Introduction: This study aimed to determine inefficiencies in current educational programs for promoting of healthy lifestyles and prevention of obesity from the perspective of adolescents and mothers. Materials and Methods: This was a qualitative study conducted based on a grounded theory approach. To collect data, 23 personal interviews and 12 semi-structured focus group discussions were conducted with overweight/obese adolescents and mothers who had at least one overweight/obese child. To maximize the variation of participants’ experiences with different socio-economic backgrounds, two demographically diverse areas from the north and south of Tehran were selected and followed with theoretical sampling. All the interviews and focus group discussions were audio recorded and transcribed verbatim. Data collection and analysis were done simultaneously, using the Strauss and Corbin analysis method. Results: In the current study, inefficient education was explored using two main themes including “Single dimensional curriculum of schools” and “Inefficient public education”. The single dimensional curriculum of schools was found to be characterized by “lesson-based curriculum” and “burdensome educational programs” and the inefficient public education was characterized by “inappropriate content”, “lack of comprehensive educational program”, “inapp­ropriate ways of messaging” and “contradictory messages”. Conclusions: Based on the findings of this study, “single dimensional curriculum of schools” and “Inefficient public education” were the main correlates of inefficient education in our society, which led to obesity-related behaviors and consequently excessive weight gain in Tehranian adolescents. The results of this study may be effective in prioritizing and designing health promotion programs aimed at promoting healthy lifestyles and prevention of obesity in children and adolescents.