Service men and women returning from deployment are significantly more likely to develop asthma and severe respiratory symptoms from airway obstruction. Why this happens is not well known, but exposure to diesel, burn pits, biomass smoke, and sandstorms are thought to play a role. Ultimately, patients with deployment related asthma develop a complex airway disease that does not respond well to standard asthma medications. Therefore, it is imperative that safe and affordable treatments that could improve quality of life and symptoms are studied. It has been previously shown that adult patients with poorly controlled asthma have an abnormal regulation of an amino acid called L-arginine and airway nitric oxide (FeNO), a gaseous molecule normally produced in the airways of healthy people. In healthy people, nitric oxide is present in amounts that help keep the airways open. However, in some patients with asthma, nitric oxide and L-arginine are often low. The investigators' preliminary data in obese asthmatics show that L-citrulline, which is an amino acid that can be metabolized into L-arginine, improved lung function and asthma control, while increasing the levels of FeNO. This is potentially shifting the paradigm in how investigators think of asthma management, as rising FeNO is often thought of being a bad sign. Based on this, the study investigators hypothesize that an L-citrulline-based drug strategy will normalize nitric oxide metabolism, suppress oxidative inflammatory responses and improve airway function in obese patients with asthma. The study proposal presents a clinical trial approach to treat deployment related asthma patients using L-citrulline as an add-on therapy to improve asthma control. If this confirms the investigators' previous study results, the investigators will be in route for developing the only precision-based therapy available to treat this asthma phenotype. These study results will potentially show that L-citrulline is a safe, tolerable medication that can make a significant impact on the respiratory health of a large segment of our active and veteran population at a reasonable cost.