workout nutrition, post-workout protein and fat are your friends.

To build muscle, simply consume a high-protein meal either before or after the workout. The timing isn’t so important[*]. Just eat your protein within an hour or two of the session.

For cardio workouts, you have more flexibility. If you aren’t fat-adapted on a low-carb diet, you may want to eat 100-150 grams carbs post-workout to replenish your muscle glycogen. But since keto spares muscle glycogen, this strategy is unnecessary on a ketogenic diet.

For all athletic nutrition — before or after exercise — strive to eat nutrient-dense foods like leafy greens, cruciferous vegetables, avocados, meat, and olive oil. Skip the sugary sports drinks and other energy drinks. For more keto-friendly guidance, check out this post on the 10 Best Post-Workout Keto Foods.

Keto Nutrition For Athletes: 5 Things To Know


Athletes have greater nutritional demands than sedentary people do, and there are a few unique aspects to eating a keto diet as an athlete. Here are the main areas athletes need to focus on:

#1: Energy Management

Exercising expends more calories than sitting or sleeping. Because of this, athletes need to eat more.

Ideally, you want to eat as many calories as your metabolism burns. This is called energy balance, and it’s a good strategy for maintaining a stable weight.

Alternatively, if you want to gain weight (muscle), you’ll want to eat an excess of calories. To lose weight, it’s probably wise to be at a slight caloric deficit.

A common issue for athletes is overeating after an event. Unfortunately, this “I earned it” feast can interfere with weight loss and performance goals.

Keto can help you curb cravings by reducing your main hunger hormone, ghrelin[*]. Keto suppresses appetite, leaving you satiated and less likely to overeat.

#2: Hydration

Humans are mostly made of water, and your body needs plenty of H2O to function properly.

If you’re athletic, you need even more water to replace lost sweat. A common recommendation is to drink half your body weight in ounces per day. But if you’re still thirsty — drink more.

Along with water, electrolytes — the minerals potassium, magnesium, sodium, calcium, and chloride — are crucial for hydration. They help you maintain fluid balance, contract your muscles, and allow your nerves to fire[*].

If you’re keto, you may want to take a high-quality electrolyte supplement, as keto athletes tend towards electrolyte deficiency.

#3: Recovery

After a hard workout, your body needs time to repair. The amount of repair you need depends on how badly you beat yourself up.

There are several ways to track your recovery. One is muscle soreness. If your muscles are no longer sore, you’re ready to work out again.

A keto diet can help you recover faster than you would on a higher-carb diet. Ketosis decreases oxidative stress and increases antioxidant status in athletes[*]. Less oxidative stress means less inflammation, which leads to faster muscle recovery.

#4: Nutrient Deficiency

Probably the most common nutrient deficiency for athletes is electrolyte deficiency. Athletes lose magnesium, calcium, potassium, chloride, and sodium in their perspiration — and it needs to be replaced.

Beyond electrolytes, however, there are countless other deficiencies that could hinder athletic performance.

Eat plenty of vegetables and the occasional organ meat to make sure you’re getting a full range of micronutrients on keto. As long as you’re eating several servings of vegetables a day, you’ll hit your full range of micronutrient needs.

Still not sure about your micronutrient stores? You can try a high-quality supplement.

#5: Not Enough Protein

Of all the macronutrients you need as an athlete, protein is the most crucial. Without adequate protein, you can’t build or repair muscle.

How much protein do you need? That depends on your activity level. Here are the published recommendations[*]:

  1. High activity — 1.6 grams / protein per kilogram body weight (100 grams protein for a 140 pound person)
  2. Moderate activity — 1.3 grams / protein per kilogram body weight (80 grams protein for a 140 pound person)
  3. Sedentary — 1 gram / protein per kg body weight (60 grams protein for a 140 pound person)

Elite athletes can probably go higher. In fact, up to 2 grams protein / kilogram body weight a day — around 160 grams protein for a 180 pound person — is considered safe[*].

What about protein on keto? The ketogenic diet is about 60% fat, 30% protein, and 10% carbs by calories. That allows plenty of room for 100-200 grams of daily protein for a highly active person.

The Takeaway: Keto Diet for Athletes

Good nutrition is a fundamental part of athletic performance. If you’re going to work out or compete, you’ll do a lot better with high-quality fuel.

Every athlete needs protein, but depending on your goals and tastes, you can fuel your workouts with different combinations of carbs and fats. You may find you do well on a ketogenic diet, especially if you feel sluggish or foggy after eating carbs. If you want to give keto a try, check out this simple beginner’s guide to keto.

Keto or not, make sure you get enough micronutrients like magnesium, potassium, vitamin D, vitamin B12, and folate.

Hydrate, sleep, recover, eat nutrient-dense foods, and strive for energy balance. The rest will handle itself.

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