How much protein can your body digest and use at a time? If you you eat the right amount of protein at every meal you’ll supposedly hit the sweet spot – maximum muscle growth and satiety (fullness) without wasting food or money. General guidelines based on short term trials and one cross-sectional study suggest adults need regular meals including 25 – 45 grams of protein per meal to maintain or build muscle mass and maximum strength (1, 2, 3). However, it is possible that more protein per meal may be beneficial in some instances while the per meal amount might not matter very much in others. Your body can and will digest all of the protein you eat in a sitting (it might take a while) and it doesn’t just discard any excess that isn’t used to build structures in the body.

In this article I’ll cover:

1. Why we should we focus on a “per meal” dose of protein;
2. What happens to “leftover” protein;
3. What influences protein requirements;
4. How you can estimate your protein needs.

Does the Amount of Protein Per Meal Matter?

In a really cool study conducted by well-known protein scientists, the minimum amount of protein per meal found to maximally spike muscle growth was 0.11 grams per lb. of body weight in younger adults and 0.18 grams per lb. of body weight in older adults (over 71 years of age) (2). Older adults need more protein due to a decline in muscle response to protein intake that occurs with age. In addition to a minimum, there is an upper limit of protein intake; anything beyond this threshold dose will not be used to build muscle. For example, one study examined 4 ounces of beef containing 30 grams of protein compared to 12 ounces of beef containing 90 grams of protein. The larger serving did not lead to a greater increase in acute muscle protein synthesis compared to the 4 ounce serving (4). So now we know we need some protein, but not 90 grams in one sitting. In another study, 40 grams of protein stimulated the processes underlying muscle growth and repair to a greater extent than 20 g after a whole body workout (9). However, we still don’t know what the minimum upper limit is, beyond which higher intakes do not lead to increases in muscle mass or muscle functioning over time (5).

More evidence for a per meal dose came from a short-term study that found an even pattern of high quality protein at each meal (30 grams per meal; 1.2 g/kg for the day) as opposed to a skewed pattern (10 grams at breakfast, 15 g lunch and 65 g at dinner; 1.2 g/kg for the day) may be best for maximally stimulating muscle building in young adults (1).

Despite the evidence in favor of an even distribution of protein intake throughout the day, a short-term study in older, resistance trained adults given 2x the RDA – 0.68 grams of protein per lb. bodyweight (1.5 grams per kg) per day in an uneven or even pattern (see chart at the end of this article) or the RDA of 0.36 grams of protein per lb. bodyweight (0.8 grams per kg) per day again in an uneven or even pattern found the pattern of intake didn’t matter. Consuming 2x the RDA, regardless of whether it was consumed in an uneven or even pattern, led to a significantly greater increase in muscle protein synthesis compared to consuming 1x the RDA. The pattern of protein intake didn’t matter, possibly due to age-related decline in muscle response to protein intake,  greater total daily protein intake or some other factor (6).

What Happens to Excess Protein Intake?

There is no long-term storage site for amino acids, the building blocks of protein. After eating a thick juicy steak, creamy bowl of split pea soup or sizzling soy fajitas, your body digests the protein and absorbs the amino acids, using them to build new structures, including muscle. However, the amount of protein we can digest and absorb greatly exceeds the we can use to build muscle tissue (8).

After you eat protein, your gut takes some of the amino acids (based on research in animals, the gut takes 40-50% of the available amino acids from dietary protein) and uses it for energy and local protein synthesis. Your liver also takes some amino acids and uses them to make liver and liver-derived blood proteins (9).

When excess protein is consumed, more than the body needs at that point in time, the rest is used for energy or  converted to body fat. The nitrogen (from amino acids) is combined with other compounds to form urea, a harmless waste product, which is processed by the kidneys and excreted in the urine.

What Influences Protein Requirements?

Though 90 grams in one sitting may be more than necessary for muscle, science has yet to figure out the exact threshold beyond which there is no benefit for muscle. This is a complicated question as there are many factors that influence a person’s daily protein needs as well as how much protein a person may need at each meal. These include but are not limited to: age, training status, total daily calorie intake (if dieting total protein needs are higher), overall amount of protein consumed each day; the type (anti-nutrients?), quality and leucine (or EAA) content of the protein consumed at each meal, other nutrients consumed at meal time, training program, lean body mass, health status and goals.

