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What You Should Know About Protein and Muscle Mass

By Tom Nikkola, CSCS, CISSN, Pn1

The debate over how much carbohydrate and fat people should eat often overshadows the importance of protein intake. This is unfortunate, since protein plays such a hugely important role in health, fitness, and performance.

One of protein’s most important roles is in the maintenance of lean body mass, or muscle. There’s no doubt that muscle improves overall function and performance, and helps improve body composition. Even more important, muscle mass is a major factor in long-term health and quality of life.

Protein is key to maintaining lean body mass. But how much is really necessary?

If you’re young, you might be surprised to find out that you don’t need as much as you may think. If you’re in the second half of life, you might also be surprised to find out that you need more than you probably eat.

This article scratches the surface of the value of higher protein intakes and addresses a few common myths. Protein is a meaty topic. It would take far more space than a single blog post to cover the topic, so I’ll cover other aspects of the protein discussion in future articles.

Also, to limit the scope of the discussion, we’re talking specifically about protein and not focusing on the sources other than the difference between animal and plant-based protein, or different animal proteins like conventional vs. grass-fed or wild caught.

What Are We Talking About?

When we talk about protein, we’re generally referring high-quality protein sources, including meat, eggs, fish, poultry, wild game, whey and other dairy proteins.

We can also include a few plant-based sources of protein such as a mix of pea and rice protein powder, or protein from soy. However, we tend to steer people away from soy due to it being highly allergenic, commonly being genetically modified and still controversial surrounding soy’s effects on hormones.

To keep things simple, we’ll talk about intact proteins rather than getting into the details of specific amino acids. I’ll reserve that topic for another time.

Unlike fat and carbohydrate, the human body cannot store extra protein for use at a later time. It must continually be supplied through the diet, in order to make available all the essential amino acids the body needs each day.

That makes daily protein intake pretty important.

Effects of Protein On Lean Mass

Protein consumption does three things related to lean mass.

First, protein breaks down to amino acids. Amino acids are the building blocks for virtually every tissue in the body, including muscle. If you don’t provide enough essential amino acids (EAAs) through your diet, your body won’t have what it needs to maintain health and support the maintenance of bone and muscle tissue.

Certain diseases increase amino acid needs, which is why it’s difficult to maintain muscle when one is sick. Though muscle is not an intended storage space for amino acids, in extreme circumstances, the body will break down its own muscle tissue to supply amino acids to other areas of the body.

Second, protein consumption stimulates protein synthesis. Third, it reduces protein breakdown.

Protein synthesis is the process of assembling amino acids and building tissue, like muscle. At the same time as the body is building up proteins and tissues, it also breaks them down.

When the rate of protein synthesis is greater than protein breakdown, the body produces a net increase in lean body mass. When protein breakdown exceeds synthesis, the body loses lean body mass.

Protein Synthesis and Anabolic Resistance

One of the most fascinating aspects of protein research in recent years has been the finding of “anabolic resistance.” Anabolic resistance is a reduction in the body’s response to protein synthesis stimulus.

To get the same positive effect from protein intake, individuals with anabolic resistance require a greater stimulus – larger amounts of protein or a greater relative intensity of exercise – to get the same effect.[i]

Aging, insulin resistance and obesity can contribute to anabolic resistance.

In healthy, young adults, a meal containing 20-30 grams of quality protein maximally stimulates protein synthesis. Later in life, a much higher amount of protein is required to achieve the same effect.

In healthy young adults, 20 grams of whey protein was sufficient to maximally stimulate protein synthesis following exercise. However, in older adults, 40 grams was required to maximally stimulate protein synthesis..[ii]

Older adults may benefit from more frequent feedings as well. By eating a sufficient level of protein, multiple times each day, they can increase the overall anabolic effect on the body.

Basically, as we age, we need more protein, more often.

It sounds simple enough, but older adults have less of an appetite, so they easily miss meals. When they do eat, they may not eat a protein amount large enough to fully stimulate protein synthesis. Supplementing with extra protein can be especially beneficial for older adults.

As mentioned, obesity and insulin resistance may also lead to anabolic resistance. To maintain lean mass, these individuals may need higher protein intakes than normally as well.

