high protein diet literature review

THE EFFECTS OF A HIGH PROTEIN DIET ON BODY COMPOSITION DURING

ENERGY RESTRICTED DIETS

Jarrett MooreKINS 7230

Fall 2012

Purpose Determine the effectiveness of a high

protein intake during an energy restricted diet.

Compare the efficacy of high protein vs. high carbohydrate diets.

Compare short term and long term HP diet interventions.

Discuss safety concerns. Review future strategies.

Introduction The use of high protein diets remain a

controversial topic; however, clinical evidence suggests HP diets may be optimal for maintaining FFM during hypocaloric or low calorie diets. 4,11

Protein Protein is ~16%

nitrogen. 8

4kcal/gram of protein

RDA for ProteinSedentary 0.8 g/kg of

body weight 14

Active/Athletes 1.2-1.8 g/kg of body weight 14

Assessing Protein Requirements

Nitrogen balance is used to assess protein requirements. 8

Nitrogen is used because it reflects the use of protein in the body. 8

Measures the difference between nitrogen in and nitrogen excreted. 8

A negative nitrogen balance as a result of low protein intake reflects a loss in FFM. 4, 8, 11

Adequate protein intake may help maintain FFM during low calorie/hypocaloric diets. 4, 11

Protein Degradation

Proteolysis is the breakdown of protein into amino acids. 8

Occurs in catabolism/negative nitrogen balance. 8

Short Term Interventions

Is a HP diet more effective in the short term than a HC diet?

Short Term Intervention 1

In 1994, Piatti et al conducted a study to compare the effects of a high protein diet (800kcal: 45% protein, 26% polysaccharide CHO, 9% monosaccharide and disaccharide CHO, 20% fat) and the effects of a high carbohydrate diet (45% polysaccharide CHO, 15% monosaccharide and disaccharide CHO, 20% protein, 20% fat) on body composition during a hypocaloric diet over twenty one days. 11

25 glucose-tolerant obese women were split up into two groups: HP group mean age 39±3 years and HC group mean age 41±4 years. 11

Short Term Intervention Results 1 The HP and HC groups both had similar

losses in body weight. 11

Fat free mass remained unchanged after the HP diet and was significantly decreased with the HC diet. 11

HP showed improved glucose tolerance.11

Proteolysis was suppressed in subjects consuming 1.5 g protein/kg ideal body weight. 11

Short Term Intervention 2

Farnsworth et all conducted a study to determine the effects of a HP energy restricted diet on body composition, glycemic control, and lipid concentrations in obese hyperinsulinemic men and women over 16 weeks. 4

HP Diet: (30% protein, 40% carbohydrates, and 30% fat) 4

SP Diet: (15% protein, 55% carbohydrate, and 30% fat) 4

Short Term Intervention Results 2 After 16 weeks, women lost significantly

less lean mass with the HP than with the SP diet. 4

Researchers noted women may have maintained more FFM than men due to a higher protein intake. 4

Women: 1.4 g or protein/kg ideal weightMen: 1.1 g of protein/kg ideal weight

Intervention 1 vs. Intervention 2

Intervention 1 found a protein intake of 1.5 g/ ideal body weight maintained nitrogen balance.

Intervention 2 found that men consuming 1.1 g/ kg ideal body weight lost more FFM compared to women who consumed 1.4g/ kg ideal body weight.

This is important to note because it shows a higher protein intake may be necessary to maintain FFM.

Long Term Intervention Are high protein

diets still effective when used long term?

Long Term Intervention Results

Wycherley et al found the HC and HP groups both had similar weight loss after one year. 15

HP lost less FFM than the HC group after one year.15

Exercise and High Protein Intakes Layman et al found the

HP plus Exercise group lost the most body fat and least amount of lean mass compared to the HC group and the HC plus Exercise group. 6

HP group: 1.5 g pro/kg Exercise: 5 days

walking and 2 resistance training days

Why was the high protein diet successful? Satiety TEF Hormone/biomarker improvements Preservation of FFM

Satiety Patients on a HP low calorie diet report a

higher level of satiety than patients on a HC low calorie diet. 13

Leidy et al found satiety was better preserved in subjects consuming a HP diet. 7

Increased satiety may result in increased adherence to a weight loss program.

Thermal Effect of Protein

High protein diets increase thermogenesis and 24 hour energy expenditure. (Hwalla Baba)

HP diet resulted in a 12% increase in energy expenditure when compared to a HC isoenergetic diet. (Hwalla Baba)

Improved Glucose Tolerance

Baba et al performed a dietary intervention on obese hyper-insulinemic subjects. 2

Fasting insulin levels were lowered to within normal ranges only in the HP diet group. 2

Importance of Maintaining FFM

Weight loss is the goal of a low calorie/hypocaloric diet.

A diet that can promote weight loss and improve body composition may be more conducive to long term health.

FFM “costs” calories and adds to the daily energy expenditure. 12

High Protein Diet Concerns

Bone demineralization?

Renal damage?

Bone Demineralization

No change in urinary calcium excretion or bone-turnover markers after 16 week high protein diet intervention. 4

Calcium excretion and bone density did not change after 64 week high protein diet intervention. 3

Long Term Renal Concerns

Brenner Hypothesis: increases in glomular filtration may cause kidney damage. 8

Azotemia is increased serum nitrogen after a high protein meal. 8

Increases in serum nitrogen causes an increase in glomular filtration. 8

Can a high protein intake cause renal damage?

