Archive | May, 2016

Why Is Optimizing Protein Intake So Important?

23 May

Why Is Optimizing Protein Intake So Important?

By Tim Skwiat, MEd, CSCS, Pn2

When it comes to improving overall health, performance, body composition, appetite control, and satiety, there is arguably not a single more effective, well-established dietary factor than optimizing one’s protein intake. Research has shown that consuming diets higher in protein are not only safe for otherwise healthy individuals, they may provide a host of benefits. Higher protein diets may:

  • Accelerate fat loss and spare lean body mass while following a reduced-calorie diet.
  • Attenuate weight regain and contribute to long-term weight maintenance.
  • Optimize 24-hour muscle protein synthesis and facilitate the maintenance or building of muscle mass.
  • Boost metabolic rate.
  • Preserve metabolic rate after weight loss.
  • Increase satiety and improve appetite control.
  • Improve carbohydrate metabolism and glycemic regulation.
  • Increase calcium absorption.

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Establishing the ‘New Normal’

While the Institute of Medicine (IOM) has established a recommended dietary allowance (RDA) of protein intake at 0.8 grams of protein per kilogram of body weight per day (or, about 0.36 grams of protein per pound of body weight), research illustrates quite clearly and convincingly that an increase in dietary protein intake to at least TWICE (i.e., ≥ 1.6g/kg or 0.72 g/lb) that of the IOM recommendations may be “metabolically advantageous,” particularly for individuals looking to improve body composition (e.g., lose fat) as well as older adults (who are likely to lose muscle mass as they age) and physically active folks (e.g., athletes, military personnel, recreational exercisers).1

The International Society of Sports Nutrition’s (ISSN) Position Stand on Protein states that “protein intakes of 1.4–2.0 g/kg/day [0.63 – 0.91 grams of protein per pound] for physically active individuals is not only safe, but may improve the training adaptations to exercise training.” Further, the ISSN states, “While it is possible for physically active individuals to obtain their daily protein requirements through a varied, regular diet, supplemental protein in various forms are a practical way of ensuring adequate and quality protein intake for athletes.”2 Further, the American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada support higher protein intakes in this range to optimize body composition and performance.3

According to a study published in the Proceedings of the Nutrition Society, renowned protein researcher Dr. Kevin Tipton from the University of Sterling suggests that a high-protein diet may be defined by as much as 35% of total daily caloric intake.4 What’s more, in a breakthrough study published in the journal Applied Physiology, Nutrition, and Metabolism, researchers revealed the RDA (Recommended Dietary Allowance) for protein has underestimated protein requirements by as much as 30 – 50%. Using a novel, validated scientific method, researchers have established that folks should be consuming as much as 35% of their total daily caloric intake from protein. Along these lines, researchers posit that one can optimize protein intake by eating 1.5 – 2.2 grams of high-quality protein per pound of body weight per day.5

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Show Me the Data

High-protein diets have been shown to accelerate fat loss and spare lean body mass while following a reduced-calorie diet. In one study published in the Journal of Nutrition, researchers from the University of Illinois found that women consuming 0.72 grams of protein per pound of bodyweight (about 125 grams per day or 30% of their total daily caloric intake) for 10 weeks had a 66% better ratio of fat to lean body mass loss compared to the “normal” protein group (who consumed half the amount of protein). This means the high-protein group lost MORE fat and LESS muscle—despite consuming the EXACT same amount of calories.6

Interestingly, when the same group of researchers, led by Dr. Donald Layman, combined exercise (5 days of walking plus 2 days of strength training), the effects of the high-protein diet were amplified. Over the course of 16 weeks, the folks combining a high-protein diet (about 30% of calories per day) with exercise lost 43% more fat than the “normal” protein group, who consumed the same number of calories and followed the same exercise program. Even more, compared to the normal protein group that dieted without exercise, the high-protein plus exercise group lost 75% more fat over the course of the 4-month study.7

In a recent randomized control trial published in The American Journal of Clinical Nutrition, researchers from McMaster University found that men combining a reduced-calorie high-protein diet (about 1 gram per pound of body weight per day) with a strenuous exercise program lost over 10 pounds of fat in 4 weeks—37% more than the low-protein group eating the same number of calories and performing the same exercise routine. What’s more, the high-protein group gained over 2.5 pounds of muscle­—despite heavy calorie restriction—while the low-protein group experienced no change. That’s the holy grail of body composition: Fat loss PLUS muscle gain!8