Reducing Protein Breakdown

Caloric restriction or starvation, chronically high cortisol levels, certain drug therapies, reduced activity levels and other nutrient deficiencies can also trigger protein breakdown.

Typical weight loss programs are a common cause of protein breakdown. During weight loss, 20% or more of body weight reduction can come from the loss of lean mass.[iii] Higher protein intakes help to lessen the loss of lean mass and help to preserve normal metabolic rate.[iv],[v]

Just as protein intake stimulates protein synthesis, it can also slow the rate of protein breakdown at rest or during exercise.

Where protein intake seems to reach a cap with 20-40 grams of high-quality protein, rates of protein breakdown continues to be reduced with increasing protein intake.

A 2013 study showed that when individuals consumed 80% of their protein intake for the day in a single meal, the overall anabolic effect from the day’s protein consumption was greater than when they were divided over evenly throughout the day. This flies in the face of the idea that you can only benefit from 20-40 grams of protein in a single sitting.

What the study showed was that there was a more powerful anabolic effect from a very high protein intake in a single meal as opposed to more moderate intakes at multiple times. What it did not show was whether there was benefit to eat multiple very high-protein meals.[vi] Is it possible that multiple, high-protein meals would be even better? Would a much higher protein intake of for the day have an even greater anabolic effect?

A recent study published in the Journal of the International Society of Sports Nutrition used a protein intake of 4.4 g/kg body weight, or 2 g/lb body weight. This is a huge amount of protein, and led to a significant calorie surplus. The comparison group in the study ate just under 2 g/kg of protein.

The high protein group consumed an extra 800 calories per day. Based on the idea that all calories are the same, consuming an extra 800 calories per day should have led to body fat gain. However, the high protein group gained no fat. In fact, the high protein group didn’t gain any weight at all.[vii]

Besides helping to refute the idea that weight management is simply about calories in and calories out, this study also showed that at a certain point, there’s no benefit to additional protein intake for increasing lean body mass.

After around 1 g/lb body weight of protein intake each day, there isn’t a muscle-building benefit to more protein, assuming calorie needs are met and an individual isn’t using anabolic steroids.

Protein Quality

Protein quality is determined by the concentration of essential amino acids. Much of the research on protein intake has been done on dairy proteins, and more specifically on whey protein.

Whey is unique because of its very high concentration of EAAs. In the research, it appears that most protein source have a similar effect, provided enough is consumed to reach a certain threshold of essential amino acids. This would suggest that even plant-based protein sources could provide enough amino acids to stimulate muscle growth. It’s just more challenging to achieve the same volume of essential amino acids found in 20-30 grams of whey, eggs or beef, from eating rice and beans or other plant proteins.

That’s not to say it can’t be done. It just requires much more planning for those who want to optimize lean mass and bone density while following a vegan diet.

How Much Protein?

Protein requirements vary dramatically based on one’s genetics, age, activity level and more. The standard recommendation for protein has been 0.8 g/kg body weight (0.36 g/lb). This amount was determined decades ago and was thought to be an amount sufficient to avoid significant tissue breakdown in healthy individuals.

Although many dietitians still use this low level of protein as a recommendation for clients or patients, in most cases, it is woefully inadequate.

Studies show that protein intakes of between 1.6-2.4 g/kg provide better benefits than lower protein intakes, but there is likely a point at which higher protein intakes no longer provide lean mass improvements.[viii] That doesn’t mean intakes beyond 2.4 g/kg are detrimental, only that they may be unnecessary for maximizing lean body mass.

The timing of meals affects the body’s response to protein as well.

The anabolic effects of protein consumption seem to last for 3-6 hours. If someone eats again before their protein synthesis levels return to normal, the meal will not have the same kind of stimulus as when meals are properly spaced apart. This means for most people, eating 3-4 times per day is sufficient.

Protein requirements tend to go up during fat loss programs, which makes a percentage-based protein requirement difficult. A 150-lb female attempting to lose weight may maintain body fat levels at 2200 calories per day. If she takes in 150 grams of protein per day, that is 27% of her diet. If she follows a fat loss program and ends up consuming 1700 calories per day, her 150 grams of protein become 35% of her diet. Dietitians who limit their clients to protein intakes of 25-30% of calories can create nutrition plans with plans that don’t provide enough protein.

