People think of proteins as the body building nutrients, the material of strong muscles, and rightly so. No new living tissue can be built without them, for proteins are part of every cell, every bone, the blood, and every other tissue. Proteins constitute the cells’ machinery- they do the cells’ work. The energy to fuel that work comes primarily from carbohydrate and lipid.
Protein makes up 50% of your body weight, is present in every cell of the body, and vital to all life functions.
Proteins are formed by complex configurations of amino (containing nitrogen) acids. There are twenty common amino acids making up all proteins in the human body. They are:
Alanine, Arginine (ch), Asparagine, Aspartic acid, Cysteine, Glutamic acid, Glutamine (ce), Glycine, Histidine, Isoleucine (e), Leucine (e), Lysine (e), Methionine (e), Phenylalanine (e), Proline, Serine, Threonine (e), Tryptophan (e), Tyrosine, Valine (e)
The human body contains an estimated 10,000 to 50,000 different kinds of proteins. Proteins from food do not provide body proteins directly, but rather supply amino acids from which the body makes its own proteins.
The body can make over half of the amino acids for itself; the protein in food does not need to supply these. There are other amino acids that the body cannot make, and some that it cannot produce quickly enough to meet its needs. The proteins in foods must supply these amino acids to the body; they are therefore called essential amino acids. The essential amino acids are designated by an (e) after their name.
Also important to point out is that sometimes a nonessential amino acid can become essential. During illness or conditions of trauma, or in other special circumstances, the need for an amino acid that is normally nonessential may become greater than the body’s ability to produce it. In such circumstances, that amino acid becomes essential (e.g., glutamine). Glutamine is considered a “conditionally essential” (ce) amino acid.
Enzymes are Proteins
Enzymes are proteins essential to all life processes. They assemble smaller molecules into larger molecules and they disassemble larger molecules into smaller molecules.
When you consume a protein food, it is broken down into amino acids by enzymes. The amino acids enter the cells of the body, where enzymes put the amino acids back together in long chains determined by genes. The chains fold and twist back on themselves to form the proteins the body needs. Day by day, in billions of reactions, these processes repeat themselves, and life goes on.
Antibodies and Some Hormones are Proteins
While it is common thinking to equate protein with skeletal muscle, the 10 to 50 thousand proteins in the body are not only present to make you buff. In addition to enzyme proteins, antibodies are also proteins. Antibodies are major proteins in the blood acting against viruses, bacteria, and other disease agents. These proteins are so effective that if a million bacterial cells are injected into the skin of a healthy person, fewer than ten are likely to survive for five hours. Without sufficient protein, your body cannot maintain its resistance to disease. Hormones like thyroid and insulin are also proteins with important physiological functions.
Adequate Dietary Protein Necessary
In everyday life, tissue is being broken down and replaced, some quicker than others are. The body uses protein to build all of its new tissues and to repair damaged tissues. The cells that line the intestinal wall, for instance, only live for 3 days; they are constantly being shed and must be replaced. When tissues break down the amino acids in the protein – tissues are liberated and the body can reuse them. However, even though amino acids can be recycled from damaged and repaired tissue, you need to eat protein-rich foods everyday to replace the protein you continuously lose.
National recommendations for adult protein consumption are approximately .8g/kg bodyweight/day. What this means is that according to federal guidelines, the typical adult who weighs 150 pounds does not require more than 55 grams of protein per day ((150 / 2.2) X. 8).
But You Are Not Typical
The federal guidelines for adequate protein consumption are inadequate for most people losing weight or actively using resistance training to pursue real skeletal muscle growth. Research is on my side. The totality of the research indicates that when you are:
- In a hypocaloric (less calories eaten than you need to maintain weight) state,
- Actively pursuing muscle growth with resistance training, or
- Engaging in consistent vigorous exercise,
that you should consume more than the federal guidelines for maximum success and muscle preservation.
