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Protein powder


Related terms
Author information
Types of protein powders

Related Terms
  • Adequate protein diet, Barry Sears, carbohydrate, diet, fat, low carbohydrate diet, protein.

  • The Zone diet is an unproven dietary regime, which has been popularized by Dr. Barry Sears through sales of his 1995 book, The Zone. Despite claims made in the book, there is little available research to support its overall benefit.
  • The Zone diet is a calorie-restricted diet that provides adequate protein, moderate levels of carbohydrates, essential fats and micronutrients spread through three meals and two snacks that approximately maintain the protein-to-carbohydrate ratio throughout the day.
  • Proponents believe that the Zone diet promotes optimal metabolic efficiency in the body by balancing the hormones insulin and glucagon. Insulin is responsible for converting, in the blood, incoming nutrients into cells. Glucagon regulates glucose in the liver. Overall, the Zone's food plan consists of a dietary intake of 40% carbohydrates, 30% protein and 30% fat.
  • Under this diet, recommended foods include fruits and vegetables (fresh or frozen), oatmeal (whole grain), protein powder (e.g. soybean isolate), chicken, turkey, lean beef, fish, low-fat cottage cheese, soy food, nuts (e.g. almonds, cashews, macademia, pistachios), extra virgin olive oil, natural sweeteners, such as fructose or stevia.

Theory / Evidence
  • Recent research seems to indicate that a low total caloric intake is associated with longer life expectancy. Based on animal studies, animals eating calorie-restricted diets may live 1.5 to 2 times as long as animals eating high-calorie diets. Theoretically, similar effects may occur in humans. The caloric restriction recommended by the Zone diet is below that of the average American and may be of benefit in weight loss and if maintained over decades in increasing life expectancy. On the other hand, athletes in training will likely suffer from decreased performance if restricted to the low calorie diet recommended by the Zone.
  • Despite proposed benefits, currently there are no high quality clinical trials available about the Zone diet or similar diets consisting of the recommended 40% carbohydrates, 30% fat, and 30% protein. The Zone diet is quite complex in terms of caloric restriction, ratio of carbohydrates/protein//fat, spacing of meals, preferential intake of certain fats, and avoidance or inclusion of a few specific foods.


Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Cheuvront SN. The zone diet and athletic performance. Sports Med. 1999;27(4):213-228.
  2. Natural Standard: The Authority on Integrative Medicine.
  3. Sears B. The Zone Diet and athletic performance. Sports Med. 2000;29(4):289-294.

Types of protein powders
  • Egg, whey, and soy contain the full spectrum of essential amino acids. These compounds are termed "essential" because they cannot be produced through metabolic processes within the body but must be consumed daily from the foods. All three protein types also score equally highly on the PDCAAS (Protein Digestibility-Corrected Amino Acid Score), with a top ranking score of 1.0.
  • Egg protein powder: Historically, egg protein powders were regarded as the gold standard of proteins, particularly among body builders. They should be avoided in those allergic to eggs or chicken.
  • Rice protein powder: Rice protein powder is derived from the endosperm of grains by the process of separating proteins and carbohydrates. It is though to be the most hypoallergenic protein source, meaning that it produces the least allergic reactions. It has an excellent amino acid profile, very close to that found in mother's milk. Rice protein is also highly digestible and low in ash. It may be used to fortify bars, or it may be added to extruded (process by which feed has been pressed, pushed, or protruded through orifices under pressure) products, baked goods, meal replacement systems and nutritional supplements. It has also been used in cat and dog food, aquatic feeds, calf milk replacement and piglet food.
  • Soy protein powder: Soy protein has been used for centuries in Asia as a nutritional source of protein and also as a medicine. The first use of soy formula in the United States was in 1909 when the soy protein based formulas used soy flour, which often caused gastrointestinal problems. In mid 1960, a soy protein isolate was used, reducing gastrointestinal problems. In October 1999, products containing soy became very popular when the U.S. Federal Food and Drug Administration (FDA) approved manufacturers to label soy protein products as helping to reduce the risk of heart disease. The structure of soy protein most closely resembles that of meat protein and therefore can provide an important meat substitute for vegetarians and those individuals wishing to regulate meat consumption.
  • Whey protein powder: Whey is the watery part of milk that separates from the curds, as in the process of making cheese. Whey protein powder is a concentrated source of non-essential and essential amino acids provided in powder form. As a supplement, whey protein powder may be effective in increasing muscle tissue repair for body builders and athletes in general. High concentrations of branched chain amino acids are proposed to allow for direct uptake by muscle during exercise. Those allergic to milk products should not take whey protein powders. Whey is often the protein supplement of choice for athletes reliant on speed and stamina. It is also rich in tryptophan, a precursor of serotonin, which is commonly referred to as the "feel-good" neurotransmitter, and has been shown to lower stress levels and improve memory in experimental subjects.
  • Other protein powders: Casein, fish, colostrums, and hemp protein powders are also available.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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