How much protein can your body absorb?
Proteins are the main building blocks of your body used to repair and maintain your body tissues. If you’re trying to consume more protein in an effort to build muscle or lose weight, you might find yourself attempting to squeeze in as much protein into a single meal as possible. But there is a limit to how much protein the body can properly absorb per day, as well as a limit to how much protein the body can absorb in one sitting.
You won’t be able to eat — and more importantly, properly absorb — the amount of protein you need per day in one meal. You have to space out your protein intake throughout the entire day.
So just how much protein can the body absorb? Below, we’ll discuss daily protein requirements based on weight, gender and age. Then, we’ll delve into just how much protein your body can absorb per day (and per sitting) and give you tips for maximizing your protein absorption.
How much protein can you have a day? Protein recommendations based on weight, sex and age
The amount of protein you need each day depends on a number of factors — the most significant being your body weight, sex and age.
If you exercise often or are working toward a specific fitness goal, such as building muscle or weight loss, protein should make up around 20-25% of your daily energy intake. 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 range is 0.8-1 grams per kilogram for healthy adults, and 1-1.2 grams per kilogram for an elderly person. For example: An active young woman who weighs around 150 pounds would need a minimum of 54 grams of protein per day following that guideline.
Sex is also a factor in determining how much protein a person should consume per day. Generally speaking, young men need slightly more protein per day than most young women — especially when trying to build muscle. All men, regardless of activity level, should consume at least 56 grams of protein every day; however, a 160-pound man working to increase his lean body mass would actually want to consume closer to 100+ grams of protein every day.
The minimum amount of protein you should consume per day also increases with age. As mentioned above, the range is 0.8-1 gram of protein per kilogram for young adults, but it’s 1-1.2 grams per kilogram for an older person. As a 2014 article published in Sports Health titled “Muscle Changes in Aging” notes, muscle tissue changes in many ways with age, so maintaining healthy muscles is especially important as you grow older. Consuming more protein can effectively help prevent sarcopenia, the age-related decrease in lean muscle mass. That’s why older people have a higher recommended minimum amount for protein intake.
But these are just the minimum requirements based on weight, sex and age. What about the maximum protein dosages? What’s the maximum amount of protein the body can absorb?
For the active young adult, a 2018 study published in the Journal of the International Society of Sports Nutrition concluded that to maximize anabolism (the process by which proteins are formed from amino acid), a healthy person can 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 both men and women who want to maximize their protein intake, 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 1.6 grams per kilogram per day — an amount the body is able to effectively absorb.
Maximizing protein consumption: How much protein can your body absorb in one hour? Can the body absorb more than 30 grams of protein in one sitting?
The authors of that same Journal of the International Society of Sports Nutrition study note that muscle protein synthesis — the naturally occurring process in which protein is produced to repair muscle damage caused by exercise — is maximized at a protein dose of around?20 to 25 grams. That means the most your body can absorb in one sitting is around 25 grams of protein. In this case, “one sitting” refers to the time over the course of 1.5-2 hours. Broken down by hour, the body can absorb fast-digesting proteins like whey at a rate of roughly 10 grams per hour, per the study.
But what happens when you consume more than 25 grams of protein in one sitting? Just because you can technically consume more protein than that doesn’t mean your body will utilize it for muscle growth. Consuming 30+ grams of protein in one sitting 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 excess protein will either go to other parts of your body, or into the toilet.
If maximizing protein absorption is your goal, the best way to achieve this is by spreading out your protein consumption throughout the day. So instead of attempting to squeeze in your daily protein requirements in a single meal, try consuming your protein throughout four or more meals a day and opt for a fast absorbing protein when possible. The fastest digesting proteins are the ones 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 for the body to break down. That said, there is a possible downside to whey that can render it a non-option: Whey protein contains lactose and is a by-product of cheese production, which is a problem for people who are vegan or lactose intolerant. Luckily, there are a few fast absorbing protein options for those with dietary restrictions. 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 grams of whey protein, bodybuilders can rest assured: Pea protein can deliver similar results in terms of aiding muscle growth and muscle building.
In certain situations, protein is also better absorbed by the body if you take digestive enzymes at the same time, per a study published in the Journal of the International Society of Sports Nutrition. The small intestine is the major site of protein digestion by proteases (enzymes that cleave proteins), and a digestive enzyme is a complex protein made by your body to help break down food into smaller molecules so they can be absorbed. There are a number of supplements available that aid your digestive system if you lack those enzymes, so you’re better able to properly absorb the macronutrients you need, like protein. Trypsin, for example, is a digestive enzyme that breaks down protein so it can be made into amino acids.