Friedman et al found that a HP intake did have a modest effect on GFR. 5

However, the researchers concluded a HP diet does not fully explain the dramatic increases in glomular filtration rate and proteinuria in obese populations. 5

Long Term Outlook Is it logical to extrapolate data from clinical

populations with renal disease and apply those same dietary practices to healthy populations?

Martin et al believe these studies should not be used as dietary recommendations for healthy populations 9

No studies linking high protein diets as the cause of kidney disease.

Studies looked at the interaction between renal function in the diseased state and protein intake.

Future Considerations: Leucine

Leucine has been shown to inhibit protein degradation in the absence of increased insulin. 1

Leucine may regulate oxidative use of glucose by skeletal muscle through stimulation of glucose recycling via the glucose-alanine cycle. 1

If these responses can mitigate a protein sparing effect during low calorie intakes, Leucine may have a place in weight loss programs in the future. 10

Discussion Norton et al postulate that sufficient protein and

leucine intake has a greater effect on preventing protein degradation than the insulin response from carbohydrates.10

More research is warranted to determine if the timing of protein intake, quality of protein, and the timing of specific amino acids has an effect on body composition during low calorie diets.

Summary Each study concluded that the HP diet

was more effective for FFM maintenance than the HC diet.

The HP diet prevented patients in each study from dropping into a negative nitrogen balance.

Recommended protein intake during a low calorie/hypocaloric is 1.5 g of protein/ kg of ideal body weight. 11

Summary Continued Both clinical and athletic populations

may benefit from this research. Athletes involved in sports with weight

classes may want to consider increasing their protein intake during weight cutting periods in an effort to maintain FFM.

References1. Anthony, J. C., T. G. Anthony, D. K. Layman. 1999. Leucine supplementation

enhances skeletal muscle recovery in rats following exercise. J Nutr 129 (6) (June): 1102-6.

2. Baba NH, Sawaya S, Torbay N, Habbal Z, Azar S, Hashim SA. High protein vs high carbohydrate hypoenergetic diet for the treatment of obese hyperinsulinemic subjects. Int J Obes Relat Metab Disord. 1999;23:1202-1206.

3. Clifton PM, Keogh JB, Noakes M. Long-term effects of a high-protein weight-loss diet. The American Journal of Clinical Nutrition 2008; 87 (1): 23-9.

4. Farnsworth E., Luscombe N.D., Noakes, M., Wittert, G., Argyiou,and Clifton, P.M. Effect of a high-protein, energy-restricted diet on body composition, glycemic control, and lipid concentrations in overweight and obese hyperinsulinemic men and women Am J Clin Nutr 2003 78: 1 31-39. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12816768.

5. Friedman, A., Yu, Z., Juliar, B., Nguyen, J., Strother, M., Quinney, S., & ... Moe, S. (2010). Independent influence of dietary protein on markers of kidney function and disease in obesity. Kidney International, 78(7), 693-697. doi:10.1038/ki.2010.184.

6. Layman DK, Evans E, Baum JI, Seyler JE, Erickson DJ, Boileau RA. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. 2005;135:1903–10

References7. Leidy, H.J., Carnell, N.S., Mattes, R.D., and Campbell, W.W. Higher Protein

Intake Preserves Lean Mass and Satiety with Weight Loss in Pre-Obese and Obese Women. OBESITY, Vol. 15 No. 2. February 2007; 421-429.

8. Lowery, L. M. (2012). Dietary protein and resistance training. (1st ed., pp. 4-5, 18, 26-27). Boca Raton, FL: CRC Press Taylor & Francis Group.

9. Martin WF, Armstrong LE, Rodriguez NR. Dietary protein intake and renal function. Nutrition & Metabolism. 2005;2:25.

10. Norton, L. E., D. K. Laymen, P. Bunpo et al. 2009. The leucine content of a complete meal directs peak activation but not duration of skeletal muscle protein synthesis and mammalian target of rapamycin signaling in rats. J Nutr 139 (6) (June): 1103-9.

11. Piatti PM, Monti F, Fermo I, Baruffaldi L, Nasser R, Santambrogio G, Librenti MC, Galli-Kienle M, Pontiroli AE, and Pozza G. Hypocaloric high-protein diet improves glucose oxidation and spares lean body mass: comparison to hypocaloric highcarbohydrate diet. Metabolism 43: 1481–1487, 1994. Retrieved from Georgia Southern University Interlibrary Loan

12. Webb P. Energy expenditure and fat-free mass in men and women. Am J Clin Nutr. 1981;34:1816–1826

References13. Weigle, D. S., Breen, P. A., & Matthys, C. C. A high-protein diet induces sustained

reductions in appetite, ad libitum caloric intake, and body weight dispite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am Journal of Clinical Nutrition 2005; 82(1), 41-48. Retrieved from http://ajcn.nutrition.org/content/82/1/41.full

14. Williams, M. H. (2007). Nutrition for health, fitness, & sport. (Eighth Edition ed., p. 198). New York, NY: McGraw-Hill.

15. Wycherley, T. P., G. D. Brinkworth, P. M. Clifton, and M. Noakes. "Comparison of the Effects of 52 Weeks Weight Loss with Either a High-protein or High-carbohydrate Diet on Body Composition and Cardiometabolic Risk Factors in Overweight and Obese Males." Nutrition and Diabetes 2012 Aug 2.