Low Carb Diet Trials: Davis, et al (2009)

Comparative Study of the Effects of a 1-Year Dietary Intervention of a Low-Carbohydrate Diet Versus a Low-Fat Diet on Weight and Glycemic Control in Type 2 Diabetes

 

Participants and Diets

 

105 People aged > 18, with T2D for at least 6 months, BMI ≥ 25 and A1c 6-11% were randomly allocated to a low carb group or a low fat group.  In this trial, 82 of the participants were female and 67 were classified as black.  The groups were similar at baseline

 

Diet Group	Diet Advice
Low Carb	2 Week phase of 20-25g carbs, 5g carb increments each week
Low Fat	Fat gram goal (25% of total calories)

 

“At randomization, all participants received 45 min of individual dietary instruction by a registered dietitian and were given a specific gram allowance of carbohydrates or fat to achieve a 1-pound weight loss each week. Structured menus that provided meal choices and recipes were used for the first 2 weeks. After the first 2 weeks, participants were instructed on selecting foods that met their dietary goals without using the menus. During the 12-month study, participants had a total of six scheduled, 30-min visits with the dietitian for additional dietary counseling.”

 

“We provided participants with general recommendations to achieve 150 min of physical activity each week, but physical activity was not an emphasis of the study.”

 

Pro:Fat:Carb	Low Carb	Low Fat
Baseline	20:36:44	19:39:41
6 Months	23:43:34	21:31:48
12 Months	23:44:33	19:31:50

 

Reduction in Calories	Low Carb	Low Fat
6 Months	-331	-341
12 Months	-210	-53

 

Results

 

The LC group lost more weight and had better improvements in metabolic markers at 3 months (not sure if significant), but regained some of the weight loss and didn’t maintain those improvements at 12 months (see table 2)

 

 

		3 months	6 months	12 months
HbA1c (%)	Low Carb	−0.64	−0.29	−0.02
	Low Fat	−0.26	−0.15	0.24
Systolic blood pressure (mmHg)	Low Carb	−5.80	−0.78	2.00
	Low Fat	−0.98	−3.70	−1.80
Diasystolic blood pressure (mmHg)	Low Carb	−2.20	−0.93	−2.90
	Low Fat	−0.40	0.95	−2.20

 

Overall, there were no significant improvements in systolic blood pressure, diastolic blood pressure HbA1c and blood lipids in either group, except that the low carb group had a significant increase in HDL-C at both 6 and 12 months (see table 2)

 

There was no difference in the number of participants who completed the trial (44/50 (88%) in low fat group, 47/55 (85%) in low carb group).