Protein and Athletes
Protein is all the rage these days. Protein shakes, bars, and other supplements are likely blowing up on your social media and/or at the supermarket. You might know a person who has a protein shaker bottle with them at all times. Or maybe you know someone from high school who is now pushing protein supplements on Facebook, repping for some random (sketchy) nutrition supplement company. And how about the explosion of options in the yogurt isle at the grocery store? A couple of flavors of Dannon or Yoplait at the store has ballooned into full blown Yogurtland, with a million brands and flavors, especially of the new high-protein king, Greek yogurt.
So do we really need tons of protein? The Recommended Dietary Allowance (RDA) for adults is set at .8 g/kg protein per day. A 140 lb (~64 kg) person would need about 51 g protein and a 200 lb (~91 kg) person would need about 73 g protein per day according to the RDA for protein. It is important though to understand that this recommended .8 g/kg was established as the minimal amount of protein that the average person needs to achieve a protein balance and avoid deficiency. In addition, it has been suggested that the nitrogen balance method used to establish the RDA is not the most accurate. A newer, perhaps more reliable means to finding protein needs, called the indicator amino acid oxidation method (IAAO), determined that protein needs for the average person are actually about 40% higher than the RDA, recommending people need about 1.2 g/kg protein per day. Another guideline for protein intake established by the Institute of Medicine is a dietary protein intake range of 10-35% of total calories.
For athletes, protein requirements are in fact higher for a few reasons. To start, the RDA, regardless of the method used, is meant to meet minimal protein requirements. This is very different from establishing the optimum amount of protein needed to support an athlete’s performance or help them achieve body goals. Ask any athlete and I am sure they will say that optimal is more favorable than minimal when it comes to the results of their nutrition plan.
Physical activity means using muscles, and the more muscles are used and challenged, the more protein they generally need. Protein helps muscles repair and rebuild from the most recent physically demanding session to prepare for the next. Because athletes by nature are more active than the average office worker, they require more protein to support their muscles. The amount needed can vary considerably though depending on sport and an athlete’s objectives for things like performance, body composition, and weight loss.
While it has yet to be determined if there is truly an optimum protein intake amount for athletes, research has provided several ranges to work around when determining what is right for a specific athlete. An appropriate range of protein intake for athletes may be 1.2-2.0 g/kg on a daily basis. This is higher than the RDA and is thought to provide enough protein to support muscle recovery and adaptation around physical activity. Less protein will be needed when putting less strain on muscles. Consuming protein closer to 2.0 g/kg makes sense for athletes performing more intensive activities like weight lifting, or with an increase in training volume.
Protein consumption manipulation is an effective nutritional “tool” to use for multiple objectives. For an athlete, or anyone really, who wants to lose fat mass while maintaining or even increasing muscle at the same time, more protein is key. Decreased calorie intake in combination with increased protein, and especially with regular physical activity, can help the body hold on to muscle mass while losing fat. So, how much protein? Research has determined that about 1.8-2.7 g/kg protein per day is effective in maintaining muscle mass while losing fat mass when practiced together with a decrease in calories and performance of resistance training. A similar range of 1.6-2.5 g/kg protein per day is recommended for athletes experiencing an injury who want to attenuate muscle losses during the period of decreased physical activity.
In addition to overall daily intake guidelines, studies have illuminated how timed protein intake can benefit athletes in terms of recovery and muscular adaptation after exercise. Recovery nutrition seems to be the most widely studied area of protein timing. The current recommendation is to consume ~.25-.3 g/kg high quality protein (like whey or soy) in combination with about .8 g/kg carbohydrates within 30-60 minutes of activity to maximally stimulate protein synthesis and refuel muscle glycogen stores. Muscle recovery doesn’t just stop while you sleep, so giving your body some protein and carbs before bed can continue and enhance recovery and rebuilding of muscle. Research has shown that ingestion of about 28 g protein and 15 g carbs before bedtime results in greater muscle growth with resistance training versus no supplementation before bed.
