Wednesday, October 8, 2014

Low Carb Diet Trials: Iqbal, et al (2010)

 
Participants and Diets
 
144 people with obesity and T2D were randomly assigned to a low-carbohydrate or to a low fat diet.  The groups were similar at baseline except that the low carb group had more women and African Americans (who were well represented in this trial), whereas the low fat group had more people with high cholesterol.
 
Low Carb
Low Fat
30g of carbs.  Whole grains and high fibre carbs were encouraged
No restriction on fat and calories.  MUFA and PUFA were encouraged, SFA and TFA to be minimised
≤30% Total fat, <7% SFA
500 calorie deficit
Fruits and vegetables were encouraged
 
They described this trial as a low intensity intervention.  “Both diet groups were invited to attend separate weekly 2-h nutrition education classes for the first month. Thereafter, participants were provided sessions every 4 weeks for the duration of the study”
 
 
Low Carb
Low Fat
Pro:Fat:Carb
Δ Calories
Pro:Fat:Carb
Δ Calories
Baseline
19:40:40
0
18:39:43
0
6 Months
20:43:35
-201
21:37:42
-410
12 Months
20:36:40
-348
20:36:43
-516
24 Months
17:34:48
-397
18:34:47
-571
 
“There were no differences between groups in the amount of self-reported physical activity at any time point (P > 0.14).”
 
Results
 
Not unexpected from the poor adherence and lack of difference in dietary intake between the groups, both groups didn’t lose much weight and there were no significant differences between the groups.  Perhaps due to the poor weight loss overall, there was no correlation between number of sessions attended with weight loss.
 
 
 
There wasn’t much change in metabolic risk factors for CHD and no significant difference between groups or compared to baseline
 
  

“76 participants (52.8%) did not complete the 24-month study. A higher attrition rate was seen in the low-carbohydrate than in the low-fat condition (60.0% vs. 46.0%, respectively), but it was not statistically significant (P = 0.09).”

2 comments:

  1. "SFA to be minimised", so meat and dairy also minimised?

    Without full-fat meat and dairy, seems like a clownish test of low-carb diets, given that saturated fat has been exonerated: http://ajcn.nutrition.org/content/91/3/535

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    Replies
    1. By extension most likely.

      I fully agree, but it's not like this trial was a good test of either diet anyway given how poor the adherence was and that the macronutrient intake between the groups was very similar at 6, 12 and 24 months

      I am very much in agreement with you that SFA doesn't increase risk of CHD and that replacing SFA with PUFA doesn't reduce CHD

      http://www.stevenhamley.com.au/2013/11/the-evidence-against-saturated-fat.html
      http://www.stevenhamley.com.au/2014/02/the-diet-heart-hypothesis.html
      http://www.stevenhamley.com.au/2014/02/the-diet-heart-hypothesis-part-2.html
      http://www.stevenhamley.com.au/2014/02/the-diet-heart-hypothesis-part-3.html

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