Most of the adult protein-needs research done by the World Health Organization and other National and International authorities has only involved sick or healthy, but stable individuals. Once you reach the status of “adulthood” and have stopped growing, the belief by mainstream nutrition authorities is that your needs will not be greater than the federal guidelines discussed above. I can agree with this. However, if you are purposely losing, weight is not stable. Further, if you are adding new skeletal muscle you are also not stable.
Like carbohydrates and lipids, proteins are composed of carbon (C), hydrogen (H), and oxygen O)- but proteins are different in that they also contain nitrogen (N). Researchers can trace nitrogen retention in, and excretion from, the body after test subjects consume protein-rich foods. Much of the research determining adequate protein needs for the dieter or athlete is centered around the concept of nitrogen balance – or more appropriately called “nitrogen state”. You can be in a positive, neutral or negative nitrogen state. Most non-dieting, non-exercising healthy adults are in a neutral nitrogen state (i.e., nitrogen balance) – they are utilizing and excreting nitrogen at the same rate as it is being consumed. As you might expect, however, being in a positive nitrogen state is desirable for adding new muscle and being in a negative nitrogen state is undesirable. Here are some examples that I hope will make things more clear with regard to nitrogen status:
- Normal, healthy non-dieting, non-exercising adults are in a neutral nitrogen state – neither positive nor negative.
- Growing children and pregnant women are in a positive nitrogen state.
- People who are starving or fasting are in a negative nitrogen state.
- People suffering from anorexia, sickness, and trauma are in a negative nitrogen state.
- When you are in a negative nitrogen state, your body will turn to its own proteins (muscle) for energy.
Lifestyle Guidelines for Protein Needs
My protein recommendations for anyone losing weight and/or actively pursuing increased skeletal muscle mass mirror those of respected protein experts in this country and abroad. The research is clear. Lifestylers need slightly more than twice the federal guidelines of .8g/kg bodyweight/day. It is easier to understand if I say that you should consume approximately 1 gram of protein for every pound of fat-free mass you have. On a percentage of calories consumed basis, it can best be said this way – consume 30-50 percent of your total caloric intake as proteins.
Is Leanness Lifestyle High-Protein?
Leanness Lifestyle is a high-protein plan if we’re idiots and only look at the base RDA as our guide. But remember, the RDA was never designed to account for those losing weight AND we’re not idiots! The RDA was designed to determine adequate protein needs to prevent deficiency for stable-weight conditions. Optimal intake should not be confused with deficiency prevention.
Leanness Lifestyle protein recommendation are first based on the realities of our unstable weight condition–that we are losing weight. Secondly we are very interested in preserving and most often adding lean body mass. These two conditions; unstable weight and desire for preservation of lean body mass necessitate increased protein intake compared to the base RDA.
The average man in the U.S. is 5’9″ and weighs 194 pounds. The average woman in the U.S. is 5’4″ and weighs 164 pounds.
My protein recommendations for anyone losing weight and/or actively pursuing increased skeletal muscle mass mirror those of respected experts in this country and abroad who consider the state of weight-loss and the preservation of lean body mass. Instead of 0.8g/kg bodyweight/day I recommend about 1.6g/kg bodyweight/day. It may be easier to understand if I say that as a percentage of calories consumed basis I recommend 30-50 percent of your total caloric intake from quality proteins.
For someone consuming 1600 calories per day (pretty typical for men cutting fat) the recommended protein intake would be 120-200 grams per day. For someone consuming 1200 calories per day (pretty typical for women cutting fat) the recommended protein intake would be 90-150 grams per day.
Protein Supplements and the Best Source
Carbohydrate-rich foods are derived from plants. The highest quality, complete, protein-rich foods are derived from animals. When you are following the Lifestyle, assuming you are not a vegetarian (I’ll cover you later), you’ll get much of your protein from lower-fat animal flesh (e.g., chicken, turkey, tuna and lean beef), quality-fat animal flesh (e.g., mackerel, salmon, trout), egg whites, and dairy products (e.g., cottage cheese, fat-free cheese, 1% or fat-free milk).
