Protein absorption rate chart - Ask an RD

Proteins are the main building blocks of your body used to repair and maintain your body tissues. They are made of smaller substances called amino acids. There are 20 amino acids; however, your body can only make eleven of them. The other 9 are called essential amino acids, and you can only get them through your diet. 

This is why it’s important that you not only get an adequate amount of protein throughout your diet, but that it is also efficiently absorbed. Just because you consume protein doesn’t mean you’re properly absorbing 100% of that protein. There is a limit to how much protein the body can properly absorb at once. The maximum rate that a fast absorbing protein like whey can be absorbed is about 8-10 grams per hour. That means you need to space out your protein intake throughout the entire day — you won’t be able to eat and properly absorb your daily requirement for protein in just one sitting.

How much protein can the body absorb at once?

The general rule for calculating the minimum amount of protein that you need is 0.36 grams of protein per pound that you weigh (or 0.8 grams per kilogram that you weigh). The Recommended Dietary Allowance (RDA) range is 0.8-1 gram per kilogram for healthy adults, and 1-1.2 grams per kilogram for an elderly person. 

As for the maximum protein dose in one sitting, a 2018 study published in the Journal of the International Society of Sports Nutrition concluded that to maximize anabolism — aka the process by which proteins are formed from amino acids — one should consume protein at a max intake of 0.55 grams per kilogram per meal across four meals. This aligns with a daily intake of 2.2 grams per kilogram per day, which is on the upper end of what’s generally recommended. For most people, the study suggested aiming for a target intake of 0.4 grams per kilogram per meal across a minimum of four meals in order to reach a minimum of 1.6 g per kilogram per day. 

The study also notes that muscle protein synthesis — the naturally occurring process in which protein is produced to repair muscle damage caused by exercise — is maximized at protein doses of around?20 to 25 grams throughout an entire day of eating. 

Can the body absorb more than 30 grams of protein? What percentage should my protein intake be?

As you know, there’s a limit to how much protein your body can efficiently absorb at once. Per the study referenced above, muscle protein synthesis is maximized at a dose of ?20 to 25 grams of protein. Trying to absorb closer to 30 grams of protein (or beyond) won’t give your muscle any “extra boost.” If your muscles receive more than 35 grams of protein at a single time, they already have more than enough of the building materials they need. That means that extra protein will either go to other parts of your body, or excreted through the urine. 

To better calculate your protein requirements, you can divide your diet into macronutrient categories and have a specific percentage of your total calories per day dedicated to protein. Typically, consuming around 20-25% of your calories from healthy protein sources is the sweet spot if you are looking to add muscle.

If you’re exercising regularly in an effort to lose weight, your protein needs are likely around a macronutrient breakdown of 30% protein, 40% carbohydrate and 30% fat. 

But if your focus is on muscle building, then you’ll want to consume more calories to help stimulate that desired muscle growth and focus more on carbohydrate consumption, especially post-exercise. While you're working to build muscle with exercise, protein should make up 25% of your total calories. That makes your macronutrient breakdown 25% protein, 55% carbohydrate and 20% fat. Try sticking with 1-1.5 grams protein per pound bodyweight, but be sure to add more carbs if you want to gain more muscle mass. To up your carb intake, you can make healthy carbs like berries, bananas, quinoa, sweet potatoes or other whole grains part of your post-workout meal or post-workout snack. Most bodybuilders and professional athletes go for carbs that are low on the glycemic index but high in fiber, such as beans, whole grains, and vegetables. If your end goal is to build muscle, consider adopting a similar diet. 

If you’re an endurance athlete who bikes long distances, runs marathons or engages in resistance training, your body is burning through a lot of fuel during your workouts. This means you’ll need higher stores of carbohydrates than you would if you were mainly strength training or doing HIIT workouts. Your ideal protein consumption during your endurance training might be closer to 0.6 to 0.9 grams protein per pound bodyweight instead of 1-1.5 grams protein per pound bodyweight, making your macronutrient breakdown 20-25% protein, 55-60% carbohydrate and 20% fat. 

Strength athletes, such as a gymnast or someone who performs calisthenics, are the ones who actually need closer to 35% of their calories to come from protein. If that’s you, then you should follow a higher protein, lower carbohydrate diet with a breakdown of 30-35% protein, 25-40% carbohydrate and 25-40% fat.

How do you get maximum protein absorption?

The best way to get maximum protein absorption is to spread out your protein consumption throughout the day. So instead of trying to cram in 40+ grams of protein over the course of one or two meals, try consuming your protein throughout four or more meals/snacks a day. 

If you’re searching for the fastest absorbing protein, the fastest digesting ones are the proteins that have been separated from their whole food source and turned into protein powder. Protein powders are usually consumed as a liquid without much fiber or fat, and generally speaking, liquids digest faster than whole foods. So that means protein powder supplements poured into protein shakes or smoothies will be absorbed more quickly than most dietary protein. Whey protein hydrolysates are usually the fastest digesting of all supplements because hydrolysates are processed further than whey protein isolate or whey protein concentrate. The extra processing makes hydrolysates even easier to break down.

