Protein: what, when, why, and how?

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The topic of protein is hot! Animal versus plant, one animal versus another, one plant versus another, food versus supplement? How much or how little? When and with what? There are so many ways to approach these questions. Setting aside the political and social issues that surround dietary protein sources, lets focus on the concepts that impact protein and exercise, and then work our way into the details.




Inside your body, a marvelous process of self-repair takes place day in and day out,

and it all has to do with protein, the nutrient responsible for building and maintaining

body tissues. Protein is present everywhere in the body—in muscles, bones,

connective tissue, blood vessels, blood cells, brain cells, skin, hair, and fingernails.

This protein is slowly but consistently being degraded or broken down at varying

rates within different tissues as a result of normal physiological wear and tear and

must be replaced. The younger you are the greater your protein turnover, meaning

that your cells and tissues rejuvenate more frequently. Part of the aging process is

the slowing of protein turnover and cellular rejuvenation. The good news is that

exercise helps with cellular rejuvenation as long as you’ve got all the amino acids

to support the ongoing rebuilding process.


Under any condition of growth—childhood, pregnancy, muscle building—the

body manufactures more cells than are lost. From an energy source such as carbohydrate

or fat, the body can manufacture many of the materials needed to make

new cells. But to replace and build new protein, the body must have protein from

food in the form of the nitrogen-containing amino acids. Unlike carbohydrate and

fat, protein contains nitrogen, and nitrogen is required to synthesize new protein.


Protein, therefore, is absolutely necessary for the maintenance, replacement,

and growth of body tissue. But protein has other uses, too. The body uses protein

to regulate hormone secretion, maintain the body’s water balance, protect against

disease, transport nutrients in and out of cells, carry oxygen, and regulate blood

clotting. Only protein can do these jobs.




You might assume that because aging decreases protein turnover, our dietary need for protein decreases. However, protein needs stay at least the same, and may increase as we age, depending on our health status. Research has shown that the sedentary healthy elderly fair far better when they consume at least 0.5 gram of protein per pound of body weight per day. In aging populations with clinical conditions the recommendation is 0.7-1 gram of protein per pound of body weight per day. We also know that one way to reverse the physical downhill slide of aging is to strength train. Study after study has shown that you can make significant muscle gains well into your 90s if you strength train, and your needs will stay the same as your more youthful counterparts.


Whatever our age and physical condition, we all benefit from movement and physical challenge. Adding more protein to our diets at a level of at least 0.7 to 1.0 gram per pound body weight per day will support the advantageous cellular growth and rejuvenation that comes from exercise.


Another time when we need more protein, not less, is when we follow a diet that contains fewer calories than we need each day. Typical of most weight loss diets, low calorie diets increase our body requirement for protein. In addition, higher protein diets may help control appetite, and support the maintenance of muscle mass during weight loss. The combination of strength training with a slightly higher protein weight loss diet is an ideal combination for maintaining muscle and metabolic rate while losing fat.




It’s clear that we all need protein, and we may need more, and certainly not less, as we age and stay physically fit. The next question is how are you going to feed yourself that protein? The decision between eating protein-rich food or consuming a protein supplement is really a choice of convenience. There is no magical advantage to a supplement other than it is there when you need it. Even for exercisers, there is no difference in recovery between liquid and solid food sources.


We use protein supplements as a matter of convenience, and also when it is easier to consume the amounts needed. As a general rule, it is nearly always better to consume nutrients from wholesome food sources compared to supplemental, engineered food sources. However, whether due to limited appetite, access to food or food preparation, or convenience, protein supplements have become an important part of the diets for boosting protein intake in a wide range of populations including physically active, healthy aging and frail elderly individuals.


Plan on food first. Eat food when you can, and supplements when you must. The array of protein-rich foods delivers not only protein to our diets, but also an outsized selection of other macronutrients, vitamins, minerals, phytochemicals, fibers, food factors, probiotics, prebiotics, and more. Supplements provide the protein that we need, and typically not much else.  They are a targeted solution, but essential when food is not available or is not the best solution.