A mixed diet is one in which the food consumption is broad. I believe food selection should remain varied to prevent a deficiency of any one required nutrient. While some athletes remain convinced that strict limitations, avoidance, and a narrow selection of principle foods is optimal for their performance (chicken and broccoli only people), research does provide credence to the notion that variety is truly the spice of life, health and optimal performance. Should there be a different mode of thinking when considering supplementation with protein-rich supplements?
Whey-based protein powders are the number one selling protein powders. Quality dietary supplements utilizing these proteins are obtained from manufacturing facilities that produce cheddar cheese. During cheese production, the milk is curdled, separating the curd (casein) from the whey. Only after careful handling, temperature control and proper drying techniques will a quality protein powder evolve from curd or the watery, liquid, mother-whey that results during cheese production.
Since whey is enjoying a solid spot at the top of the supplement sales chart, I will review some of its strengths and weaknesses. Then you can decide if whey is really the only protein worth considering. Whey
protein can be a rich source of immunoglobulins. Immunoglobulins are immuno-enhancing and considered a strong functional property of whey proteins. Of the known dietary proteins, whey proteins are the richest source of branched chain amino acids (BCAAs are L-leucine, L-valine, L-isoleucine), supplying four grams of BCAAs per 20 grams of whey protein. A BCAA load before intense exercise may offer athletes an anabolic advantage during intense training periods. BCAAs are depleted from muscle tissue during strenuous exercise and are believed to support energy dependent processes during heavy training. Some quality whey proteins with minimal denaturation (denaturation occurs most commonly as a result of chemical interaction or excessive exposure to high temperatures during production) contain serum albumin. Serum albumin is also rich in glutamylcysteine groups. This compound may be an important promoter of glutathione production within the body. Glutathione is an extremely important and potent antioxidant. Finally, regardless of the protein quality measure used (i.e., P.E.R., BV etc.), whey protein is considered a superior protein to many and the best, including egg.
At this point, it would appear that whey protein is hands-down the best protein available and there should be no need to look further. As nature would have it, however, things are not perfect in whey land. Recall that essential amino acids are those amino acids which your body cannot produce and which you must obtain from food. Whey proteins are not a good source of the essential amino acid L-Phenylalanine. Whey protein is also low in the conditionally essential amino acid L-Arginine.
Another protein source, still popular among bodybuilders and protein experts is egg. In fact, it is still considered a reference protein due to its amino acid profile and quantity of essential amino acids. Reference proteins are generally recognized as those that are of such high quality that other proteins can be compared to them when considering human needs. Before whey and whey combinations were studied, egg protein enjoyed a lengthy history of being recognized as the highest quality protein known. One problem with egg is that most of the research has involved whole egg, and not simply the egg white (egg albumen). One whole egg contains approximately 5 grams of fat. Protein powders containing egg do not contain the yolk portion (this is where the fat resides), but instead only contain egg albumen (white). Egg albumen, while still a quality protein, is generally recognized as having a lower value biologically than whole egg. The biological value is one measure of how well a protein is retained by an organism.
Just as we are advised to consume a widely, varied diet, the wisest recommendation can also be extended to concentrated protein supplements. The same ideology that proclaims that variety ensures required nutrients with no deficiencies of any one nutrient, also applies to amino acids and functional properties unique to each protein you consume. The purpose of this section is not to have you becoming intimidated from your favorite egg, soy or whey protein powders. If you are following the Lifestyle, you are also eating on a daily and weekly basis a variety of foods containing protein, such as meat, milk, soy, fish or nuts. Achieving balance for required nutrients, health and performance is not difficult. Seek variety and quit searching for the “perfect” one food or protein.
Vegetarians, Traditionally a Walking Protein Shortage?
