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Diets with High or Low Protein Content and Glycemic Index for Weight-Loss

Maintenance

Larsen T et al.

N Engl J Med 2010; 363: 2102-2113

Page 1 Larsen T et al. N Eng J Med 2010; 363: 2102-2113

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Pronutritionist’s background

• There is a constant dispute if macronutrient content of diet is a major determinant of success in weight loss, or not

• Diet low in carbohydrates and high in fat and protein have proved to be effective in weight loss.

• It is speculated that protein rich diet enhances satiety and thermogenesis and may prevent wasting of muscles during weight loss (Halton & Hu 2004)

• However, a long term trial could not confirm the assumed benefits of high protein diet in weight loss (Sacks et al 2009)

• Low glycemic index diet may produce gastrointestinal anorectic hormones via receptors that bind short chain fatty acids, the end products of fermentable carbohydrates, and possibly improve satiety (Hord & Frost 2010)

Larsen T et al. N Eng J Med 2010; 363: 2102-2113 www.pronutritionist.net

Methods (1/2)• a randomized dietary-intervention study

• n = 773 (entered the weight-maintenance phase)– BMI 27 – 47

• Phase 1: 8-week low-calorie-diet period– 800 kcal per day (Modifast products)– 400 g vegetables/d was allowed – total energy intake with vegetables and Modifast

800-1000 kcal

• Phase 2: weight-maintenance – randomization to one of five maintenance diets– duration 26 weeks

Page 3 Larsen T et al. N Eng J Med 2010; 363: 2102-2113 www.pronutritionist.net

Methods (2/2)• Five maintenance diets were:

– a diet low in protein (13 E%) with a low glycemic index

– a diet low in protein (13 E%) with a high glycemic index

– a diet high in protein (25 E%) with a low glycemic index

– a diet high in protein (25 E%) with a high glycemic index

– a control diet (followed dietary guidelines in each participating country)

• All diets were designed to have a fat content of 25-30 E%

• There was no restrictions on energy intake– in order to test the ability of the diets to regulate appetite and

body weight

• Dietary intake was followed by 3 day food diaries

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Results (1/6)

• The mean initial weight loss with the low-calorie diet was 11 kg

• Mean weight regain during the maintenance period was 560 g. Only the participants assigned to the diet that was low in protein with a high glycemic index had significant weight regain (1.67 kg)

• In high protein low GI diet participants lost -0,4 kg during the follow up

• The weight increase during the maintenance period was – 930 g higher in the low-protein groups than in the high-

protein groups (p = 0.003)

– 950 g higher in the high-glycemic-index groups than in the low-glycemic-index groups (p = 0.003)

• No differences in satiety were observedwww.pronutritionist.netLarsen T et al. N Eng J Med 2010; 363: 2102-2113Page 5

Results (2/6): changes in body weight and waist circumference

www.pronutritionist.netLarsen T et al. N Eng J Med 2010; 363: 2102-2113Page 6

Kg/cm

Results (3/6): drop-out rates at 26 weeks

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*) More drop outs in low protein high GI diet than in either all low GI or all high protein diets (P = 0.02 and P = 0.01)

Results (4/6)

• Achieved difference in protein content was 5.4 percentage points between the high-protein and the low-protein groups– targeted difference was 12 E% (13 E% vs. 25 E%)

• Achieved difference in glycemic index was 4.7 glycemic-index units between the low-glycemic-index and the high-glycemic-index groups– targeted difference was 15 glycemic-index units

www.pronutritionist.netLarsen T et al. N Eng J Med 2010; 363: 2102-2113Page 8

Results (5/6): Dietary intake at week 26

Low proteinLow GI

Low protein High GI

High protein Low GI

High protein High GI

Control diet

Energy (kcal/d) 1673 1826 1753 1673 1716

Carbohydrates (E%)

50.8 50.9 44.6 44.7 46.4

Total fat (E%) 29.8 30.9 32 31.2 33.7

Protein (E%) 18.2 16.7 21.7 22.6 18.7

Fiber (g/d) 21 20.3 21.4 19 19.6

Glycemic index 56.2 61.6 56.5 61.4 59.4

Glycemic load (g/d)

121 137.9 108.9 113.1 117.6

www.pronutritionist.netLarsen T et al. N Eng J Med 2010; 363: 2102-2113Page 9

Low proteinLow GI

Low protein High GI

High protein Low GI

High protein High GI

Control diet

Protein (in grams) 76 76 95 95 80

Results (6/6): Changes in fat and fat free mass from 0 to week 26

www.pronutritionist.netLarsen T et al. N Eng J Med 2010; 363: 2102-2113Page 10

Low proteinLow GI

Low protein High GI

High protein Low GI

High protein High GI

Control diet

Protein (in grams) 76 76 95 95 80

Changes in body composition are not statistically significant

kg

Pronutritionist’s discussion 1/4

• In this trial, the achieved dietary changes were again far from targeted

• In protein intake, the targeted difference at 1800 kcal level was 54 grams but the achieved difference was circa 20 grams ( 76 vs. 95 grams)

• However, the achieved level of protein intake may be more feasible in real life and therefore the results may have clinical high relevance

• Protein-low GI diet did not improve self-reported satiety which is a bit against expectations. This may be a function of less than expected differences in diets

• High protein diet in the trial contained same amount of protein as typical Western diet at level of circa 2 200 kcal/day

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Pronutritionist’s discussion 2/4

• Authors conclude “ … a diet that was moderately high in protein content and slightly reduced in glycemic index…appears to be ideal for preventing weight gain” . Why do the authors not refer to a longer term trial which did not show significantly improved weight loss results on a diet rich protein (Sacks et al 2009) ?

• As a diet for weight maintenance is expected to be life long, the effects of high protein diet on vascular health require attention. Interestingly, the authors do not point out this either. This argument has been one key argument against low carbohydrate diets

• Given the above, the effects of protein rich diet need to confirmed in long term trials (several years) to clarify the effects of high (animal) protein intake on vascular health

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Pronutritionist’s discussion 3/4

• Achieved results were reached by the exclusive interplay of protein and carbohydrate changes while fat intake was kept constant. According to the authors, this further underlines the importance of lowering glycemic load

• Authors do not ponder the mechanisms how low-GI-diets may induce weigh loss or maintenance. Hord & Frost 2010 have suggested that indigestible carbohydrates may trigger release of anorectic gastrointestinal compounds via specific short chain fatty acid receptors

• In a sub study of shop centers (Danish and Dutch centers) where foods were provided for free, high protein diet resulted in 3,7 kg greater weight loss compared to low protein diet. This further strengthens the observed effects

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Pronutritionist’s discussion 4/4

• There were no differences in body compositions between the groups. Muscle mass seemed to be preserved similarly. This is a bit contrary to what is commonly believed. In the initial weight loss period, all groups lost comparable shares of fat and fat free mass

• In this rather short term trial (26 weeks), moderately high protein and low GI diet improved maintenance of the diet. High protein diets (both of them) resulted in 1 kilo smaller weight gain, and so did both low GI diets. Low protein high GI diet was the only diet that induced significant weight gain (1,7 kg)

• This study further underlines the importance of protein in maintaining healthy weight but leaves many questions open

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