Here's How Long Protein Actually Stays In Your Body

The macronutrient protein serves many functions in your body, from building tissues and bones to powering many of your body's functions. Amino acids are the building blocks of protein. Your body can only make 11 of the 20 amino acids necessary to build and repair its tissues (per Gainful). That's why you need to get an adequate amount of protein in your diet every day. At a minimum, you'll need 0.8 grams of protein per kilogram of body weight per day. For someone weighing 150 pounds, that's about 54 grams of protein. Older adults need a little more protein, up to 1.2 grams of protein per kilogram of weight.

When you eat something with protein, it begins breaking down into peptides in your stomach. Your small intestine breaks these peptides down into amino acids so your bloodstream can pick them up and direct them to various parts of your body. This digestive process can occur between 30 minutes and four hours, depending on the type of protein you consume (per Kos).

Some proteins can be digested within 30 minutes or up to two hours. While they might be great for a post-workout recovery, these proteins don't help you feel full for too long. Whey, pea, and collagen protein powders are fast-digesting proteins (per Vidafuel).

Other proteins can take up to four hours to completely digest in your body. These slower-digesting proteins include some plant-based proteins and casein. Proteins found in whole foods also digest a little more slowly. Slow-digesting proteins will help you feel fuller for longer and also help feed your muscles while you sleep.

The speed at which protein digests through your system can also depend on whether or not you consume your protein with fats and carbohydrates. If you have protein on an empty stomach, it will digest faster. Fats and carbs with your protein will slow down the digestive process. However, your individual metabolism, activity level, and body composition can make the digestion process faster or slower (per Kos).

Remember that these amino acids don't stay very long in your body. Once this protein reaches your bloodstream, the amino acids can stay for as long as six or seven hours. Most of the amino acids are typically absorbed within two hours (per Kos).

Because your body can only absorb 8 to 10 grams of fast-digesting whey protein in an hour, you'll need to consume a little bit of protein at each of your meals. You can aim for about 0.4 grams of protein per kilogram of body weight per meal to get a continual supply of amino acids in your bloodstream. Some digestive enzymes can help your body better absorb protein, so you can increase the levels of amino acids in your blood (per Gainful).

Even though your stomach and small intestine have extracted the amino acids from the protein, it doesn't mean that your food is done digesting. By the time your food makes it through your colon, it could be up to 72 hours later, according to Healthline.