Vegetarians may be at increased risk for protein deficiencies because animals provide the best, complete protein sources we know of today. There are three basic classifications of vegetarians:
- Vegan – pure NO ANIMAL eater
- Lactovegan – consumes some dairy
- Lactoovovegan – consumes dairy and eggs
The greatest problem with nearly all plant proteins is their incompleteness. This means is they are lacking one or more essential amino acids. Soy is an exception. Many vegetarians combine foods to insure consumption of all essential amino acids. . Some common combinations are; milk and cereal, peanut butter and bread, beans and rice, beans and corn tortillas, and macaroni and cheese.
Strict vegans can meet their Lifestyle protein needs by consuming more foods such as soy protein powder, tofu, tempeh and soy nuts. Lactovegans and Lacto-ovovegans can follow my advice for vegans plus make a concerted effort to consume more low-fat varieties of the limited animal products they are willing to eat.
Other nutrients commonly lacking in a poorly managed diet and that a vegetarian should be concerned with: Vitamin B12, Vitamin D, Riboflavin, Calcium, Zinc, and Iron. In addition to eating a variety of foods known to be rich sources of these vitamins and minerals, a quality multivitamin/mineral is recommended each day.
Protein and Kidney Strain
It is important to realize that you will not be eating excessive amounts of protein. You will be eating a very healthy amount to support weight-loss and the preservation of muscle mass.
Eskimos, the Hunter-gatherer, body builders and people who are very carbohydrate sensitive have maintained higher protein diets for years without any kidney abnormalities. Many people are likely to realize improvements in kidney function by reducing the intake of refined carbohydrates and saturated fat while increasing protein to within the guidelines of the Lifestyle.
There are two classes of individuals who should concern themselves with the protein suggestions of the Lifestyle: 1). Those with pre-existing kidney abnormalities, 2). Diabetics and others suffering from a disease known to negatively affect kidney function. Always speak to your doctor about the Lifestyle if there is any question about the health of your kidneys or you are being treated for any medical conditions that may be affected by a moderately high protein intake.
Protein and Osteoporosis
Although some studies show that increased animal protein causes loss of calcium in the urine, the amount that causes the increase is not specific. The amount is also variable and the results are still controversial. In fact, recently a study agrees with ancestral data, which linked increased amounts of protein in pre-menopausal women with increased bone density.
Let’s look at this finding in context with osteoporosis as a whole, and our ancestry. This will show the problem of isolating study findings out of context.
For every complex problem, there is a simple solution, and that simple solution will be wrong.
It is well documented that calcium, the major component of bone, is essential to maintain strong bones. Americans, who drink more milk and eat more dairy than any other country, have one of the highest incidences of osteoporosis. Orientals who eat no dairy have virtually no osteoporosis.
The process of bone formation and maintenance is a complex physiological process. Drinking more milk or taking calcium supplements is not the entire solution for obliterating the problem of osteoporosis. This thinking is simplistic, naïve and wrong. Without going in to an explanation of the physiology of bone formation, I will address a few of the major risks of bone loss and protective traits necessary for bone development and maintenance.
Bone is not only composed of calcium but other micronutrient minerals just as important for proper formation. The more important ones include:
All of these minerals, especially magnesium, are important to orchestrate the formation of bone. No matter how much calcium you consume, there will not be adequate bone formation and maintenance if other dietary practices create a deficiency of these nutrients. Further, excess calcium that does not get absorbed into bone may find itself in the soft tissues, such as the arteries, kidneys and joints. This can play a role in heart disease, kidney stones and osteoarthritis.
In order for the body to effectively utilize calcium, it needs approximately equal amounts of magnesium. Magnesium was found readily in the diet of our ancestors in nuts, seeds and vegetables. Therefore, we did not need to develop the ability to store magnesium. Because calcium-rich foods such as dairy were not available thousands of years ago, the body developed the ability to store calcium.
The bottom-line – Even if you do consume enough dietary calcium, if you do not have enough of the other minerals, it will not be used the most effectively.
Our basic need for dietary calcium is not that high. However, because of many dietary habits highly prevalent in western societies, there is so much calcium loss that increased intake is necessary. Commonly eaten or used substances have also been clearly shown to effect calcium metabolism and bone formation as well. These substances and habits will interfere not only with calcium absorption, but can leech it from the bones and cause the loss of calcium from the body.
