BACKGROUND: Behavioral interventions focusing on exercise and healthy diet improve asthma control in obese patients with asthma, but whether these interventions can lead to improvements in nonobese patients remains unclear. OBJECTIVES: In a randomized, controlled parallel-group design, we studied the effects of an 8-week intervention of either exercise (high-intensity interval training), diet (high protein/low glycemic index), or a combination of the 2, on asthma control and clinical outcomes in nonobese patients with asthma. METHODS: Nonobese adult patients with asthma (n = 149) were randomized to 1 of 4 groups: an exercise group, a diet group, an exercise + diet group, or a control group. Outcomes included Asthma Control Questionnaire (ACQ) score, asthma-related quality-of-life (Asthma-Related Quality-of-Life Questionnaire [AQLQ]) score, inflammatory cell counts in induced sputum, FEV RESULTS: A total of 125 patients completed the study and were included in the data analysis. Patients in the exercise + diet group improved the ACQ score from 1.9 ± 0.7 to 1.0 ± 0.7 and the AQLQ score from 5.2 ± 0.8 to 6.2 ± 0.7, which was statistically significant when compared with changes in the control group (P < .05 and <.01, respectively). The exercise group and the diet group did not improve either the ACQ score or the AQLQ score significantly compared with the control group and there were no significant changes in sputum cell counts, FEV CONCLUSIONS: The combination of exercise and diet improves asthma control in nonobese patients, but does not affect AHR or airway inflammation.