The Journal of Pediatrics
Volume 157, Issue 2 , Pages 184-185, August 2010

New Safety Data on the High-Protein–Low-Carbohydrate Diet in Adolescents

  • Miriam Vos, MD, MSPH

      Affiliations

    • Corresponding Author InformationReprint requests: Miriam Vos, MD, MSPH, Assistant Professor of Pediatrics Emory University &Children's Healthcare of Atlanta, 2015 Uppergate Dr, NE, Atlanta, GA 30322.

Assistant Professor of Pediatrics, Emory University, Children's Healthcare of Atlanta, Atlanta, Georgia

published online 07 June 2010.

Article Outline

BMI, Body mass index, HDL, High-density lipid protein, HPLC, High-protein–low–carbohydrate, TG, Triglyceride

 

See related article, p 252

Because of the comorbidities and increased mortality associated with severe pediatric obesity,1 safe and effective medical treatments are sorely needed. Compared with the treatment of severe adult obesity, treatment of children who are obese requires attention to the effects on growth and a greater attention to sustainability. A high-protein–low-carbohydrate (HPLC) diet, also called the “protein-sparing modified fast” is one approach to treat severe obesity, but little safety and efficacy data exist in the pediatric population. In adults, hypocaloric low-carbohydrate diets and low-fat diets have been compared in a 2-year study and found to be equivalent in weight loss and patient satisfaction.2 In theory, low-carbohydrate diets could have specific benefits for patient satisfaction because the ketosis induced can suppress appetite. In addition, earlier research has shown that carbohydrates, and specifically fructose, are associated with lower high-density lipid protein (HDL) cholesterol levels and higher triglyceride (TG) and low-density lipoprotein cholesterol levels,3, 4, 5 a lipid profile associated with increased cardiovascular disease risk.4, 6, 7

In the randomized, controlled comparative effectiveness trial by Krebs et al, which appears in this issue of The Journal, a HPLC diet was compared with a calorie-restricted low-fat diet in 46 severely obese adolescents during 13 weeks.8 Follow-up measurements were obtained at 13, 24, and 36 weeks.8 Both groups were advised to participate in 30 minutes per day of vigorous physical activity, but activity levels were not quantified. After 13 weeks of the prescribed diet, adolescents in both groups had a significantly improved body mass index (BMI) Z score, but the improvement was greater in the HPLC group. There was no significant difference in reported total energy intake, although it appears that there was a trend toward decreased intake in the HPLC group. Growth was preserved in both groups, and no adverse cardiac and metabolic effects were found, demonstrating equal safety of both diets. Contrary to expectations, the adolescents in the HPLC did have a small loss in lean body mass (marginally significant) that was not seen in the low-fat group, casting doubt on the popular theory of a “protein-sparing” phenomenon. After 36 weeks, both the HPLC group and the low-fat group had similar improvement in BMI Z score.

Strengths of this study include the careful quantification of multiple body weight and fat measurements and the follow-up of the adolescents after the primary intervention period ended. After 36 weeks, the weights of the two groups were similar, suggesting that the short-term advantages of the HPLC diet are attenuated in time. This study provides much needed comparison of two diets that are commonly used in adolescents and refutes several of the common concerns about a high-protein low-fat diet. No adverse effect on lipids was found, despite the relatively increased fat consumption. In the HPLC group of subjects, a significant reduction in triglyceride levels was seen that was not present in the low-fat group. This fits with the known hypertriglyceridemic effect of high-carbohydrate diets and sugars and is particularly concerning for the long-term outcome of low-fat diet group. No reciprocal increase in HDL cholesterol level was found in the HPLC group, but in the low-fat (high-carbohydrate) diet, there was a small but significant decrease in HDL cholesterol level. The authors did not report the type of carbohydrates being consumed (sugars versus whole grains), but a decrease in HDL cholesterol level would be expected if the low-fat group had increased their added sugars.9