- Insufficient vitamin D obtained from adequate amounts of sun light
- Phosphorous – found in high amounts in soda – especially diet soda.
- Excessive Sodium – found in large amounts in processed foods.
- Excessive caffeine
- Excessive sugar
- Excessive alcohol consumption
- Antacids with aluminum
- Certain cholesterol medications
- Excess bran
- Physical inactivity – Studies show that if activity is increased, then bone uptake of calcium increases regardless if extra calcium supplementation is taken. Two weeks of bed rest is equivalent to 1 year of aging. It increases calcium loss 50 fold.
- Hormonal loss – menopause or loss of menstrual cycles, estrogen, progesterone and testosterone
The following are still controversial:
- Excess protein – especially that from animals may increase calcium excretion.
- Fat inadequate diets- the essential fatty acids are crucial to bone formation
If you are a couch potato and drink diet soda and coffee to excess, enjoy your daily fat-free cookies, eat prepared and processed foods high in sodium and think that by keeping protein intake very low you’ll be safe from osteoporosis, then you need to wake up.
How to Prevent Osteoporosis
Populations with very low incidence of osteoporosis are very physically active in the outdoors and exposed to plenty of natural sunlight. They eat the right type of fats and loads of fresh vegetables and fruit. They eat less refined sugar, less processed foods with excess sodium, do not smoke, don’t binge on alcohol, and they don’t live on caffeine and sodas high in phosphorous.
Even though laboratory studies show protein may increase calcium loss, anthropological studies of Hunter-gatherer populations have found the bones of these people to be extremely strong, even stronger than their agriculturally raised brothers. This occurred even though Hunter-gatherers ate diets consisting of 50-60 percent animal protein. The difference in density between these two populations is so great that on excavation, researchers can distinguish immediately the bones of the Hunter-gatherer populations from the farming agricultural populations.
Perhaps the Hunter-gatherer populations were more physically active. Perhaps they consumed more of the essential fatty acids or avoided the phytic acid found in grains. The point here is you just cannot make recommendations for a complex illness based on the results of one study, on one variable taken out of context of a complete lifestyle.
Research In Support Of My Recommendations
1. CONCLUSIONS: These results indicate that approximately 2.3 g x kg(-1) or approximately 35% protein was significantly superior to approximately 1.0 g x kg(-1) or approximately 15% energy protein for maintenance of lean body mass in young healthy athletes during short-term hypoenergetic weight loss.
David says: Maybe you don’t see yourself as an athlete just because you’re losing body fat. What is different about YOU vs. an athlete? Very little. You are an athlete. How? You will, if not already, be on the quest to add some lean body mass. Lean body mass is precious. It burns 3-5 times the calories at rest compared to fat. Whatever we’ve got we want to keep. And for most the goal should be to add some more muscle mass.
We add and keep muscle mass with strength training. Athletes also commonly engage in strength training. You are going to do cardiovascular training. Athletes routinely engage in cardiovascular/aerobic training. You will be eating healthy with a focus on preserving and adding lean body mass. So do athletes. What’s different between you and an athlete? Only that you may not compete. Therefore, it’s not a stretch, at all, to look at athlete studies DURING WEIGHT LOSS.
2. The potential for high-protein diets to confer greater benefit than other diets has been examined using ad libitum and energy restricted diets. Of greatest interest have been the comparisons between high-protein and high-carbohydrate diets. Many trials have reported greater weight loss especially in the context of ad libitum diets over the short-to medium-term, sparing of lean body mass, lowering of triglyceride levels, improved HDL: total cholesterol ratio and improved glycaemic control. Dietary patterns with high-protein intakes are appropriate for weight reduction and weight maintenance and may be useful for those who have high triglyceride levels and other features of the metabolic syndrome.
