This study is an open-label randomized controlled trial; therefore, participants and researchers will be aware of the assigned intervention type. However, to maintain allocation concealment, a stratified block randomization method with Sequentially Numbered, Opaque, Sealed Envelopes (SNOSE) will be used.
The study strata include four subgroups: 1) obese girls, 2) overweight girls, 3) obese boys, and 4) overweight boys. Within each stratum, participants will be allocated to intervention groups A and B in a 1:1 ratio. The block size is fixed at 4, such that in each block, 2 participants are assigned to one group and 2 to the other group. Random sequences will be generated separately for each stratum using SAS software version 9.4. These sequences will then be recorded on cards, and each card will be placed inside an opaque envelope. The envelopes will be prepared in advance, completely opaque, sealed, and non-transparent from the outside, with only the sequence number written on the outer surface. After placing the card inside, the envelope flaps will be glued and sealed to prevent any view of the contents. The envelopes will be kept in a box based on sequential numbering. Upon enrollment of each eligible participant, the envelope corresponding to the order of entry will be opened, and the allocated group will be revealed. In this way, prediction or manipulation of the allocation process will not be possible.