In this article we break-down the protein requirements for female strength athletes and how to calculate them. However, before jumping into the details, we first need to cover some background information.
So what is a protein? A protein is actually a chain of amino acids, both essential and nonessential, linked together in the body by peptide bonds. A nonessential amino acid is simply an amino acid that the body can synthesize. Essential amino acids are the amino acids the body cannot make, and therefore must be incorporated through diet. Proteins go through physical conformation changes to create a 4D structure in their final form. This structure determines what their function or role in the body will be.
Proteins are not limited to just muscle. Every single biological reaction that occurs in the body requires a protein of some kind. Whether that be an enzyme (a protein that allows for biochemical reactions to occur) or a structural protein, protein is not just limited to muscle and muscle growth. At any given moment, the body likely has a billion reactions occurring, and all of those reactions require a protein of some kind.
Unlike the other macronutrients, carbohydrates and fats, protein is not a primary energy source for the body. Protein in its enzymatic form, actually uses energy in order to carry out reactions. The body can use protein for energy, but it is not its preferred source. If the body is at a complete lack of carbohydrates and fats, it can utilize protein for energy, but it is certainly not an effective source of energy. The body has certain pathways that it can utilize to generate energy that require the dietary carbohydrates and fats, but not protein.
Protein Requirements for the Strength Athlete
Current research shows that strength athletes require about 1.5 – 2.4 g/kg body weight per day of protein (1–3). One study investigated the correlation between protein intake and fat loss. The RDA (Recommended Dietary Allowance), which is 0.8g/kg a day for protein, just for the average person, is the minimum amount needed, not necessarily the optimal amount, but the minimum amount needed to meet the nutritional requirements of the average adult. Researchers investigated the amount of fat loss at 1x RDA, 2x RDA (1.5 g/kg), and then 3x RDA (2.4 g/kg). They found that the 2x RDA group and the 3x RDA group had more fat mass loss over a period of time than the 1x RDA group; however, the 2x RDA group lost ~6% more fat mass than the 3x RDA group, which is fascinating (3).
So why does that happen?
We speculate that when you are consuming more protein than what your body needs, you’re taking away from those other sources of food that give you energy, like carbohydrates and fat. Potentially the individuals that were in the 3x RDA group weren’t getting enough energy from their food and maybe, because they were all going through a resistance training program, weren’t able to train as hard.
We know carbohydrates are what the body wants to use for energy. It’s the easiest source of energy for your body. It will also use fat for energy, if it has to, and then protein as a last resort. If you’re eating double the amount of protein than what your body needs, that’s a significant amount of carbohydrates and fats (i.e. energy) you’re missing out on. The research shows that if you ingest that extra protein, it’s going to be turned into free amino acids circulating in your blood. Eventually, unused free amino acids are excreted from the body.
In terms of endurance athletes, one study in particular looked at time trial cycling events and protein consumption. The researchers compared 3 g/kg (high) to 1.5 g/kg (moderate) protein in cyclists 4,5. They found that the higher protein consumption group performed worse at a time trial after 4 weeks on the high-protein intake than the moderate group. Since the caloric intake had to remain constant between the two groups, carbohydrate consumption was reduced in the high-protein group to compensate for the additional protein. This means that the moderate-protein group had more readily available energy at their disposal.
Higher protein might make sense if we think about it in terms of balancing muscle protein synthesis (MPS) and muscle protein degradation (i.e. anabolism and catabolism, respectively). The body is always on the move. All the proteins in the body are being built (MPS), used, or broken down to their amino acid components (degradation) and recycled to build new proteins. It’s a cycle, and as long as there is an adequate amount of free amino acids for the body to use to build new proteins (anabolism), the breaking down of other proteins (catabolism) is minimal. In theory, if we give the body more protein than it needs (more protein than optimal requirements), it won’t resort to breaking down other proteins (i.e. muscle) in the body for their amino acid components. However, if the protein takes away from the carbohydrate and fat consumption, our bodies won’t have the energy to carry out the functions of these proteins, and it won’t have the energy to perform optimally during training.
Meal Timing & Protein Intake
Over the years the Strength and Fitness industry has been introduced to new and different ways of eating, each with their own promises and caveats. These methods include intermittent fasting and the body building diet, which consists of 6-10 meals a day! Each way of eating claimed their method was the most optimal in terms of performance, aesthetics and metabolic advantages; however, most of these methods did not actually have scientific backing, until now.
