Wednesday, November 12, 2014

Low fat vs low carb for weight loss

The Study
148 obese men and women were randomized to a low fat (<30% of calories) or a low carbohydrate diet (<40 grams per day) for 12 months. By the end of follow up, participants on the low carb diet lost significantly more weight (8 pounds), lost significantly more fat mass, had significantly lower total:HDL cholesterol ratios, had significantly lower triglycerides, and significantly higher HDL cholesterol. Annals of Internal Medicine 2014; 161:309-18.

Take Home Message
This study showed that a lower carb/moderate fat diet not only enhanced weight loss, but also improved risk factors for coronary heart disease. The design of this study was exceptional, with low drop-out rates and high compliance. The only problem I have is with the title: “Effects of low carbohydrate and low fat diets”. By the end of the study, the participants were not really following a traditional low carb diet.

When I think of a low carb diet, I think Atkins, with very little carbohydrate, tons of steak, bacon, cheese and very little fiber. However, the low carb diet in this study was quite different. By the end of the 12 months, the low carb dieters were not consuming the recommended 11% of calories as carbohydrate, but fully 34% of their calories were carbohydrate. They also had very similar amounts of fiber as the low fat group. Although they did include a bit more saturated fat than the low fat group, the majority of their fat consumption (about 70%) was healthy monounsaturated or polyunsaturated fat. Indeed, what they were consuming by the end of follow-up was much more of a Mediterranean diet than a low carb diet.  Either way, this is still a well-designed study showing that a low fat diet is not the way to go for weight loss or improved health.

 

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