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.