3. In conclusion, dietary protein contributes to the treatment of obesity and the metabolic syndrome, by acting on the relevant metabolic targets of satiety and energy expenditure in negative energy balance, thereby preventing a weight cycling effect.
4. CONCLUSION: Compared with an energy-restricted standard-protein diet, an isocalorically prescribed high-protein diet provides modest benefits for reductions in body weight, FM, and triglycerides and for mitigating reductions in fat-free mass and resting-energy expenditure.
5. CONCLUSION: Body-weight loss and weight-maintenance depends on the high-protein, but not on the ‘low-carb’ component of the diet, while it is unrelated to the concomitant fat-content of the diet.
6. For years, proponents of some fad diets have claimed that higher amounts of protein facilitate weight loss. Only in recent years have studies begun to examine the effects of high protein diets on energy expenditure, subsequent energy intake and weight loss as compared to lower protein diets. In this study, we conducted a systematic review of randomized investigations on the effects of high protein diets on dietary thermogenesis, satiety, body weight and fat loss. There is convincing evidence that a higher protein intake increases thermogenesis and satiety compared to diets of lower protein content. The weight of evidence also suggests that high protein meals lead to a reduced subsequent energy intake. Some evidence suggests that diets higher in protein result in an increased weight loss and fat loss as compared to diets lower in protein, but findings have not been consistent. In dietary practice, it may be beneficial to partially replace refined carbohydrate with protein sources that are low in saturated fat. Although recent evidence supports potential benefit, rigorous longer-term studies are needed to investigate the effects of high protein diets on weight loss and weight maintenance.
7. Conclusion: For years, authors of some fad diets have advocated raising the percentage of dietary protein in the overweight, although not until recently have studies begun to investigate the effects of high protein diets on weight loss.
Convincing evidence exists that protein exerts an increased thermic effect when compared to fat and carbohydrate. The increased amount of energy attributable to this thermic effect is probably too small to have a visible effect on weight loss in the short term, but over periods of months or years, this difference may become significant, both clinically and statistically.
Evidence is also convincing that higher protein diets increase satiety when compared to lower protein diets. This may enhance a dieter’s ability to “stick with” a hypocaloric diet over the long term. Evidence is suggestive that higher protein diets decrease subsequent energy intake at the next meal compared to lower protein diets, although the studies are not consistent.
Our review suggests that higher protein diets may significantly increase total weight lost and possibly percentage of fat lost when compared to a lower protein diet in the short term. Possible mechanisms include an increased satiety and decreased subsequent energy intake with higher protein diets. All 5 investigations that utilized an ad lib intake found significantly increased weight lost with the higher protein regimens in the short term studies (6 months or less). A higher thermogenesis for protein is a possible mechanism as well, but the studies included in this review were of too short a duration for this to be conclusive; if it does have an effect, this higher thermogenesis is likely to be noticeable only in the longer term. Another possible mechanism is the displacement of carbohydrate, especially refined carbohydrate, in the diet by dietary protein. There is emerging evidence that high glycemic, refined carbohydrates decrease satiety and increase subsequent energy intake. It is likely that several of these mechanisms are working together and are related to one another.
In conclusion, evidence suggests that higher protein diets may have beneficial effects on weight loss in the short term, although most of the studies have been small and inconclusive. More definitive evidence should wait for the results from ongoing long-term trials. Although the optimal amount and sources of protein cannot be determined at this time, the weight of evidence suggests that in dietary practice, it may be beneficial to partially replace refined carbohydrate with protein sources that are low in saturated fat.