Because protein requirements influence body weight or lean mass so much, it makes more sense to use body weight or lean mass weight as a marker to determine protein needs.

Using body weight, 1.6-2.4 g/kg body weight per day would probably be ideal. To simplify it, aiming for 1 g/lb body weight (or target body weight for overweight individuals) makes sense.

One last point on the protein topic. Inevitably, every time higher protein intakes are discussed, someone asks about the effects on the kidneys.

This is one of those myths that keeps getting repeated. High protein intakes are not good for someone with kidney disease, just like water consumption is detrimental for someone who is drowning. That doesn’t mean protein, or water, are bad for someone who is healthy.

There is no indication that higher protein intakes are bad for the kidneys in healthy individuals.[ix],[x],[xi] Of course, you should never assume you’re healthy without a blood test to confirm it.

To summarize the information above, and make it practical:

  • In young adults, 20-30 grams of an EAA-rich protein like whey, is sufficient to maximally stimulate protein synthesis in a meal. Older adults need larger amounts in a meal for the same benefit.
  • Protein intakes beyond 20-30 grams may not further increase protein synthesis, but they may further reduce protein breakdown compared to lesser amounts.
  • Protein should be consumed at least 3-4 times per day, in amounts that meet or exceed the minimum amount for optimal protein synthesis to get the most anabolic benefit.
  • The ideal amount of protein for the average, healthy, not-exercising at extreme volumes, getting-enough-sleep, middle-aged person is probably somewhere between 1.6-2.4 g/kg. One gram per pound body weight is a reasonable amount to target, provided it’s spread over at least 3-4 relatively even meals.
  • Excess protein is unlikely to contribute to body fat gain, but won’t further increase muscle mass once optimal intakes have been achieved.

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[i] Burd NA, Gorissen SH, van Loon LJ. Anabolic resistance of muscle protein synthesis with aging. Exerc Sport Sci Rev. 2013;41(3):169-173

[ii] Yang Y, Breen L, Burd NA, Hector AJ, Churchward-Venne TA, et al. Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men. Brit J Nut. 2012;108:1780-1788

[iii] Krieger JW, Sitren HS, Daniels MJ, Langkamp-Henken B. Effects of variation in protein and carbohydrate intake on body mass and com- position during energy restriction: a meta-regression. Am J Clin Nutr. 2006;83:260–274.

[iv] Leidy HJ, Carnell NS, Mattes RD, Campbell WW. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obesity 2007;15:421–429.

[v] Tang M, Leidy HJ, Campbell WW. Regional, but not total, body composition changes in overweight an obese adults consuming a higher-protein, energy-restricted diet are gender based. Nutr Res. 2013;33(8)

[vi] Deutz NE, Wolfe RR. Is there a maximal anabolic response to protein intake with a meal? Clin Nutr. 2013;32:309-313

[vii] Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. JISSN. 2014;11:19

[viii] Pasiakos SM, Cao JJ, Margolis LM, Sauter ER, Whigham LD, et al. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. FASEB. 2013;27:3837-3847

[ix] Friedman AN, Ogden LG, Foster GD, Klein S, Miller B. Comparative Effects of Low-Carbohydrate High-Protein Versus Low-Fat Diets on the Kidneys. Clin J Am Soc Nephrol. 2012;7(7):1103-1111

[x] Tirosh A, Fiedler GM, Golan R, Blüher M, Harman-Boehm I, et al. Renal Function Following Three Distinct Weight Loss Dietary Strategies During 2 Years of a Randomized Controlled Trial. Diabetes Care. 2013;36:2225-2232

[xi] Schwingshackl L, Hoffman G. Long-term effects of low-fat diets either low or high in protein on cardiovascular and metabolic risk factors: a systematic review and meta-analysis. Nutr J. 2013;12:48

The posts on this blog are not intended to suggest or recommend the diagnosis, treatment, cure, or prevention of any disease, nor to substitute for medical treatment, nor to be an alternative to medical advice. The use of the suggestions and recommendations on this blog post is at the choice and risk of the reader.
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