There was a study that looked at protein consumption, the number of meals consumed on a day-to-day basis, and muscle protein synthesis (MPS). Keeping protein amount constant, they investigated how various numbers of feedings during a single day stimulated MPS (6). Multiple groups were assigned different meal frequencies (i.e. one, two, three, four and up to eight meals a day). The researchers divided the total daily protein by the number of meals assigned to each group(if there was only one feeding, all of the daily protein was eaten at that meal), so that way each group received the same total amount of protein, but took in different amounts throughout the day. They discovered that the people who were given the smaller amounts of protein consistently throughout the day (6+ feedings) and the people who had huge amounts of protein a couple times a day (1 – 2 feedings per day) had less stimulation of MPS than people who had 3 – 4 feedings per day 3. The 3 – 4 feedings consisted of about 0.3 g/kg of total body weight per meal of protein. If you do the math, that’s going put total protein right around 1.5 g/kg of body weight. Therefore, to optimally stimulate MPS throughout the day, the minimum protein requirement is 1.5g/kg per day with 0.3g/kg of protein at each meal.
Protein Quality
Protein quality refers to the level of essential amino acids in the food. So the higher numbers, (the higher levels of essential amino acids) means that it’s a higher quality protein. So a lower quality protein means it has lower levels of essential amino acids. Animal sources naturally have the highest amounts of essential amino acids. They’re higher than plant sources of protein. The branched chain amino acids (BCAAs), leucine, isoleucine, and valine, are particularly important for driving MPS after resistance training. Below we have included a chart that clearly shows the best quality protein supplement sources for both animal and plant-based athletes.
Protein, Energy, & Training
Here at Female Strength Academy, we want to help take this research and make it applicable for you, the female strength athlete. In terms of protein requirements, here is what we’ve found:
- Most people over-consume protein.
- Ultra high-protein diets are not optimal for fat-loss.
- Ultra high-protein diets take away from other macronutrients, such as carbohydrates and fats, that can be used for energy.
- Protein quality matters.
As a student and a strength athlete, you are going to have to find what is right for you. As we showed at the beginning of this article, the protein requirement for each person needs in a day falls within a range (1.5 – 2.4 g/kg). While most people would likely benefit from the lower end of the range (1.5 – 1.8 g/kg), some individuals would be more comfortable at the higher end of the range. Just keep in mind that as an athlete, it is not about how you look, but how you perform. If you set protein way above the range (close to 1 g/lb of body weight), then you’re doing yourself a disservice in terms of athletic performance. Make your food work for you. Besides general health and mental well-being, keeping carbohydrate and fat macros higher will allow for better performance in training and in competition.
If you want to learn what macros are right for you and how to better use your carbs and fats for training, check out our Eat for Strength course. In it, we teach you how to optimize nutrition and your mental state to achieve higher athletic performance.
Want more? Check out EPISODE 78 of Empowered by Iron: Protein, how much do you really need?
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References:
- Campbell B, Kreider RB, Ziegenfuss T, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2007;4(1):8. doi:10.1186/1550-2783-4-8
- Peos J, Norton L, Helms E, et al. Intermittent Dieting: Theoretical Considerations for the Athlete. Sports. 2019;7(1):22. doi:10.3390/sports7010022
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14(1):20. doi:10.1186/s12970-017-0177-8
- Macdermid PW, Stannard SR. A Whey-Supplemented, High-Protein Diet versus a High-Carbohydrate Diet: Effects on Endurance Cycling Performance. Int J Sport Nutr Exerc Metab. 2006;16(1):65-77. doi:10.1123/ijsnem.16.1.65
- Witard OC, Jackman SR, Kies AK, Jeukendrup AE, Tipton KD. Effect of increased dietary protein on tolerance to intensified training. Med Sci Sports Exerc. 2011;43(4):598-607. doi:10.1249/MSS.0b013e3181f684c9
- Churchward-Venne TA, Murphy CH, Longland TM, Phillips SM. Role of protein and amino acids in promoting lean mass accretion with resistance exercise and attenuating lean mass loss during energy deficit in humans. Amino Acids. 2013;45(2):231-240. doi:10.1007/s00726-013-1506-0
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