You just finished a run, elliptical session, or aerobics class. You’re hungry and wonder: What’s the best way to refuel? To maximize muscle growth, it’s usually important to consume a protein-filled snack immediately after a strength training workout. But what you should eat after a cardio session depends on what type of cardio you completed, how long and intense your session was, and what you ate before exercising.
Why Protein Matters After Cardio
While cardio can build a small amount of muscle, you’ll need to incorporate strength training to really see muscle gain. The real benefit of cardio exercise is that it burns calories, which can help you to maintain or lose weight, when combined with the right diet.
After a cardio workout, it’s generally a good idea to eat both protein and carbs for optimal recovery, according to Allison Knott, RDN, a sports dietitian with Anew Well Nutrition.
Doing a cardio workout-such as going for a run, cycling, or rowing-also puts your body in a depleted state, Ehsani says. When we work out, we use glucose for fuel, which we get from the carbs we eat. Afterwards, our bodies are running low on glycogen and our muscles are broken down. “This happens more in longer or more intense cardio sessions,” she reiterates. “Eating protein right after cardio helps begin the repair and rebuilding of muscle fiber and supports replenishment of glycogen stores.”
Nutrition Guidelines to Follow
There are some nutrition guidelines you can follow to make sure you’re getting the most out of your post-workout meal. If you did less than an hour of cardio at a low or moderate intensity, you probably did not deplete all of your muscle’s energy stores. Energy is stored in the muscle as glycogen, a chain of sugar molecules. Your body uses fat and sugar to fuel aerobic exercise. If you haven’t eaten or have done a longer and/or more intense cardio workout, be sure to eat within 45 to 60 minutes to restore muscle glycogen. This is primarily important for those who will be exercising again soon.
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Here are the current recommendations from a study published in the Journal of International Society of Sports Nutrition:
- If you fasted before you trained, you should consume a combination of protein and carbohydrates shortly after your workout to promote muscle growth.
- If you haven’t eaten for four to six hours before a workout, you may also benefit from a protein- and carbohydrate-rich meal immediately after a workout.
- If you ate one to two hours preworkout, that meal may be sufficient to promote muscle building even after exercise. This is because the muscle-building amino acids broken down from your food remain in the bloodstream for up to two hours after eating.
Post-Cardio Nutrition Based on Workout Type
With this in mind, here’s what you should eat after different cardio workouts.
Moderate Intensity Cardio
If you’re supplementing your strength training routine with a standard 30- to 45-minute moderate intensity cardio session (like a 5K run or Zumba class), you should focus on replenishing lost fluids afterward. Although your heart rate is elevated and you’re sweating, your caloric expenditure was still relatively low. After this type of cardio workout, drink at least 8 ounces of water. Drink more if you weren’t properly hydrated before exercising. You can substitute coconut water, but stay away from sports drinks like Gatorade that provide an unnecessary amount of sugar for a shorter workout.
High-Intensity Interval Training (HIIT)
HIIT workouts, like sprints or a cycling class, combine short bursts of all-out activity with short periods of rest. This type of cardio, called anaerobic exercise, is an intense workout. You’ll burn more calories for a given amount of time, and you’ll experience the afterburn effect, or excess post-exercise oxygen consumption (EPOC).
EPOC is the amount of oxygen required to return the body to its resting state. HIIT sessions stimulate a higher EPOC because you consume more oxygen during them. This creates a larger deficit to replace post-workout. It means you’ll continue to burn calories even after your HIIT session is over. The amount of effort your body exerts during and even after an HIIT workout is greater. So what you refuel with is more important than it is a steady state cardio session of the same length. On top of at least 8 ounces of water or coconut water, choose a small meal with a combination of protein and carbohydrates. According to the Academy of Nutrition and Dietetics, a carbohydrate/protein ratio of 3:1 in a post-workout meal is appropriate for most people.
