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PEDIATRICS 06.18.2013
by Cole Petrochko
Staff Writer, MedPage Today
Diet and exercise together were more effective at dropping weight and improving metabolic profiles in overweight children compared with diet-only interventions, researchers found.
Short-term exercise and diet interventions showed greater improvements in high density lipoprotein (HDL) cholesterol, fasting glucose, and fasting insulin, according to Mandy Ho, MSc, RN, of the Children’s Hospital at Westmead in Australia, and colleagues.
Prior research has studied the effects of diet and exercise interventions in children on weight loss, but none have systematically reviewed the effects of the interventions separately, they wrote online in JAMA Pediatrics.
The researchers looked to analyze the effects of a diet-only intervention against the effects of a diet and exercise intervention on metabolic risk markers and weight loss in a systematic review of 15 short-term trials of overweight and obese children, ages 18 and younger.
Included studies measured body mass index (BMI), body fat percentage, lean body mass, HDL, low density lipoprotein (LDL), triglycerides, fasting glucose, and fasting insulin.
Interventions lasted from 6 weeks to 6 months and seven studies followed up with participants after the end of the intervention, though only one study followed up after more than a year following the study’s completion.
Dietary interventions included calorie restriction in nine studies, or the “Traffic Light Diet” that limited sugar and increased dietary fiber or offered dietary advice. Education included as little as one 15-minute DVD intervention to 10 weekly 2-hour nutrition sessions with a monthly telephone follow-up over 3 months.
Exercise interventions included a supervised training session in 13 studies, though the intensity and variety of these workouts differed between studies, such as aerobic exercises in eight studies and resistance training in four studies, and two studies that included both. All but one study required 70 or more minutes of exercise weekly, while one included 6 hours of in-school exercise weekly.
Compared with an altered diet alone, nine studies of a combined 519 participants showed no significant changes in BMI for diet-only versus diet plus aerobic interventions (P=0.21) or aerobic and resistance training interventions (P=0.59). However there were reductions in BMI and/or body fat percentage over 6 months in 12 of 14 studies.
Resistance training interventions for 20 to 60 minutes over 6 weeks were associated with a greater body fat percentage loss than diet alone. The authors reported that the opposite was seen in aerobic training versus diet alone, though they noted high heterogeneity. Body fat percentage loss was significantly greater in a diet plus exercise intervention than in diet alone in two studies.
Both intervention groups improved or maintained total cholesterol, LDL, and triglyceride levels as measured through six studies. Triglycerides were improved in the diet-only groups by a pooled 13.27 mg/dL (95% CI minus 23.89-minus 1.77).
Diet and exercise improved HDL levels more than diet alone by a pooled 3.86 mg/dL (95% CI 2.70 to 4.63); however, these differences were nonsignificant at 1-year follow-up.
Pooled differences in LDL favored diet-only by 5.41 mg/dL (95% CI minus 9.27-minus 1.16).
Fasting glucose and fasting insulin were both improved in the diet and exercise group versus diet alone by a pooled -2.16 mg/dL (95% CI minus 3.78-minus 0.72) and -2.75 muIU/mL (95% CI minus 4.50-minus 1.00), respectively.
Finally, participants who received a diet-only intervention saw improvements in triglyceride and LDL cholesterol levels.
The authors concluded that dietary interventions are “an essential component for managing childhood obesity” and that the review of different exercise interventions show which affect various metabolic risk factors.
An accompanying editorial by Tessa Crume, PhD, and Curtis Harrod, MPH, cautioned that effect sizes in the review may be inflated due to poor methodological rigor in individual studies, publication bias in the study search, and the unlikely event that a rigorously controlled trial’s outcomes would be duplicated in real-world clinical or public health settings.
Crume is from the University of Colorado in Denver and Harrod is from the same institution in Aurora, Co.
They added that other research has shown family-based interventions, rather than child-focused ones, may produce better outcomes, as parents serve as figures of “authority and role models for their children.”
The editorialists also noted that there was a relative lack of long-term impact in the studies.
The authors said their study was also limited by heterogeneity of included studies, short follow-up time, small sample sizes, and absent data on individual study participants.
The study was supported by the Dora Lush Postgraduate Scholarship, the Early Career Development Fellowship Grant, the Priority Research Centre in Physical Activity and Nutrition, the Career Development Fellowship from the Australian National Health and Medical Research Council, and the Joanna Briggs Institute.
The authors declared no other conflicts of interest.
The editorialists declared no conflicts of interest.
Primary Source
JAMA Pediatrics
Source Reference: Ho M, et al “Impact of dietary and exercise interventions on weight change and metabolic outcomes in obese children and adolescents” JAMA Pediatr 2013; DOI: 10.1001/jamapediatrics.2013.1453.
Secondary Source
JAMA Pediatrics
Source Reference: Crume TL, Harrod CS “Childhood obesity: Is there an effective treatment?” JAMA Pediatr 2013; DOI: 10.1001/jamapediatrics.2013.102.