Carl R. Darnall Army Medical Center - Health Library

Low-carbohydrate Diet Does Not Appear Any More Effective Than Low-fat Diet for Weight Loss in Severely Obese Adolescents

As in adults, overweight and obesity rates are climbing in children and adolescents. Most often weight gain is the result of an imbalance between the amount of calories burned by the body and the amount of calories consumed through food. A dietary approach is to increase the amount of daily proteins and decrease daily carbohydrates. But these diets have been shown to be at least as effective as low-fat diets in adults.

Researchers from University of Colorado examined the benefits of a high-protein, low-carbohydrate diet compared to a more traditional low-fat diet in severely obese adolescents. The study, published in the Journal of Pediatrics, found that there was similar weight loss between the two diet options.

About the Study

The randomized trial included 46 adolescents with severe obesity. The adolescents were assigned to one of two diet options for 13 weeks. The high-protein/low-carbohydrate diet limited carbohydrates to 20 grams/day. The low-fat diet aimed for daily fat intake at 30% of calories. The participants had significant difference in protein, carbohydrate, and fat intake.

Of the patients who continued on either diet, 30% lost at least 10% of their body weight. There was no significant difference between groups in the number of people that lost 10% of their weight. After 24 weeks, patients who followed the high-protein diet still had significant weight loss (average -14 pounds/6.31 kg), but patients on the low-fat diet no longer had significant weight loss (average -3 pounds/1.41 kg).

However, neither group continued to have significant weight loss after 36 weeks (meaning those who had lost weight had regained weight).

There was no significant difference between diets in post-meal hunger, fullness, or nausea. There were no serious adverse events or complaints with either diet option but 28% did not complete the trial. All participants were also given an exercise program that included at least 30 minutes of daily moderately vigorous physical activity.

How Does This Affect You? ^

There were some limitations with this study that may decrease the reliability of the results. First, there were few participants included in the trial. A larger number of participants increases the reliability of results. There was also a high number of participants who did not complete the trial. Dropouts not only decrease reliability of the results but also demonstrate a general problem with compliance to the diet that may be seen outside of a trial setting. The study also had a fairly short-term follow-up. Successful weight-loss programs need a long-term follow-up to evaluate weight-loss goals and maintenance.

The high dropout rate and loss of effectiveness demonstrate a common problem with diets like these. Restrictive diets are difficult to maintain long term. Weight loss is a good goal but fairly useless without the ability to maintain that weight loss. Keep in mind that changes you make to your diet to help you lose weight need to be maintained for a lifetime. Start with your current meal plan and make gradual changes, which you can live with, to help you reach and maintain your goal.


American Dietetic Association

American Heart Association


Krebs NF, Gao D, Gralla J, Collins JS, Johnson SL. Efficacy and safety of a high-protein, low-carbohydrate diet for weight loss in severely obese adolescents.J Pediatr. 2010 Aug;157(2):252-8.

Last reviewed May 2011 by Brian P. Randall, MD