To the Editor—
Several studies involving physical activity, dietary or combined
strategies have failed to show significant favorable effects in body mass
index (BMI) or body fat percentage after the intervention was over.(1)
However various studies have shown that multidisciplinary interventions
during childhood led to changes in dietary habits, nutrition knowledge,
increased fitness and physical activity levels.(2) The short and long term
benefits of a combined dietary-behavioral-physical activity intervention
program reported by Dan Nemet et al,(3) were promising. However, we
observed some limitations in this study.
1. The sample size was small when compared to other studies that had
similar interventions. The authors mentioned that they arrived at this
number based on 90% power. However they did not mention the percentage of
weight loss or decrease in BMI that was considered ‘significant’ (the
‘effect’ size) to get the minimum number of subjects.
2. Only 66% of the subjects in the intervention could be followed-up
at 12 months. With no additional information provided about the
characteristics of those who did not complete the study, we are left
wondering whether those who were least successful under the treatment were
the most likely to have dropped. That would leave only the successful
completers in the final analysis, hence skewing the results.
3. Did not account for the variability in daily diet. The 2-day
record might not be accurate if it includes special days like holidays,
festivals, parties or sickness.
4. It seems they took the same group of subjects for analysis at the
beginning of the study to compare with the parameters at 3 months as noted
in Tables 1, 2 and 3. However, the characteristics of the subjects at
beginning in Table 4 are different from the characteristics mentioned in
Table 1. The authors did not specify if they excluded the drop-out
parameters in Table 4. The screen time (before) for the control group in
Table 2 should be 4.6±4.2, similar to Table 1.
5. Potential interviewer bias could be there because the researchers
knew about the subjects in both groups.
6. The results of the study could not be extrapolated for other
populations.
7. The authors compared 3 month intervention with 12 month
intervention done earlier in Fig 2. It is not clear whether the control
group for the 12 month intervention is a combination of studies or one of
these studies.
At the completion of 3 months, there were significant within-group
differences for weight, BMI and body fat percentage in the intervention
group (Fig 1). However, when measured at 12 months, these differences were
not existent (Table 5). The differences between the control and
intervention groups persisted at 12 months. As indicated by the authors, a
much longer follow-up is needed to know if the benefits exist. Further,
biochemical testing (e.g., LDL levels) as noted by Sothern et al (4) is
extremely important to see if there is any difference between the control
and intervention group during a multidisciplinary approach. Therefore we
suggest a larger sample study, “intention to treat” to account for drop
outs, and a more diverse group to allow for comparisons to other
populations.
References
1. Summerbell CD, Waters E, Edmunds LD, Kelly S, Brown T, Campbell
KJ. Interventions for preventing obesity in children. Cochrane Database
Syst Rev 2005(3):CD001871.
2. Sharma M. International school-based interventions for preventing
obesity in children. Obes Rev 2007; 8(2):155-67.
3. Nemet D, Barkan S, Epstein Y, Friedland O, Kowen G, Eliakim A.
Short- and long-term beneficial effects of a combined dietary-behavioral-
physical activity intervention for the treatment of childhood obesity.
Pediatrics 2005; 115(4):e443-9.
4. Sothern MS, Despinasse B, Brown R, Suskind RM, Udall JN Jr,
Blecker U. Lipid profiles of obese children and adolescents before and
after significant weight loss: differences according to sex. Southern
Medical Journal. 93(3):278-82, 2000 Mar.
Conflict of Interest:
None declared
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