March 12, 2011

080 Low-Carb vs. Low-Fat Diets [13 September 2010]

Despite their popularity, low carbohydrate diets continue to be denounced as dangerous and criticized for a lack of supporting research. Two studies this decade compared low carb and low fat diets with some surprising results.

A 2004 study followed 120 obese participants, randomly assigned to either a low carb or low fat diet, for 24 weeks. The low fat group were restricted in fat, dietary cholesterol and calories; the low carb group were limited to <20g carbs /day, allowed unlimited animal fat and protein, allowed 2 cups of salads and 1 cup of low carb vegetables, and given certain nutritional supplements. Both groups were given exercise recommendations. At 24 weeks the low carb group had lost an average of 12.9% of body weight and 9.4kg of fat compared with the low fat group loss of 6.7% and 4.8 kg. The low carb group had greater reductions in triglycerides and greater increase in HDL (“good cholesterol”). LDL (“bad cholesterol”) was not significantly different.

The March 2010 study compared similar diets over a 2 year period and more health factors were monitored. The longer period provided quite different results. At 3 and 6 months the low fat group had a greater reduction in LDL and the low carb group had a greater drop in triglycerides, but there was no difference in either at 12 and 24 months. HDL was significantly higher in the low carb group throughout the study. Blood pressure, glucose and insulin all improved in the low carb group only. There was no significant difference in weight loss between the two groups, and no difference in bone mineral density or body composition.

While inconclusive as to which approach is superior from the point of weight loss, to me the significance of these studies is that the predicted health threats of a low carb (and high fat/protein) diet did not materialize. In fact cardiovascular risk factors appear somewhat superior for the low carb diet. And for reasons explained in previous columns, those who have experienced a low carb diet know how easy and painless it can be to lose weight.

This article is intended for educational purposes only; for medical advice consult your licensed health practitioner.

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