In a recent randomized control trial, a group of researchers from UCLA, led by Dr. Lorraine Evangelista, found that study participants consuming a high-protein diet for 12 weeks lost 77% more weight and dropped more than TWICE as much body fat than the standard protein group.9 In another recent randomized control trial, a group of German researchers, led by Dr. Marion Flechtner-Mors, found that folks consuming a high-protein diet for 12 months lost over TWICE as much weight as the standard-protein group.10

In yet another randomized control trial conducted at the University of Navarra in Pampalona, Spain, a research team led by Dr. Idoia Labayen found that obese women consuming a high-protein diet (about 30% of daily caloric intake) for 10 weeks lost nearly 10 MORE pounds (or, 92% more weight) and 88% more fat than the standard-protein group—once again, despite both groups eating the exact same number of calories.11

In another recent study, researchers from the University of California-Davis, led by Dr. Sidika Karakas, found that overweight women consuming a high-protein diet lost THREE times more weight and over SIX times more fat than the standard-protein group despite sticking to the same amount of reduced calories.12

One of the most objective analyses of the effects of an intervention (like high-protein diets) is something called a meta-analysis, in which researchers gather all of the studies on a particular topic and perform a highly sophisticated statistical analysis. Along these lines, in a meta-analysis of 24 weight-loss studies published in the American Journal of Clinical Nutrition, researchers from the University of South Australia found that high-protein diets led to significantly greater losses in body weight and body fat and spared losses in lean body mass and reductions in metabolic rate, which are common with standard-protein, reduced-calorie diets.13

The study authors concluded that, compared to standard-protein diets, high-protein diets (between 25 – 35% of total daily caloric intake) provide benefits for weight and fat loss and for mitigating losses in lean body mass and resting metabolic rate.

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No One-Trick Pony

What’s more, high-protein diets help attenuate weight regain and contribute to long-term weight maintenance. That’s right, not only have high-protein diets been shown to lead to greater fat loss and improvements in body composition during dieting trials, researchers have also found that high-protein diets increase compliance and long-term weight management.14 In a study published in the New England Journal of Medicine, researchers found that after dropping over 20 pounds during an 8-week weight loss trial, folks consuming a higher protein diet (25% of daily caloric intake) maintained body weight over the next 12 months whereas individuals consuming a standard-protein diet regained some of the weight lost.15

As mentioned above, high-protein diets also help preserve metabolic rate after weight loss.16 A common concern and consequence of standard-protein, reduced-calorie diets is a significant decline in metabolic rate, which frequently leads to weight regain. However, studies have shown that high-protein diets may conserve metabolic rate, and therefore, prevent weight regain. In one study published in the Journal of the American Medical Association, researchers found that metabolic rate was conserved to a significantly greater extent in folks who consumed a higher protein diet (30% of total calories) compared to individuals who consumed a lower protein diet (20% of total calories).17

One way by which high-protein diets may improve weight-loss outcomes is through increased satiety and improved appetite control. High-protein meals boost satiety, which means that protein-dense foods are much more likely to make you feel full and satisfied.18 What’s more, diets rich in high-quality proteins improve appetite control, as well as reduce daily food intake.19 In a recent study published in the Nutrition Journal, researchers from the University of Missouri found that consuming higher protein, dairy-based snacks (e.g., yogurt) improved satiety, appetite control, and limited subsequent food intake when compared to higher fat and higher carbohydrate-based snacks.20

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Balanced Bites

Many people tend to follow a skewed pattern of protein intake throughout the day. In other words, they might have a carbohydrate-dense breakfast (e.g., oatmeal, cereal, bagel) that contains just a few grams of protein, and at lunch, they may have a salad, sandwich, and/or soup that contain less than 20 grams of protein. Then, at dinner, they tend to have a large meal with their largest portion of protein for the day.

In fact, many people consume as much as 50% of their daily protein intake at a single meal in the evening.21 Contrary to this common pattern (referred to as a “skewed” intake of protein), research shows us that a “balanced” intake of protein throughout the day appears to be optimal to take advantage of the many beneficial attributes of protein.