Okay, so we have established general protein intake guidelines for the day, and also for recovery, but how should an athlete have their protein throughout their day to get the most out of their nutrition? Well if the athlete is looking to maximally stimulate muscle protein synthesis, or grow muscle, as many athletes are trying to do, .25-.4 g/kg or about 20-40 g protein per meal is appropriate. A physically smaller athlete will need less protein than a larger athlete will, at least in regard to reaching the threshold of peak muscle building.
Here is an example to see what this would look like in real life: A 165 lb (75 kg) athlete wants to hit 1.8 g/kg protein per day, or 135 g protein. This could be done with 3 meals with 30 g protein and 2 snacks, one with 20g protein and one with 25 g protein throughout the day. One thing to consider is where all this protein is coming from. While there are tons of foods that offer us protein, not all proteins are created equally. Protein quality is a factor that athletes should think about when choosing foods for meals and snacks to meet protein needs. A high quality protein is one that can be fully absorbed and digested, and that provides the body with the essential amino acids (EAAs). EAAs are proteins that we must get through our diet because our bodies cannot make them.
There are nine total EAAs. Animal proteins like meat, fish, poultry, eggs, and dairy are considered high quality proteins and contain all 9 EAAs. Plant sources of protein like nuts, beans, grains, and seeds each contain some of the essential amino acids, but not all, and so are not considered high quality. The exception to this is soy protein, considered just about as high quality as animal protein sources. Even though plant proteins may not provide us with as much protein as animal sources, a mix of protein sources is definitely recommended as plants have so many other great benefits to offer like fiber, healthy fats, and phytochemicals along with their protein. Athletes who stick to a vegetarian or vegan diet should be getting a variety of plant proteins in their diet to ensure that they are consuming all the EAAs.
Another consideration for a meal or diet that has protein coming from largely plant sources is that because the bioavailability of plant protein is generally low, it may be wise to consume a greater quantity of plant protein at a time to reach protein needs. For example, if an athlete desires to get 25 g protein from a meal where the protein source is beans, they should consume a serving size providing greater than 25 g protein according to the nutrition facts label, as the lower bioavailability of this protein means that the body is not able to absorb or utilize all the protein in this food.
So, it seems clear that a diet higher in protein makes sense for athletes, but is there such thing as too much? There is actually no tolerable upper intake level (UL) determined for protein intake. The UL establishes the amount of a micro- or macronutrient that can be consumed without causing harm to the average person. When looking at potential upper limits for intake of individual amino acids found in foods, the real life translation comes to around 350-475 g protein per day. That is a ton of protein that is hard to achieve even in the case of a large strength athlete consuming up to 3.2 g/kg. Research has found that at least in the short term, very high protein diets are not deleterious to health. One study found that intakes of 4.4 g/kg protein over 8 weeks did not result in any changes to weight or body composition compared to a 1.8 g/kg protein diet within resistance-trained people.
High protein intake often brings up concerns about renal function and bone health. If you consume more protein than your body can utilize (go beyond nitrogen balance), the kidneys must filter out the excess protein, theoretically putting more strain on the kidneys. However, in healthy people kidneys are able to increase their efficiency of protein removal with greater protein intake. For people with renal issues, lower protein intake ranges are advised. Increased calcium excretion can result from increased protein intake and raises the question if a high protein diet can increase risk for bone loss or fractures. A meta-analysis found no negative effects of protein on bone health, and if anything there is actually a small positive effect.
hile a very high protein diet may not be harmful to the body from what we can tell so far, more is not necessarily better. The body is only able to use so much protein at a time and excess will just be excreted. So you can drink that shake with 80 g of protein, but that basically results in you literally flushing money down the toilet. In addition, a diet that has a ton of protein is likely not leaving enough room for the other macronutrients, fat and carbohydrates. Sticking to a protein intake within the 1.2-2 g/kg range is the most current and evidenced-based guideline for athletes to follow. We also have learned from much research about how using different protein forms and strategically timing protein intake can help athletes build lean muscle mass and work towards improving body composition and performance. Hopefully this little review helps you make better, more informed decisions about how, why, and when you get your protein. It can be overwhelming though, so if you have questions, ask an RD!