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Protein will help rebuild muscles, while carbohydrates will replace muscle glycogen stores. This will replenish your energy. Examples of these types of meals include:
- A protein shake with one scoop of protein and a banana
- A glass of chocolate milk
- Greek yogurt with berries
- Tuna on whole-wheat bread
Endurance Training
If you’re training for a race and putting in some serious cardio miles, those hours of exercise require thoughtful refueling, too. After your workout, drink plenty of water or choose a sports drink with electrolytes, like Gatorade. These drinks help replace fluids and sodium lost through sweat. Next, choose a small meal with a carbohydrate/protein ratio of 3:1. Some examples include cereal and milk, a bagel with eggs, or a protein shake with added fruit.
Benefits of Consuming Protein After a Cardio Workout
Whether you’ve just finished laps in the pool or capped off a HIIT session, your body likely needs more than just hydration and carbs. There are quite a few reasons why protein deserves a spot in your post-cardio recovery routine; chief among them, it can help you recover faster, preserve lean muscle, and bring you back to life after a grueling cardio workout.
Specifically, here are a few benefits of refueling with protein after cardio:
- It promotes muscle recovery: After more intense cardio sessions like miles-long runs, endurance rides, or vigorous rows, protein helps facilitate and improve the recovery process so you don’t wake up as sore or fatigued post-workout, Ehsani says.
- It prevents muscle breakdown: After long, hard, or fasted workouts like endurance training, consuming protein can help prevent your muscles from breaking down thanks to its muscle-repairing abilities. “Eating enough protein overall as well as meeting total calorie needs is also essential for this process,” Knott says.
- It replenishes energy levels: When eaten with carbs, protein can help prevent a post-cardio energy crash and stabilize blood sugar levels, promoting satiety.
Protein for Weight Loss
Consuming more protein can help you feel full longer, build lean muscle, and support your metabolism. Different types of protein powders contain different nutrients.
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Protein is an important nutrient for weight loss. Getting enough protein may support a healthy metabolism and reduce your appetite. It may also help you lose body fat without losing muscle.
Protein shakes are a convenient way to add more protein to your diet. They’ve even been shown to aid weight loss.
How Protein Helps with Weight Loss
Protein has been shown to help decrease hunger and appetite.
One key reason is that protein generally helps you feel full for longer. This is partly due to the release of fullness hormones GLP-1 and PYY. Studies also show that higher protein intake may result in less hunger throughout the day.
In one small 2015 study, a high protein breakfast helped older women consume up to 135 fewer calories later in the day, compared with a low protein breakfast or skipping breakfast.
One 2016 meta-analysis of five studies also connected high protein intake and increased fullness. However, review authors caution that factors like body weight, eating behavior, and other health issues all play a role in the sensations of fullness.
Furthermore, another review published in 2020 reports that ingesting more than 35 grams (g) of protein at once appears most effective for effects like less hunger, a reduced desire to eat, and greater feelings of fullness.
Only a few studies have looked at protein shakes and appetite specifically. One 2019 study with nine young women with obesity found that a whey protein drink actively reduced appetite.
In a 2021 study, participants given a high protein shake before their workout reported feeling less hungry after exercising than when given a lower protein shake with an equal number of calories.
Thus, while results are promising, numerous factors may affect the influence of protein shakes on appetite and hunger.
Protein and Metabolism
A high protein diet, especially when combined with strength training, can help build muscle. Because muscle aids metabolism and energy production, building muscle is a great way to keep your metabolism healthy.
This is especially true if you follow a calorie-restricted diet to lose weight.
That’s because extreme calorie restriction may result in muscle loss and fat loss. This loss of lean muscle may slow your metabolism, making it easier to regain weight once you stop the restrictive diet.
Conversely, eating sufficient amounts of protein, combined with strength training, may help prevent this muscle loss and resulting metabolic slowdown.
A 13-week study in older adults with obesity found that those who consumed an extra 20 g of protein weekly (in the form of a shake) gained 2.8 pounds (lb), or 1.3 kilograms (kg), more muscle mass than those who ate less protein.
Plus, in a 6-week study, participants followed either a low or high protein diet, which included shakes. Each diet was calorie-restricted. Notably, participants following the higher protein plan gained 2.4 lb (1.1 kg) more muscle and lost 2.9 lb (1.3 kg) more fat.