For instance, in a study published in The Journal of Nutrition, researchers found that balancing protein intake over the course of three meals (about 30 grams of protein per meal) significantly increased muscle protein synthesis (by 25%) when compared to a “skewed” protein intake typical of the American diet.22

Why is this so important? Maximizing protein synthesis is paramount to looking, feeling, and performing your best regardless of your age or goals, and it’s especially important for improving body composition, optimizing metabolism, improving carbohydrate tolerance, avoiding age-related declines in muscle mass and metabolic rate, improving performance, and optimizing physical function.

In a separate study published in the American Journal of Physiology, researchers from McMaster University discovered equally impressive findings when they compared a balanced to a skewed protein intake combined with calorie restriction (i.e., dieting). In general, dieting results in a marked decrease in muscle protein synthesis, which typically leads to muscle loss. In fact, losses in lean mass may account for as much as 25% of the weight lost.23,24

The researchers found that a skewed protein intake combined with calorie restriction led to significantly greater reductions in muscle protein synthesis. In other words, a balanced protein intake “rescued” much of the normal decline seen in protein synthesis with dieting. Even more, they found that combining resistance training with a balanced protein intake completely rescued the decline in protein synthesis seen with energy restriction and skewed protein intake.25

As far as how much protein to eat, the research suggests at least 30 grams per meal (3 – 4 meals per day) as a starting point. More specifically, researchers suggest that about 0.18 grams per pound of bodyweight per meal seems to be optimal.26

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Take-Home Points

  • Optimizing protein intake is a well-established nutrition priority for looking, feeling, and performing your best.
  • Studies show that higher protein intakes accelerate fat loss, preserve lean body mass, promote recovery and performance, increase satiety, improve appetite control, reduce cravings, improve glycemic control, preserve metabolic rate, and attenuate weight regain.
  • The evidence suggests that an optimal protein intake may be between 0.7 – 0.9 grams of protein per pound of bodyweight per day as a starting point.
  • Research also suggests that a balanced intake of protein (versus a skewed intake) throughout the day may be optimal to maximize muscle protein synthesis. Based on the current body of research, an intake of around 0.18 grams of protein per pound of bodyweight per meal may be a good starting point.
  • Combining resistance training with an optimal protein intake appears to be superior (for body composition, health, performance) than a higher protein intake alone.
  • High-quality sources of protein are likely best and include: lean meats, poultry, fish/seafood, and wild game (preferably pasture-raised, wild, organic, etc., when appropriate); eggs (preferably pasture-raised); dairy (e.g., Greek yogurt, cottage cheese; preferably organic); protein supplements. [Note: Many protein studies use milk-based protein supplements (e.g., whey, casein), which are considered superior due to their protein quality (e.g., leucine content) and are often used to establish key baselines.]

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References:

