Proteins are made up of varying combinations of amino acids --- the building blocks of muscle tissue. There are 20 different amino acids, nine of which are considered essential because your body is unable to create them. The 11 nonessential amino acids can be constructed in the body using materials from other amino acids, so there is no need to specifically include them in your diet. Although people often associate meat and dairy foods as protein foods, protein exists in nearly every food we eat except for fruits, simple sugars and fats.
Although athletes engaged in marathon training or other strenuous endurance training require a slightly higher amount of protein --- between 1.2 and 1.7 g per kilogram of body weight --- moderate exercisers and people engaging in strength-training activities require only about 1 g per kilogram of body weight. That translates into about 0.45 g of protein per pound of body weight, or 70 g of protein for a 155-lb. woman.
Eating meals with a balance of carbohydrates and protein throughout the day will go a long way toward supporting your exercise regimen, but after an especially difficult workout, you may need one or more recovery meals. Recovery meals will consist primarily of carbohydrates, but the addition of protein will speed muscle recovery. Workouts that deplete your glycogen stores --- an hour or more of strenuous weightlifting or endurance work --- should be followed by several snacks of approximately 0.5 g of carbohydrate per pound of body weight along with 0.12 to 0.17 g of protein per pound of body weight. That means that a 155-lb. woman would need roughly 77 g of carbohydrate and 23 g of protein for each recovery snack, a total of 400 calories each time. Milder workouts may only require one recovery snack, but very strenuous exercise should be followed by a snack about 15 minutes after exercise, another about 30 minutes later and a third 30 minutes after that. The average exerciser looking to tone up and lose fat will not need the extra 1,200 calories of three recovery snacks --- only those in serious training.
Don't Overdo It
You should avoid excesses of protein. As "Nutrition & Metabolism" observed in a 2005 review of the literature regarding dietary protein and kidney function, chronic excesses of protein in the diet are positively correlated with increased incidence of kidney disease as well as accelerated progression of kidney disease. There is also a higher risk of osteoporosis related to high protein consumption which, as a woman, you are already at an increased risk of developing. High-protein loads result in higher calcium absorption in your intestines, ultimately resulting in calcium being leeched away from your bones.
Vegetable vs. Animal
According to a study published in "The American Journal of Clinical Nutrition" in 2001, there is a correlation between a diet with a high ratio of protein from animal sources and an increase in osteoporosis and hip and neck fractures. Although the research was not conclusive as to a causal relationship between animal protein intake and reduced bone density, your diet will likely benefit from an increase in vegetable sources of protein since they tend to be lower in total fat and saturated fat and are completely cholesterol free --- beneficial to both your heart health and body weight maintenance efforts.
- "Nancy Clark's Sports Nutrition Guidebook"; Nancy Clark; 2008
- "Nutrition & Metabolism"; Dietary Protein Intake and Renal Function; William F. Martin, et al.; September 2005
- "American Society for Nutritional Services"; Excess Dietary Protein Can Adversely Affect Bone; Urial S. Barzel, Linda K. Massey; June 1998
- "Nutrition and Diagnosis Related Care: Fifth Edition"; Sylvia Escott-Stump; 2002
- "The American Journal of Clinical Nutrition"; Dietary Protein, Calcium Metabolism, and Skeletal Homeostasis Revisited; Jane E. Kerstetter, et al.; September 2003
- "The American Journal of Clinical Nutrition"; A High Ratio of Dietary Animal to Vegetable Protein Increases the Rate of Bone Loss and the Risk of Fracture in Postmenopausal Women; Deborah Sellmeyer, et al.; January 2001