Your body also uses more energy to digest protein than it does fat or carbs, which means your body burns more calories in the process. This effect, called the thermic effect of protein, may provide a slight metabolism boost.
Protein and Fat Loss
Although few studies use protein shakes specifically, researchers generally agree that high protein diets are an effective way to lose weight and body fat.
A 14-week study gave women with overweight or obesity a resistance exercise program alongside a high carb or high protein, calorie-restricted diet. Those in the high protein group lost 1.7 times more body fat than those in the high carb group.
In a 12-week study, women with a moderate weight but high body fat percentage followed either a high or standard protein diet. Those on the high protein diet lost an additional 3 lb (1.4 kg) of body fat and around 1 inch (2.2 centimeters) in waist circumference. The participants in the high protein group also retained significantly more muscle mass than those on the standard protein diet.
A 2020 review further suggests you can minimize weight regain by following a high protein diet in the first 3-12 months after losing weight. However, long-term studies must confirm whether this effect lasts beyond the first year.
Still, a small 2017 study found that when participants with excess weight drank low sugar protein shakes as part of a diet program, their weight loss improved.
Protein Shakes and Weight Management
Because so many lifestyle and ingredient variables are involved in weight loss studies, it’s hard to draw a direct connection between protein shakes and weight loss.
Protein’s effect on metabolism, appetite, and muscle mass may also help prevent regaining weight once you’ve lost it.
This effect should apply whether you get protein from shakes or whole foods.
One 2015 review suggests that higher protein intakes of 25-30 g per meal improve both weight loss and weight management. However, researchers caution that full adherence to a high protein diet, plus other lifestyle factors, is usually necessary.
Similarly, studies suggest that high protein diets result in less short-term weight regain after you lose significant amounts of weight. All the same, more studies are needed.
Considerations for Protein Intake
Makers of protein shakes may say that their products help lower body fat or promote weight loss. Some studies find that consuming a higher than usual amount of protein in your diet may offer benefits. For example, eating or drinking products that are high in protein may help you lower body fat, keep lean muscle, feel full and lose weight. But evidence is limited.
Replacing meals with protein shakes may help you lower your daily calories, which can help you lose weight. But in time you'll need to start eating solid food again. Eating solid food may cause excess weight to return if you don't make smart food choices. Since protein has calories, consuming too much can make it harder to lose weight.
The Dietary Guidelines for Americans state that an average adult needs about 46 to 56 grams of protein a day. This amount depends on your weight and overall health. Keep in mind that the key to losing weight is burning more calories than you consume. Also add physical activity to your daily routine. Aim for about 30 minutes of activity, such as brisk walking, most days of the week.
Protein Shake Options
Protein shakes are made by mixing protein powder with water or another liquid, plus optional other ingredients.
Although most people don’t need protein shakes to meet daily protein requirements, protein shakes can be convenient if you have limited access to high protein foods or experience trouble meeting your needs through food alone.
You can buy protein powder and mix it yourself or purchase premade liquid shakes.
Types of Protein Powder
- Whey protein: quickly absorbed, dairy-based, and contains all nine essential amino acids
- Casein protein: slowly absorbed, dairy-based, and provides all essential amino acids
- Soy protein: plant-based and offers all essential amino acids, plus soy isoflavones that may provide some health benefits
- Hemp protein: plant-based, contains all essential amino acids, rich in omega-3 and omega-6 fatty acids, and has a high arginine content
- Rice protein: plant-based but lower in the essential amino acid lysine
- Pea protein: plant-based and less allergenic alternative to soy and whey protein, but lower in the essential amino acids cysteine and methionine
Certain protein powders and drinks contain a mix of protein types.
For example, many plant-based brands combine types to diversify the amino acid profile. Some dairy-based protein powders combine whey and casein to provide immediate and longer lasting effects on muscle synthesis.
Which Type of Protein Is Best?
Different types of protein may affect your body in distinct ways.