Protein plays a key role in many bodily functions
Nutritional trends come and go, but one thing seems to remain the same: appreciation of protein as the king of the macronutrients. One year carbohydrates are the enemy, the next it’s fat’s turn, but we never seem to demonize protein – for a good reason, as it plays a significant role in many bodily functions, and as a building block for muscle. It should be emphasized though that no macronutrient is “bad”, and all of them are important for health and performance – and all of them in excess may contribute to poor health and weight gain. However, out of all of the three macros, protein is the one most often under-consumed especially by females, and particularly females in sport, whose needs are not only increased due to their activity levels, but also simply due to being a woman.
Protein consists of amino acids, and there are 20 of them that make up the proteins in the human body. Nine amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) are not synthesized by humans and are therefore dietarily essential and called the ‘essential amino acids’. Protein from nutrition helps in maintaining the balance between muscle breakdown (catabolism) and synthesis (anabolism), and helps with weight loss, muscle hypertrophy and strength gains; recovery, maintaining a healthy immune system, sleep, digestion, and reproductive health.
Women’s macronutrient needs change during the different phases of the menstrual cycle and should be taken into consideration in the nutritional strategies. Protein needs increase during the luteal phase when estrogen and progesterone levels increase. During this time of the month, protein oxidation at rest increases, as progesterone has a catabolic effect in the muscle. Estrogen, on the other hand, inhibits anabolic signals in the muscle, and as a result, protein breakdown and use for energy during exercise increases, and it becomes more difficult to build and maintain muscle (a double whammy!). These processes also slow down recovery, and it may feel a lot more difficult to hit your targets in workouts.
Fuel your female physique
Women’s metabolism differs greatly from that of men’s. Firstly, men build muscle and lose fat easier than us women. Secondly, men’s post-exercise metabolism remains elevated way longer than women’s (I’m talking about 21 h vs. 3 h!). For women, what we eat before and after exercise seems to matter even more and adequate protein intake is important for female athletes to maintain the balance between muscle breakdown and synthesis.
Research suggests that consuming 15-20 g of protein before hard exercise supports better muscle retention and stronger performance. Pre-exercise protein has been found to increase muscle anabolism more compared to post-exercise protein. However, consuming protein both before and after exercise is important especially in the mid-luteal phase, when the hormone levels are at their highest and protein oxidation more rapid.
Women recover faster with 25-30 g of protein within 30min of hard workouts (both endurance and strength). Waiting for longer to refuel will put the body in a catabolic state that will negatively impact recovery, metabolism and increase fat storing as it signals the body that it might be in a state of famine. The 30min refueling window is also important as delaying the post-exercise nutrition will decrease insulin sensitivity, which results in lower glycogen storage. Inadequate glycogen restoration will negatively impact future performance. It is recommended to consume carbohydrates along with your protein, as they together improve glycogen storage rates and muscle recovery and repair, and has also been found to reduce inflammation and boost immunity. Remember to also consume enough protein throughout the day (and not just before and after the workouts). Research shows that consuming 20-30 g of protein in frequent feedings throughout the day improves muscle hypertrophy and performance more than larger boluses less frequently, or smaller portions more frequently.
For those attempting weight loss, consuming protein pre-exercise may increase resting energy expenditure and decrease respiratory exchange ratio (i.e. the ratio of fat vs. carbohydrate utilization for energy; lower number indicates more fat is being used). Eating more protein burns more calories as its digestion requires more energy.
Meeting the targets
Current protein recommendations for the general population are 1,1–1,3 g/kg for 18–64-year-olds and 1,2–1,4 g/kg for 65-year-olds and older per day regardless of sex. It is often believed that women need less protein than men due to their lower muscle mass, but that is not the case. Of course, protein needs are highly influenced by body size and lean body mass, but one key contributor is activity levels. As demonstrated by a study  of female cyclists and triathletes, active women need more protein, and the participants’ average protein needs (1,63 g/kg/day) were similar to their male counterparts. It should also be emphasized that the study was conducted during the mid-follicular phase, when the protein oxidation is not as high as during the mid-luteal phase. Therefore, the actual needs are likely even higher during the luteal phase.
As mentioned before, there are nine essential amino acids that we need to get from our nutrition. Complete protein sources contain all nine essential amino acids in the “same package”. While protein from animal sources contains all the nine essential amino acids, it is also possible to get them all from plant protein sources by combining different ingredients. For example, pea protein combined with oat will give you all the nine. Female athletes can meet their daily protein needs by consuming a variety of protein-rich snacks and meals throughout the day.
Suggestions for meeting daily protein needs:
Throughout the day: 20-30 g of protein in snacks and meals
E.g. SIS Protein Bar; Greek yogurt with granola and fruit; chicken breast; stir fry with tofu.
- Bonke A, Sieuwerts S, Petersen IL. (2020) Amino acid composition of novel plant drinks from oat, lentil and pea. Foods. 2020 Apr 3;9(4):429.
- Houltham, S.D. and Rowlands, D.S. (2014). A snapshot of nitrogen balance in endurance-trained women. Applied Physiology, Nutrition, and Metabolism. 39(2): 219-225. https://doi.org/10.1139/apnm-2013-0182
- Ruokavirasto. Proteiinin tarve, saantisuositukset ja lähteet. 8.6.2023. https://www.ruokavirasto.fi/elintarvikkeet/terveytta-edistava-ruokavalio/ravintoaineet/proteiini/
- Sims, S.T. (2016). ROAR - How to match your food and fitness to your female athlete physiology for optimum performance, great health, and a strong, lean body for life. Rodale.
- Sims, S.T. (2022, July 22) Why women need to prioritize protein. Dr. Stacy Sims. https://www.drstacysims.com/blog/Why-Women-Need-to-Prioritize-Protein
- Wohlgemuth, K.J., Arieta, L.R., Brewer, G.J. et al. (2021). Sex differences and considerations for female specific nutritional strategies: a narrative review. J Int Soc Sports Nutr 18(27).
Minttu Hukka is a professional triathlete and an exercise physiologist, with experience in wearable technology research. Minttu currently works at Huawei Technologies Finland as a human performance laboratory specialist, while pursuing her professional triathlon career.
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