You can use the PICO(T) to help develop your topic. The PICO(T) question is the process employed in Evidence Based Practice.
Below you can find resources that they can help to develop your topic:
Clinical question
Can motivational interviews be effective in reducing pediatric BMI?
Possible article:
Tucker, S. J., Ytterberg, K. L., Lenoch, L. M., Schmit, T. L., Mucha, D. I., Wooten, J. A., . . . Wahlen, K. J. M. (2013). Reducing pediatric overweight: Nurse-delivered motivational interviewing in primary care. Journal of Pediatric Nursing, 28(6), 536-547