How Much Protein Do You Need at Each Meal?

Given the research to date, does a per meal does matter?

If you are dieting, yes.

If you don’t get at least 0.55 grams protein per lb. body weight (1.2 grams per kg), yes.

If you eat plenty of protein every day and a decent amount at regular meals throughout the day, it might not matter that much, or at all.

For now, stick to the general guideline of at least 25 grams per meal (the amount of an average female’s palm worth of chicken, turkey, red meat, fish). You may need more, per meal, to maximize muscle growth and repair  if:

• You are older (relative term since we don’t know exactly what age qualifies as “older). Aim for 1.0 – 1.5 grams of protein per day (7) and regular meals with a good amount of protein per meal. If you have chronic kidney disease, follow the advice of your RD and MD.
• You eat primarily vegetarian proteins.

Many factors influence a person’s nutrition needs. If you want to maintain or gain muscle mass and strength, concentrate on your total daily protein intake (at least 0.55 grams of protein per lb. of bodyweight; 1.2 grams per kg) followed by how much you consume at each meal. There is no one-size-fits-all ideal protein intake per meal and the body doesn’t just “waste” protein that isn’t used for muscle building. For now, research suggests 25 to 45 grams per meal is a good general guideline. More may be better for muscle. Less may be necessary if you have chronic kidney disease.

Table: Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults (select data and average leucine intake calculated)

Amount	Pattern	Meal	Protein (grams)	Protein as a % of total calories	Average leucine intake per meal (calculated)
1x RDA	Uneven	Breakfast	11.1	8	0.89
		Lunch	14.9	8	0.89
		Dinner	47.8	12	3.56
		Total	73.7	10	4.45
	Even	Breakfast	22.3	15	1.63
		Lunch	21.5	9	1.63
		Dinner	22.0	9	0.81
		Total	65.8	11	4.07
2x RDA	Uneven	Breakfast	18.1	15	0.80
		Lunch	24.3	12	1.60
		Dinner	78.4	22	4.79
		Total	120.8	19	7.99
	Even	Breakfast	38.0	25	2.98
		Lunch	36.5	17	2.98
		Dinner	37.9	18	2.23
		Total	112.4	19	8.2

References

1 Mamerow MM, Mettler JA, English KL, Casperson SL, Arentson-Lantz E, Sheffield-Moore M, Layman DK, Paddon-Jones D. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr. 2014 Jun;144(6):876-80.

2 Moore DR, Churchward-Venne TA, Witard O, Breen L, Burd NA, Tipton KD, Phillips SM. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. J Gerontol A Biol Sci Med Sci 2015;70(1):57-62.

3 Loenneke JP, Loprinzi PD, Murphy CH, Phillips SM et al. Per meal dose and frequency of protein consumption is associated with lean mass and muscle performance. Clin Nutr 2016 Apr 7.

4 Symons TB, Sheffield-Moore M, Wolfe RR, Paddon-Jones D. A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects.J Am Diet Assoc 2009;109(9):1582-6.

5 Deutz NE, Wolfe RR. Is there a maximal anabolic response to protein intake with a meal? Clin Nutr 2013;32(2):309-313.

6 Kim IY, Schutzler S, Schrader A, et al. Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults. Am J Physiol Endocrinol Metab 2015;308(1):E21-8.

7 Paddon-Jones D, Campbell WW, Jacques PF, Kritchevsky SB1, Moore LL, Rodriguez NR, van Loon LJ. Protein and healthy aging. Am J Clin Nutr 2015 Apr 29.

8 Stokes T, Hector AJ, Morton RW, McGlory C, Phillips SM. Recent perspectives regarding the role of dietary protein for the promotion of muscle hypertrophy with resistance training. Nutrients 2018;10(2): 180.

9 Macnaughton LS, Wardle SL, Witard OC, McGlory C, Hamilton DL, Jeromson S, Lawrence CE, Wallis GA, Tipton KD. The response of muscle protein synthesis following whole‐body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiol Rep 2016;4(15): e12893.