Low Carb Diets Result In More Initial Weight Loss Compared to Low Fat and Mediterranean Diets

by Dr Sam Girgis on October 4, 2012

There has been a steady and dramatic increase in the number of people afflicted with obesity throughout the world.  The obesity epidemic has continued at a steady rate despite recent public health campaigns.  There are several diets that can help with weight loss.   Finding a diet that allows the initial weight loss and then permits good weight maintenance will be a key in fighting the obesity epidemic.  This is because many dieters can lose weight initially, but many regain the weight that is lost.  Part of the problem that dieters have with keeping the weight off is that many diets are too restrictive while others are not maintainable on a long term basis.  There are several diets that are currently used for weight loss such as the low carb diet (Atkins, Paleo), Mediterranean diet, and low fat diet.  It has been found that low carb diets allow for the most weight loss initially, but some weight is regained with these diets on a long term basis.

Researchers, led by Dr. Iris Shai from Ben-Gurion University, have found that low carbohydrate diets cause the most initial weight loss and result in improved lipid parameters.  The results of their study were published online in the New England Journal of Medicine.  The researchers conducted a 2 year trial involving 322 moderately obese individuals that were randomly assigned to one of three diets: low-fat, restricted-calorie; Mediterranean, restricted-calorie; or low-carbohydrate, non–restricted-calorie.  It was found that the mean weight loss was 2.9 kg for the low-fat group, 4.4 kg for the Mediterranean-diet group, and 4.7 kg for the low-carbohydrate group.  The researchers also found that the relative reduction in the ratio of total cholesterol to high-density lipoprotein cholesterol was 20% in the low-carbohydrate group and 12% in the low-fat group.

The authors wrote, “In this 2-year dietary-intervention study, we found that the Mediterranean and low-carbohydrate diets are effective alternatives to the low-fat diet for weight loss and appear to be just as safe as the low-fat diet. In addition to producing weight loss in this moderately obese group of participants, the low-carbohydrate and Mediterranean diets had some beneficial metabolic effects, a result suggesting that these dietary strategies might be considered in clinical practice and that diets might be individualized according to personal preferences and metabolic needs”.

The authors concluded, “Mediterranean and low-carbohydrate diets may be effective alternatives to low-fat diets. The more favorable effects on lipids (with the low carbohydrate diet) and on glycemic control (with the Mediterranean diet) suggest that personal preferences and metabolic considerations might inform individualized tailoring of dietary interventions”.

In a recent follow up letter to the New England Journal of Medicine, after the study participants were followed for an additional 4 years, it was commented:

“During this follow-up period, participants had regained 2.7 kg of weight lost in the low-fat group, 1.4 kg in the Mediterranean group, and 4.1 kg in the low-carbohydrate group.  For the entire 6-year period, the total weight loss was 0.6 kg in the low fat group, 3.1 kg in the Mediterranean group, and 1.7 kg in the low carbohydrate group… a 2-year workplace intervention trial involving healthy dietary changes had long lasting, favorable post intervention effects, particularly among participants receiving the Mediterraneanand low-carbohydrate diets, despite a partial regain of weight”.

This study shows that the low carb diet is the most effective for losing weight initially and resulted in the most weight loss after the first 2 years of the study.  Although, after continued follow up for an additional 4 years, the low carb dieters regained the most weight but still had significant weight loss.  Low carb diets are more difficult to adhere to compared to the Mediterranean diet because carbohydrates are difficult to avoid on a long term basis.  The most likely explanation for the regaining of weight in the additional 4 years of follow up is that compliance with the low carb diet was low.  It would be interesting see how much weight gain there was among those low carb dieters who were completely compliant with the low carb diet.  My suspicion is that those who were 100% compliant with the low carb diet did not regain any weight during the additional 4 years of follow up.

 

References:

Iris Shai et al. “Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat DietN. Engl. J. Med 2008; 359:229-241 published July 17, 2008 doi: 10.1056/NEJMoa0708681

Dan Schwarzfuchs et al. “Four-Year Follow-up after Two-Year Dietary InterventionsN. Engl. J. Med. 2012; 367:1373-1374 published October 4, 2012 doi: 10.1056/NEJMc1204792

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