High Protein Diets in Weight Reduction

Transcription

1 High Protein Diets in Weight Reduction Effects on fat mass, muscle mass and risk factors of the metabolic syndrome Donald K. Layman and Layne E. Norton Department of Food Science & Human Nutrition University of Illinois at Urbana-Champaign Urbana, Illinois USA

2 Goals for designing a high protein diet? How much protein? What is the purpose of more protein? Outcomes: ŁSatiety ŁThermogenesis 4Ø protein and nitrogen metabolism 4Ø protein turnover (a futile cycle) Łchanges in body composition 4Œ fat mass 4Ø muscle mass

3 Goals for designing a high protein diet? How much protein? What is the molecular mechanism? substrate concept = need for more essential amino acids limiting amino acid: lysine metabolic concept = signaling regulations unique signal: leucine

4 Leucine as a nutrient signal Insulin GLUT4 [AMP] IRS-1 PI3-K Akt/PKB AMPK cell membrane TSC1/TSC2 Rheb [leucine] p70s6k mtor eif4e-bp1 rps6 eif4e eif4g Protein synthesis

5 Serum responses to oral leucine doses Crozier et al. J. Nutr.. 135: 376, 2005

6 Threshold for eif4g - eif4e binding Crozier et al. J. Nutr.. 135: 376, 2005

7 Leucine regulation of muscle protein synthesis in a complete meal 20% of kcal from whey protein: breakfast meal 4 g diet (94 mg leu) Plasma Leucine (µmol/l) Plasma leucine B (gamma form + beta form) / total p70s6 kinase activation Time (minutes) Time (minutes) Norton et al. (submitted for publication)

8 Leucine regulation of muscle protein synthesis in a complete meal 20% of kcal from whey protein: breakfast meal 4 g diet (94 mg leu) Plasma leucine Muscle protein synthesis Plasma Leucine (µmol/l) Skeletal Muscle FSR (%/day) Time (minutes) Time (minutes) Norton et al. (submitted for publication)

9 Comparison of whey vs. wheat proteins for stimulation of muscle protein synthesis Plasm a Leu cine (µm ol/l) Plasma leucine Meal leu (mg) S keletal M uscle F S R (% /day) Muscle protein synthesis 50 0 Baseline 10% 20% 30% % calories from protein 0 Baseline 10% 20% 30% % calories from protein whey protein wheat protein Norton et al. (submitted for publication)

10 Comparison of whey vs. wheat proteins for stimulation of muscle protein synthesis Plasma Leucine p70s6 kinase activation A Plasm a Leu cine (µm ol/l) gamma form / total Baseline 10% 20% 30% % calories from protein 0.1 Baseline 10% 20% 30% % calories from protein Norton et al. (submitted for publication) whey protein wheat protein

11 Protein goals for adult weight loss 2.5 g of 3 meals/day 30 g of 3 meals/d ~ 1.5 g protein/kg body weight Diet key for adults is correcting BREAKFAST

12 High protein weight loss studies Study wk diet study, prepared meals Study wk study, diet and diet + exercise restricted menus, highly supervised Study month diet study, free-living subjectsweekly meeting with weigh-in and 3- day weighed food records

13 Overview of weight loss diets diets with: 1600 kcal/day PRO diet: protein (> 1.5 g/kg.d) carbohydrates (< 150 g/day) fat ~ 30% of kcals Diets as percent of energy intake: PRO group: 40% carbohydrates, 30% protein, 30% fat CHO group: 55% carbohydrates, 15% protein, 30% fat

14 Exercise Treatments no EX: < 100 min/wk of walking EX: > 210 min with 5 days/wk walking and 2 days resistance training Treatment Groups: (n = 12) PRO, PRO + Ex, CHO, CHO + EX

15 Changes in Body Weight and Composition Diet effects CHO Groups PRO Groups Body weight (kg) Fat mass (kg) Lean mass (kg) Exercise effects EX no EX Body weight (kg) Fat mass (kg) Lean mass (kg) Layman et al. J. Nutr.. 135: 1903, 2005 P < 0.05

16 Changes in Blood Lipids (mg/dl) Diet Effects CHO Groups PRO Groups total cholesterol LDL-C HDL-C TAG Exercise effects EX no EX Total cholesterol LDL-C HDL-C TAG P < 0.05

17 Muscles and adipose Akt after meal 80 skeletal muscle PRO = 30% of kcal CHO = 15% of kcal 80 adipose % phosphorylation of total % phosphorylation of total Fasted Time (min) 0 Fasted Time (min) PRO CHO

18 Outcomes with high protein, low Carb diets Body composition Metabolic Œ weight loss Ø loss of body fat Ø protein sparing Œ TG (VLDL) Ø HDL Ø glycemic control Metabolic Syndrome