The topic of plant versus animal protein is quite often dependent on the dietary philosophy of the user. In other words, are you a vegetarian, a vegan or an omnivore? Regardless of your leaning, variety in the diet is a key concept.

All proteins are not the same. Each protein has some modification to its amino acid composition that is unique to its source. Fish protein is different from beef protein, which is different again from egg protein or milk protein. All of these are different from soy protein, which differs from proteins from grains, seeds and other legumes.


Whey protein is clearly the highest value in protein supplements, resulting in the greatest muscle gain for the smallest serving of 20-25 grams. But if you are a big milk drinker, you might choose a soy protein for your supplement to gain variety in your diet and take a slightly larger dose to get the advantage you would otherwise receive from whey. If you are a vegan and eat a lot of soy foods in your diet, you might choose a rice protein supplement over soy, for the variety. While soy is the highest quality of plant proteins, a 40-gram rice protein supplement may perform equally as well. In fact, for plant protein supplements other than soy, this higher dosage may be more effective.




There is some research that says that your muscles don’t care if you eat all your protein at one meal or spread it out during the day. But your body is more than just your muscles. We know that combinations of protein with carbohydrate and healthy fats in meals throughout the day is part of maintaining healthy blood sugar levels all day long, supporting elevated mood and a sense of mental energy, and assisting our coping mechanisms for stress and anxiety.


Fueling your body before exercise gives you the additional energy to push all the way to the end of your workout. If you can eat a snack of easily digestible carbohydrate and a little protein about 90 minutes before exercise, you’ll feel energized going into your workout.  Try combinations like fruit and yogurt, cereal and milk, or a small quinoa bowl with soy milk. If food doesn’t sit well on your stomach before your workout, pure carbohydrate from my favorite workout supplement, Vitargo ( is an ideal choice. You can add the protein after exercise since it’s really there for post-exercise recovery anyway.


Post-exercise recovery shakes are very popular since many people don’t have an appetite after intense exercise, or food just isn’t available in time. A combination of protein and carbohydrate after exercise will boost your body’s recovery processes and make you feel better faster, but whether you use a meal or supplements is a matter of your choice and convenience. Serving sizes of protein range from at least 20-25 grams for whey and animal proteins, and 30-40 grams for soy and other plant proteins. The amount of carbohydrate that you need for recovery depends on the intensity and duration of your workout. The harder and longer your workout, the more carbohydrate you need to refuel your muscles for your next training session. You might put some carbohydrate in your supplement shake and save some for a meal of food to follow later. Remember, emphasize variety!







The table below is from my new book, The New Power Eating. There are so many delicious foods to try and add to your menu plans that are good sources of protein. Try new foods and new ingredients, they all add nutritional richness to your diet. Plan on food first. Eat food when you can, and supplement when you must.

Keep going strong!




Dr. Susan Kleiner is a titan in sports nutrition. Her seminal research on male and female bodybuilders launched the study of the nutritional needs of muscle building, power and strength. Her expertise and research has expanded to hydration, and she is passionate about the nutritional needs of athletic women and girls. She is the founder and owner of the internationally recognized consulting firm, High Performance Nutrition, LLC, and has recently become Director of Science and Communication for Vitargo Global Sciences, Inc. With one foot in the academic world and one in the business world, she authored the best-selling legacy book Power Eating® soon to be published in its fifth edition, The Good Mood Diet, five other popular books, numerous academic chapters and peer-reviewed scientific journal articles, as well as featured columns in all forms of media. Dr. Sue has consulted with professional athletes and teams, Olympians and elite athletes in countless sports. She is currently the High Performance Nutritionist for the Seattle Storm (WNBA) and formerly for the Seattle Reign FC (WNSL), the Seattle Seahawks, the Seattle Supersonics, the Miami Heat, the Cleveland Cavaliers and the Cleveland Browns. She is co-founder and fellow of the International Society of Sports Nutrition and a fellow of the American College of Nutrition, a member of The American College of Sports Medicine and The National Strength and Conditioning Association.

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