• Diet versus diet and exercise in pediatric populations

    In this week’s JAMA Pediatrics, “Impact of Dietary and Exercise Interventions on Weight Change and Metabolic Outcomes in Obese Children and Adolescents“:

    Importance  Diet and exercise represent the mainstays of obesity treatment. No systematic review has been conducted comparing the effect of dietary and exercise intervention in reducing metabolic risks in overweight children.

    Objective  To compare the effects of diet-only intervention with those of diet plus exercise or exercise only on weight loss and metabolic risk reduction in overweight children.

    Evidence Review  English-language articles from 1975 to 2010 available from 7 databases were reviewed. One person searched the databases. Two independent reviewers assessed abstracts and articles against the following eligibility criteria: randomized controlled trials conducted in overweight and obese children aged 18 years or younger, comparing dietary intervention with a diet plus exercise program or an exercise-only program. Study quality was critically appraised by 2 reviewers using established criteria. The main outcome measures were body mass index, body fat percentage, lean body mass, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, fasting glucose, and fasting insulin.

    This was a systematic review and meta-analysis of interventions for weight loss and risk reduction on kids who are overweight. Mostly, they wanted to compare different combinations of diet and exercise in programs. I was going to summarize the finding for you, but an excellent editorial already did that (emphasis mine):

    The main findings of Ho et al are that diet-plus-exercise interventions had no beneficial effect over diet-only programs at reducing body mass index, and in fact, exercise programs that included resistance training showed an overall increase in body mass index with a decrease in percentage of body fat, presumably because of increased lean body mass. They found that diet-only interventions were associated with greater short-term improvements in triglyceride levels and long-term reductions in low-density lipoprotein cholesterol levels. Finally, they report that diet-plus-exercise interventions showed superior improvement to short-term fasting glucose, insulin, and high-density lipoprotein cholesterol levels compared with diet alone. Diet-only and diet-plus-exercise interventions showed various short-term benefits; however, these positive alterations were generally attenuated back to baseline measures at later follow-up.

    Every time I turn around, I see another campaign to get kids to get up and be active. I think that’s great. But dietary changes are absolutely necessary, too. We need to focus on those much more. It’s not as sexy, nor as fun, but it’s incredibly important.

    @aaronecarroll

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    • ” and in fact, exercise programs that included resistance training showed an overall increase in body mass index with a decrease in percentage of body fat, presumably because of increased lean body mass.”

      Hmm. Reading the above, I’d not be so quick to discount exercise.

      BMI is, as I understand it, intended as a proxy for percentage of body fat, which is presumably the thing that causes the problems for obese people. But this sure sounds like a case where BMI is telling us exactly the wrong thing.

    • Per our conversation earlier this week…I stand corrected.