  1. Pasiakos SM. Metabolic Advantages of Higher Protein Diets and Benefits of Dairy Foods on Weight Management, Glycemic Regulation, and Bone: Benefits of higher protein…. J Food Sci. 2015;80(S1):A2-A7. doi:10.1111/1750-3841.12804.
  2. Campbell B, Kreider RB, Ziegenfuss T, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2007;4(1):8. doi:10.1186/1550-2783-4-8.
  3. Rodriguez NR. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Am Diet Assoc. 2009;109(3):509-527. doi:10.1016/j.jada.2009.01.005.
  4. Tipton KD. Efficacy and consequences of very-high-protein diets for athletes and exercisers. Proc Nutr Soc. 2011;70(02):205-214. doi:10.1017/S0029665111000024.
  5. Pencharz PB, Elango R, Wolfe RR. Recent developments in understanding protein needs – How much and what kind should we eat? Appl Physiol Nutr Metab. April 2016:1-4. doi:10.1139/apnm-2015-0549.
  6. Layman DK, Boileau RA, Erickson DJ, et al. A reduced ratio of dietary carbohydrate to protein improves body composition and blood lipid profiles during weight loss in adult women. J Nutr. 2003;133(2):411-417.
  7. Layman DK, Evans E, Baum JI, Seyler J, Erickson DJ, Boileau RA. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. 2005;135(8):1903-1910.
  8. Longland TM, Oikawa SY, Mitchell CJ, Devries MC, Phillips SM. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr. 2016;103(3):738-746. doi:10.3945/ajcn.115.119339.
  9. Evangelista LS, Heber D, Li Z, Bowerman S, Hamilton MA, Fonarow GC. Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study. J Cardiovasc Nurs. 2009;24(3):207-215. doi:10.1097/JCN.0b013e31819846b9.
  10. Flechtner-Mors M, Boehm BO, Wittmann R, Thoma U, Ditschuneit HH. Enhanced weight loss with protein-enriched meal replacements in subjects with the metabolic syndrome. Diabetes Metab Res Rev. 2010;26(5):393-405. doi:10.1002/dmrr.1097.
  11. Labayen I, Díez N, González A, Parra D, Martínez JA. Effects of protein vs. carbohydrate-rich diets on fuel utilisation in obese women during weight loss. Forum Nutr. 2003;56:168-170.
  12. Kasim-Karakas SE, Almario RU, Cunningham W. Effects of protein versus simple sugar intake on weight loss in polycystic ovary syndrome (according to the National Institutes of Health criteria). Fertil Steril. 2009;92(1):262-270. doi:10.1016/j.fertnstert.2008.05.065.
  13. Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012;96(6):1281-1298. doi:10.3945/ajcn.112.044321.
  14. Layman DK, Evans EM, Erickson D, et al. A Moderate-Protein Diet Produces Sustained Weight Loss and Long-Term Changes in Body Composition and Blood Lipids in Obese Adults. J Nutr. 2009;139(3):514-521. doi:10.3945/jn.108.099440.
  15. Larsen TM, Dalskov S-M, van Baak M, et al. Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance. N Engl J Med. 2010;363(22):2102-2113. doi:10.1056/NEJMoa1007137.
  16. Soenen S, Martens EAP, Hochstenbach-Waelen A, Lemmens SGT, Westerterp-Plantenga MS. Normal protein intake is required for body weight loss and weight maintenance, and elevated protein intake for additional preservation of resting energy expenditure and fat free mass. J Nutr. 2013;143(5):591-596. doi:10.3945/jn.112.167593.
  17. Ebbeling CB, Swain JF, Feldman HA, et al. Effects of dietary composition on energy expenditure during weight-loss maintenance. JAMA. 2012;307(24):2627-2634. doi:10.1001/jama.2012.6607.
  18. Halton TL, Hu FB. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. J Am Coll Nutr. 2004;23(5):373-385.
  19. Leidy HJ. Increased dietary protein as a dietary strategy to prevent and/or treat obesity. Mo Med. 2014;111(1):54-58.
  20. Ortinau LC, Hoertel HA, Douglas SM, Leidy HJ. Effects of high-protein vs. high- fat snacks on appetite control, satiety, and eating initiation in healthy women. Nutr J. 2014;13:97. doi:10.1186/1475-2891-13-97.
  21. USDA Agricultural Research Service. Energy Intakes: Percentages of Energy from Protein, Carbohydrate, Fat, and Alcohol, by Gender and Age, What We Eat in America, NHANES 2009–2010.; 2012. http://www.ars.usda.gov/Services/docs.htm?docid=18349.
  22. Mamerow MM, Mettler JA, English KL, et al. Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. J Nutr. 2014;144(6):876-880. doi:10.3945/jn.113.185280.
  23. Weinheimer EM, Sands LP, Campbell WW. A systematic review of the separate and combined effects of energy restriction and exercise on fat-free mass in middle-aged and older adults: implications for sarcopenic obesity. Nutr Rev. 2010;68(7):375-388. doi:10.1111/j.1753-4887.2010.00298.x.
  24. Areta JL, Burke LM, Camera DM, et al. Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit. AJP Endocrinol Metab. 2014;306(8):E989-E997. doi:10.1152/ajpendo.00590.2013.
  25. Murphy CH, Churchward-Venne TA, Mitchell CJ, et al. Hypoenergetic diet-induced reductions in myofibrillar protein synthesis are restored with resistance training and balanced daily protein ingestion in older men. Am J Physiol – Endocrinol Metab. 2015;308(9):E734-E743. doi:10.1152/ajpendo.00550.2014.
  26. Moore DR, Churchward-Venne TA, Witard O, et al. Protein Ingestion to Stimulate Myofibrillar Protein Synthesis Requires Greater Relative Protein Intakes in Healthy Older Versus Younger Men. J Gerontol A Biol Sci Med Sci. 2015;70(1):57-62. doi:10.1093/gerona/glu103.

 

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