8. The role of dietary protein in weight loss and weight maintenance encompasses influences on crucial targets for body weight regulation, namely satiety, thermogenesis, energy efficiency, and body composition. Protein-induced satiety may be mainly due to oxidation of amino acids fed in excess, especially in diets with “incomplete” proteins. Protein-induced energy expenditure may be due to protein and urea synthesis and to gluconeogenesis; “complete” proteins having all essential amino acids show larger increases in energy expenditure than do lower-quality proteins. With respect to adverse effects, no protein-induced effects are observed on net bone balance or on calcium balance in young adults and elderly persons. Dietary protein even increases bone mineral mass and reduces incidence of osteoporotic fracture. During weight loss, nitrogen intake positively affects calcium balance and consequent preservation of bone mineral content. Sulphur-containing amino acids cause a blood pressure-raising effect by loss of nephron mass. Subjects with obesity, metabolic syndrome, and type 2 diabetes are particularly susceptible groups. This review provides an overview of how sustaining absolute protein intake affects metabolic targets for weight loss and weight maintenance during negative energy balance, i.e., sustaining satiety and energy expenditure and sparing fat-free mass, resulting in energy inefficiency. However, the long-term relationship between net protein synthesis and sparing fat-free mass remains to be elucidated.
9. Recent studies have demonstrated that consuming dietary protein at levels above the current recommended dietary allowance (0.8 g · kg(-1) · d(-1)) may attenuate the loss of skeletal muscle mass by affecting the intracellular regulation of muscle anabolism and proteolysis.
10. Bariatric surgery, a highly successful treatment for obesity, requires adherence to special dietary recommendations to insure the achievement of weight loss goals and weight maintenance. Postoperative consumption of protein is linked to satiety induction, nutritional status, and weight loss. Hence, we conducted an extensive literature review to identify studies focused on the following: protein and nutritional status; recommendations for dietary protein intake; the effects of protein-rich diets; and associations between dietary protein intake and satiety, weight loss, and body composition. We found that there have been few studies on protein intake recommendations for bariatric patients. Dietary protein ingestion among this population tends to be inadequate, potentially leading to a loss of lean body mass, reduced metabolic rates, and physiological damage. Conversely, a protein-rich diet can lead to increased satiety, enhanced weight loss, and improved body composition. The quality and composition of protein sources are also very important, particularly with respect to the quantity of leucine, which helps to maintain muscle mass, and thus is particularly important for this patient group. Randomized studies among bariatric surgery patient populations are necessary to establish the exact quantity of protein that should be prescribed to maintain their nutritional status.
11. Medical nutrition therapy plays a major role in diabetes management. Macronutrient composition has been debated for a long time. However, there is increasing evidence that a modest increase in dietary protein intake above the current recommendation is a valid option toward better diabetes control, weight reduction, and improvement in blood pressure, lipid profile, and markers of inflammation. Increasing the absolute protein intake to 1.5-2 g/kg (or 20-30% of total caloric intake) during weight reduction has been suggested for overweight and obese patients with type 2 diabetes and normal kidney function. Increased protein intake does not increase plasma glucose, but increases the insulin response and results in a significant reduction in hemoglobin A(1c). In addition, a higher dietary protein intake reduces hunger, improves satiety, increases thermogenesis, and limits lean muscle mass loss during weight reduction using a reduced calorie diet and increased physical activity. It is preferable to calculate protein intake for patients with diabetes as grams per kilogram of body weight and not as a fixed percentage of total energy intake to avoid protein malnutrition when a hypocaloric diet is used. The relationship between protein intake as grams per kilogram of body weight and albumin excretion rate is very weak, except in hypertensive patients and particularly in those with uncontrolled diabetes. A protein intake of 0.8-1 g/kg should be recommended only for patients with diabetes and chronic kidney disease. Other patients with diabetes should not reduce protein intake to less than 1 g/kg of body weight. This review discusses the effects of different amounts of protein intake in a diabetes meal plan. It particular, it discusses the effects of protein intake on renal function, the effects of protein content on diabetes control, and the effects of increased dietary protein on body weight.
12. Effects of protein intake and gender on body composition changes: a randomized clinical weight loss trial
Researchers in this study cut 500 kcal/d and either fed subjects 1.6g/kg/d protein (PRO) or 0.8g/kg/d protein (CARB) and evaluated total weight loss and lean body mass changes.
