Nowadays, obesity is a major problem in societies globally which not only causes complications and disorders in physiologic health of obese persons, but also affects psychologic health and self-confidence adversely. In this research, we intended to compare cognitiveexecutive functions of the frontal lobe of the brain and lifestyle self-efficacy in persons with different body mass indices (BMI). Threehundred subjects with different BMI values were recruited via convenience sampling method. The questionnaires used included the Wisconsin Card Sorting Test, and the questionnaires for executive function disorder, lifestyle self-efficacy, and the general health. For data analysis, descriptive indices (mean, frequency) were used and for inferential indices, analysis of variance (ANOVA) was applied. The results showed that there is significant (P= 0.05) difference regarding attention shifting between persons with different BMI values. In subjects with different BMI values, cognitive functions are different, and reduced cognitive function was higher in those with higher BMI. Also, lifestyle self-efficacy was lower significantly (P = 0.05) in obese subjects compared to those with normal weight. Persons with different BMI values had different cognitive functions. Key words: Cognitive-executive function, the frontal lobe of the brain, body mass index (BMI), lifestyle self-efficacy