Why do we need protein in our diet?
Protein is more than a trendy 'buzzword' that seems to be appearing on an ever-growing amount of food products - this mighty macronutrient offers many health benefits. Team Grenade Ambassador and Nutritionist Vinny Russo takes a look at why protein is important for your fitness related goals.
Protein is a Greek word that literally means “of prime importance.” It's the foundation to every human body, required by every cell in the body, and is an important building block for muscles, bones, blood, and cartilage. Just to give you an idea of how important protein is, here are a few functions that this macronutrient does within the human body.
(1) Protein makes up enzymes which help catalyse reactions in the body
(2) Helps guide most nutrients to the right places to be used in the body
(3) Acts as a “buffer” by making an alkaline environment less alkaline (same with acidity)
(4) Protein engages in the regulation of fluid balance
(5) Helps produce hormones
(6) Provides energy
(7) Needed to build tissue
Protein is made up of Amino Acids which are the building blocks to all muscle growth. Without protein, it would be impossible for your body to build, repair and maintain muscle tissue. Having a sufficient amount of protein will put you in a positive nitrogen balance, which is ideal for fitness goals. A positive nitrogen balance then equates to an anabolic state! Basically, in a nut shell, if you’re skipping-out on the protein, you will continue to live on a physical plateau.
I feel protein is of prime importance for your fitness related goals for two main reasons. The first reason deals with your gains! Yes! The hard work you put in at the gym when you’re throwing weights around needs to be supported by sufficient protein intake. How much an individual needs is going to vary person to person so, to give an exact number right now is not plausible. From what we know, protein is comprised of 20 amino acids with a few of them to be able to determine how much protein you will actually need. This research is being conducted currently, so hopefully in the near future we will be able to have an answer. As of now, there is no set number in terms of grams per individual, but there are recommendations.
The reason you want to make sure you are consuming enough protein, is to increase the amount of muscle protein synthesis (MPS) in your body. We want to increase this to the point where it exceeds the amount of muscle protein breakdown (MPB). If your MPS is less than or equal to MPB, you cannot build muscle and are therefore risking muscle loss.
So how do we make sure that MPS is greater than MPB? We need to focus on consumption of protein throughout the entire day. The MPS will peak after consuming protein (only if enough of the amino acid leucine is ingested from the meal) and will eventually drop off. Leucine is important here as it is considered the “trigger” to the MPS process. Studies have shown (credit to Stu Phillips) that about 2.5 grams of leucine is needed to elicit muscle protein synthesis in adults. Although leucine seems to take victory being the most important/sought after amino acid, all of the essential amino acids are still needed as the foundation for building new muscle proteins. We want to ensure we get the full spectrum of aminos, not just concentrate on consuming leucine.
From what you just read you will most likely come to the conclusion that the end goal is to keep MPS elevated at all times. Just eat enough protein in the day to keep this elevated right? Not so fast! The problem is that the process of MPS is very energy demanding! So no matter how much protein you eat in one sitting, only about 15-30g will be used for the process of MPS and the rest of the protein will be used for other services needed within the body. Once initiated, the process of MPS will run until ATP (our chemical energy currency) is depleted and taper off. This means your body does not keep MPS elevated 3 x longer if you ingest 3 x the amount needed for the process. It uses what it needs and the rest of the protein will be used elsewhere. Once MPS resets back to normal, this is when we are able to, and should want to, raise MPS again.
The way to do this is to spread your protein portions out over the entirety of the day since research has shown the MPS process takes about 2-3 hours before normalising. In a nut shell, taking in protein after it peaks, but before it normalizes will not contribute to more protein synthesis. This is where protein portions being spread out over a number of meals has its advantages over 1 to 2 big intakes of protein at one time, in terms of maximising MPS. That last part is an important distinction! We will have more spikes of MPS with more frequent feedings (3-5) compared to 1 to 2.
The “protein turnover” you experience is governed by your amount of protein intake. For this reason alone we would want to keep overall protein intake on the higher end of the spectrum. By “protein turnover” what I am referring to is muscle tissue being built up and broken down. So to give a brief explanation, when you eat a meal containing protein, given it is enough, you will stimulate MPS and release insulin which will suppress MPB. This means you will have a greater rate of protein synthesis compared to protein breakdown (a very good thing). But, as the day goes on and you go on with your daily life, MPB is given the chance to surpass the MPS until we consume protein again.
On average, we have this see-saw effect and the amount of increased MPS usually ending up equal to the amount of increased MPB, thus leaving us stagnant with a net MPS of O. The end goal is to spend more time with a high rate of MPS compared to MPB to result in the addition of (if in a caloric surplus), or maintenance of muscle tissue! I must note that protein turnover has more of a correlation to hypertrophy (building of muscle tissue) than does the rate of MPS. Keep in mind that the rate of MPS is a foundational element of protein turnover.
The 2nd reason protein is of prime importance is due to its ability to facilitate fat loss! Does protein do this directly? Yes and no, so let me explain a few ways protein takes part in this process.
Exercise in general is used as a way to burn body fat. Whether you are into resistance training or long distance running, it doesn’t matter. A trained body needs protein! Many studies have shown that in trained individuals, and in individuals going through a dieting phase, a higher protein diet was superior. It has been shown that higher protein diets led to greater muscle retention in a caloric deficit (Wycherley 2012) and increased fat loss (Laymen 2003). In a diet phase, the diet that consisted of higher protein, led to more maintenance of lean body mass which allowed the individual to lose more weight from their body fat. During a dieting phase (in an energy deficit), we know that MPS becomes compromised. We talked earlier how important MPS is, so we understand that we don’t want, nor need this process to be hindered. One important way to counter this concern would be to increase your overall protein intake!
Another way protein can facilitate fat loss is with higher levels of satiety. Why is satiety so important? Well, when one is in a caloric deficit (the only way to lose body fat), your leptin levels decrease, and ghrelin will increase causing you to become hungry and want to increase your caloric intake. Usually this effect will make people quit on their diet plans, or decrease their adherence to it. Protein being very satiating, helps to alleviate the experience of hunger which will increase the adherence to the plan and actually make the individual want to consume, and thus end up consuming fewer calories overall.
Finally, I want you to understand that in order for your body to breakdown protein, and to run the process of MPS, it all requires energy! Protein requires more energy to absorb, digest, and utilize than the other macronutrient. So, when comparing equal amounts of calories consumed, protein vs. carbs vs. fats, there is less energy being consumed with protein overall due to the amount of energy needed to break it down. The thermic effect of protein is high leaving us with only about an 80% absorption of total protein from the given food. As an example, if 80% of protein calories are absorbed (20% burned away in trying to break it down) then from 100 calories (of protein) ingested, only 80 calories would be available. Now, looking at the MPS side of things, we already mentioned how energy-expensive it is to run. So if you stimulate protein synthesis with a higher protein intake, then your energy expenditure will be increased as well. This becomes a recipe for less total calories as a net total.
All of these factors together help show that a higher protein intake, or at minimum a sufficient protein intake, is important for fat loss, muscle retention, muscle building, and optimal body composition. Protein yields so many benefits that seem to be masked by its effects on muscle tissue, but this article was written to highlight the benefits it has with fitness related goals. Lastly, in case you are worried about too much protein damaging your body, a study conducted by Antonio et al. in 2016 shows that there were no negative side effects from a high protein diet in healthy, resistance-trained individuals.