Even with this intensive intervention of carefully selected adolescents supported every two weeks, only approximately half the adolescents lost >5% of their baseline weight. This is typical of dietary and behavioral treatment of obesity10 and highlights how difficult it is to achieve clinically significant and sustainable weight loss, particularly in the severely obese subject. When the 18 subjects (of 51 subjects who were randomized) who dropped out were added, the “failure” rate would be even higher. The 2009 Cochrane review of pediatric obesity treatments reported that family-targeted behavioral lifestyle interventions with a dietary and physical activity component were successful in improving BMI,11 but this approach appears to be less successful in children who are severely obese.12 Although beyond the scope of this study, perhaps combining the HPLC diet with more defined physical activity and ongoing family-targeted behavioral support would lead to an improved success rate.

This study is an important addition to the evidence that a HPLC diet may be safely used, at least in the short-term, in the treatment of severely obese adolescents. Future studies will be needed to determine whether this type of diet will be more effective when combined with other interventions, whether it is safe and feasible to adhere to this diet for a longer period, and what the long-term sustainability of weight loss is for a HPLC diet in adolescents. When diets such as the HPLC are used in the clinical office or treatment program, it is also typically with greater visit frequency in the beginning and then less frequent follow-up after the first months or year. Thus, it will be important that trials such as this one have mechanisms (and are awarded funding) to collect long-term outcome information. It may be that one or the other of these diets is more sustainable—but unless that information is collected, we will have to continue to guess about long-term effects.

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References 

  1. Franks P, Hanson R, Knowler W, Sievers M, Bennett P, Looker H. Childhood obesity, other cardiovascular risk factors and premature death. N Engl J Med. 2010;362:485–493
  2. Sacks FM, Bray GA, Carey VJ, Smith SR, Ryan DH, Anton SD, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med. 2009;360:859–873
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  4. Stein O, Stein Y. Atheroprotective mechanisms of HDL. Atherosclerosis. 1999;144:285–301
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  6. Wilson PWF, Anderson KM, Castelli WP, Kannel WB. Twelve-year incidence of coronary heart disease in middle-aged adults during the era of hypertensive therapy: the Framingham offspring study. Am J Med. 1991;90:11–16
  7. Sacks FM. The role of high-density lipoprotein (HDL) cholesterol in the prevention and treatment of coronary heart disease: expert group recommendations. Am J Cardiol. 2002;90:139–143
  8. Krebs NF, Gao D, Gralla J, Collins J, Johnson S. Efficacy and safety of a high protein, low carbohydrate diet for weight loss in severely obese adolescents. J Pediatr. 2010;157:252–258
  9. Siri-Tarino P, Sun Q, Hu F, Krauss R. Saturated fat, carbohydrate and cardiovascular disease. Am J Clin Nutr. 2010;91:502–509
  10. Kamath C, Vickers K, Ehrlich A, McGovern L, Johnson J, Singhal V, et al. Behavioral interventions to prevent childhood obesity: A systematic review and metaanalyses of randomized trials J Clin Endocrinol Metab. 2008;93:4606–4615
  11. Oude Luttikhuis H, Baur L, Jansen H, Shrewsbury VA, O'Malley C, Stolk RP, et al. Interventions for treating obesity in children. Cochrane Database Syst Rev. 2009;(1):CD001872
  12. Levine MD, Ringham RM, Kalarchian MA, Wisniewski L, Marcus MD. Is family-based behavioral weight control appropriate for severe pediatric obesity?. Int J Eat Disord. 2001;30:318–328

 Supported by an NIH grant K23DK080953. M.V. is the author of “The No Diet Obesity Solution for Kids” published by the American Gastroenterology Society in 2009.

PII: S0022-3476(10)00317-3

doi:10.1016/j.jpeds.2010.04.017

Refers to article:

  • Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents , 22 March 2010

    Nancy F. Krebs, Dexiang Gao, Jane Gralla, Juliet S. Collins, Susan L. Johnson
    The Journal of Pediatrics August 2010 (Vol. 157, Issue 2, Pages 252-258)

The Journal of Pediatrics
Volume 157, Issue 2 , Pages 184-185, August 2010

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