Sunday, August 24, 2014

Low Carb Diet Trials: Gardner, et al (2007)

 
Participants and Diets
 
311 pre-menopausal women with a BMI between 27-40 and without T2D were randomised to one of four diet groups: Atkins, Zone, LEARN or Ornish.  The groups were similar at baseline.  They received weekly instruction for 2 months, then an additional 10-month follow-up.  85% to 89% of participants attended at least 75% of their assigned classes and was not different by diet group.  “Retention at 12 months was 88%, 77%, 76%, and 78% for the Atkins, Zone, LEARN, and Ornish groups, respectively, and was not significantly different among groups (P = .30)”
 
Diet Group
Diet Advice
Atkins
20g Carbs for 2-3 months, 50g thereafter
Zone
30P:30F:40C, calorie restriction
LEARN
55-60% Carbs, < 10% SFA, calorie restriction, exercise, behaviour modification strategies
Ornish
≤ 10% Fat
 
None of the groups achieved their targets (see Table 2 for more info):
 
Pro:Fat:Carb
Atkins
Zone
LEARN
Ornish
Baseline
17:36:46
16:36:47
17:33:48
16:35:48
2 Months
28:55:18
24:35:42
20:30:49
17:21:63
6 Months
22:47:30
20:36:44
18:31:48
18:28:53
12 Months
21:44:35
20:35:45
19:33:47
18:30:52
 
But they did all reduce calorie intake
 

Results
 
All groups lost weight.  The Atkins group lost more weight which was only significant compared to the Zone group at 12 months
 
 
The Atkins group also had slightly better metabolic markers at 12 months:
 
 
Atkins
Zone
LEARN
Ornish
BMI (kg/m2)
-1.65 a
-0.53 b
-0.92 a,b
-0.77 a,b
Body Fat %
-2.9
-1.3
-1
-1.5
Waist-Hip Ratio
-0.019
-0.013
-0.009
-0.012
LDL-C (mg/dl)
0.8
0
0.6
-3.8
HDL-C (mg/dl)
4.9 a
2.2 a,b
2.8 a,b
0.0 b
Triglycerides (mg/dl)
-29.3 a
-4.2 b
-14.6 a,b
-14.9 a,b
Non-HDL-C (mg/dl)
-5.1
-0.5
-4
-6.8
Insulin (µU/ml)
-1.8
-1.5
-1.8
-0.2
Glucose (mg/dl)
-1.8
-1.6
0.5
-0.8
Systolic Blood Pressure (mmHg)
-7.6 a
-3.3 b
-3.1 b
-1.9 b
Diastolic Blood Pressure (mmHg)
-4.4 a
-2.1 a,b
-2.2 a,b
-0.7 b
 
Interestingly, even though all groups maintained a reduction in calories for the whole 12 months and some weight loss, their total energy expenditure didn’t change at all, suggesting modest weight loss doesn’t necessarily cause ‘the starvation response’.
 
 
 
Atkins
Zone
LEARN
Ornish
EE
(kcal/kg)
Baseline
33.7
34.1
33.9
34.9
2 Months
34.6
34.5
34.8
34.7
6 Months
34.3
34.4
34.8
34.6
12 Months
34.8
35.4
35.6
35.8
Total EE
(kcal)
(calculated)
Baseline
2898
2864
2882
3001
2 Months
2827
2827
2864
2896
6 Months
2751
2822
2850
2897
12 Months
2838
2923
2936
3005
 

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