Digestive enzymes are complex proteins made by the body to help break down food into smaller molecules so they can be absorbed.The small intestine is the major site of protein digestion by proteases, digestive enzymes that divide protein particles. While these are naturally produced in the body to aid with overall digestion in most individuals, diseases of the stomach and small intestine can reduce the number of enzymes produced, causing malabsorption of amino acids. There are a number of supplements on the market that can aid digestion if needed, so you can properly absorb nutrients like protein. Trypsin, for example, is a digestive enzyme that breaks down protein so it can be made into amino acids.

Digestive enzyme supplements may include one or a combination of multiple digestive enzymes, and some are sold in conjunction with probiotics. If you take a digestive enzyme with your protein, you’ll get higher amino acid levels in your blood. That means you’ll have more amino acids available to your muscles and other tissues, which is key for making the most of your protein. 

But if you’re vegan or have dietary restrictions, it’s important to note that some supplemental digestive enzymes are made from a pig or cow source. Common side effects of digestive enzyme supplements can also include constipation, nausea, cramps and diarrhea, so as always, be sure to speak with your doctor before incorporating a new supplement into your diet or wellness regimen.

Getting those amino acids: The best protein powder for maximum absorption

A fast absorbing protein is a protein that can be absorbed within a few hours so the body is able to utilize it faster to aid in processes like muscle protein synthesis. So then what is the fastest absorbing protein? 

Whey protein is the most popular fast absorbing protein. Its absorption rate has been estimated at roughly 10 grams per hour. At this rate, it takes just 2 hours to fully absorb a 20 gram-dose of whey. A commonly recommended protein powder dosage is 1–2 scoops (around 25–50 grams), so if you consumed 20 grams of whey protein around the time of a workout, that means your body would be able to utilize that protein within two hours of exercising. This is an especially fast rate of absorption compared to other proteins.

While whey protein powder is arguably the best protein powder for maximum absorption, there is a possible downside: Whey protein contains lactose and is a by-product of cheese production, which is a problem for people who are vegan or lactose intolerant. Thankfully, there are a few fast absorbing protein options for those with dietary restrictions, including pea protein. Of those most common vegan or plant proteins (pea protein, soy protein, brown rice protein, hemp protein and other seed, nut, or legume proteins), pea protein has the fastest absorption rate. 

Although it’s not quite as fast absorbing as whey, pea protein has proven it can deliver similar results: In a 2015 study published in the Journal of the International Society of Sports Nutrition, male participants between the ages of 18 and 35 followed the same 12-week upper-body lifting program. One group supplemented with 25 grams of pea protein twice a day, and another took the exact same amount of whey protein. Each 25 grams of protein from pea protein delivered around two grams of leucine, one of the 3 branched chain amino acids (BCAAs) that stimulates protein synthesis. Whey delivered 2.65 grams of leucine, but both the pea protein and the whey protein fell right in the middle of the optimal leucine range. Researchers recorded biceps muscle thickness at the beginning and end of the study, and at the end of the 12 weeks, both groups showed identical increases in biceps muscle thickness and both pea protein and whey protein types showed greater results than placebo. This study suggests that as long as a person supplementing with pea protein gets sufficient amounts of leucine, pea protein absorbs and can help build muscle tissue in a comparable way to whey.

On the other end of the spectrum is casein protein. Casein is a slow digesting protein. During cheesemaking, special enzymes are added to heated milk, which cause the casein in the milk to coagulate, or change to a solid state. The curds of casein are then able to be used in food products or dietary supplements. Although casein and whey protein are both derived from milk, the body absorbs them very differently. Your body breaks down protein into amino acids, which stay in your bloodstream until they’re absorbed. When a person consumes casein, levels of these amino acids stay elevated in the blood for about 4-5 hours (whereas in whey, these levels are elevated in the blood for about 90 mins). That’s because casein forms curds once exposed to the acids in your stomach, just as it does in cheesemaking. These curds actually lengthen your body’s digestion and absorption processes. By taking longer to digest, casein protein is able to provide the body with a slow and steady release of amino acids rather than releasing amino acids quickly.

Finding a protein powder that fits your needs

Looking for your perfect protein powder? Gainful can help. Gainful allows you to create a custom-made protein powder that aligns with your goals, so you can get exactly what your body needs for proper protein absorption and digestion. 

First, head here to take our quiz. Using your answers, Gainful will figure out what type of protein best suits your body composition and overall goals, whether that’s whey protein, casein protein or a blend of plant-based proteins. You can add your own personalization, then we’ll deliver everything you need in the perfect amounts, making sure you’re getting the high quality protein necessary to achieve your goals. And as part of your Gainful subscription, you’ll also have a dedicated Registered Dietitian on-hand to answer any lingering questions you may have about protein absorption rate. 

Gainful wants to make it easy to maximize your protein absorption and get the most out of your protein powder.