PRO was more effective in reducing percent body fat vs. CARB over 12mo weight loss and maintenance. Men lost percent total body fat and trunk fat more effectively than women. No interactive effects of protein intake and gender are evident.
The free FULL article is here http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407769/
13. Red meat intake has been frequently associated with the development of coronary artery disease and type 2 diabetes but vegetable protein has been associated with protection from these diseases. Whether this is related to the protein per se or to the increased polyunsaturated fat or higher fibre levels associated with more vegetarian diets is not clear. High protein diets are associated with greater satiety and in some studies are associated with greater weight loss compared with high carbohydrate diets especially in an ad libitum design. These diets also lower plasma triglyceride and blood pressure and sometimes spare lean mass. There appear to be no harmful effects of high protein diets on bone density or renal function in weight loss studies.
14. Dietary protein in weight management: a review proposing protein spread and change theories
Annual healthcare costs relating to obesity approximate $150 billion in the US alone.
Thus, there would be great utility for dietary strategies that require minimal restriction yet
benefit body composition and metabolic health. Manipulation of dietary macronutrient intake
in favor of protein has shown considerable promise since the 1990s and has gained
increasing support recently.
In the US, the Food and Nutrition Board provides a dietary protein recommendation for
adults of 0.8 g/kg/day known as the Recommended Dietary Allowance (RDA). The World
Health Organization (WHO) recommends 0.83 g/kg/day of high quality protein. Multiple
researchers support the consumption of greater protein than the RDA, arguing that the RDA
is a minimum level for health, not an optimal intake for health indicators such as body
compositionsomething the WHO also notes. Still, there is resistance to
recommending a higher amount of protein to the public.
While some will critique that the satiating effect of higher dietary protein sometimes results
in voluntary hypophagia, leading to an energy intake discrepancy between groups, there
is evidence that increased dietary protein leads to improved body composition and
anthropometrics under iso-, hypo-, and hyper-caloric conditions. Thus, the
traditional dogma of “energy in versus energy out” explaining weight and body
compositional change is not entirely accurate. Another critique is that there are some studies
in which greater protein is no more effective than control. These studies do not find
negative effects on body composition from higher protein, rather benefits are shown that are
the same, but no greater than in controls.
The full free study is here http://www.nutritionandmetabolism.com/content/pdf/1743-7075-9-81.pdf
15. “In addition, high-protein diets are associated with increased satiety and thermogenesis, with a relatively more pronounced loss of fat versus lean mass and improved blood lipid profile compared with low-protein diets.”
16. “Conclusions: Higher-protein diets probably improve adiposity, blood pressure and triglyceride levels, but these effects are small and need to be weighed against the potential for harms.” Blood pressure: Meta-analysis of 15 studies (1186 participants) showed a small statistically significant decrease in systolic blood pressure. Lipid levels: The 21 studies (1368 participants) that reported total cholesterol showed no difference and similar nonsignificant changes. HDL cholesterol was significantly increased with higher-protein diets. C-reactive protein: The pooled effect size of five studies (398 participants) showed no significant difference in CRP. Fasting blood glucose: Pooled analysis of 15 studies (1089 participants) showed no difference in fasting blood glucose. Triglycerides: The 24 studies (1623 participants) included in the meta-analysis demonstrated a moderate statistically significant decrease in triglycerides. There was a greater reduction in triglycerides at 3 months with higher- compared with lower-protein diets. Bone health: There was no difference in total body bone mean difference.
17. In summary, high-protein diets (within 6 months) may have some beneficial effects on weight loss, HbA1C levels and blood pressure in patients with type 2 diabetes. However, further investigations are still required to draw a conclusion.
I Welcome Your Thoughts, Agreements and Arguments
Not every study agrees with the other. Every study published to date doesn’t indicate that more protein is best or needed when losing weight. However, when you consider the “totality of the evidence” there is strong support of an increased dietary-protein need when cutting fat and/or building muscle compared to the average Jane and Joe who are weight-stable and not living their lives like the everyday athletes we all are who want to live at a healthy weight living healthy lives.