Cortisol, CrossFit and Inflammation Health

Hello y'all, my girlfriend and I have been doing CrossFit for almost a year now. We've both really loved our coaches and the experience and we are up to 5+ classes per week Recently my girlfriend has been worried that the increased cortisol from metcon training may be affecting her hormones/thyroid, preventing her from losing weight and keeping her in a state of inflammation. Does anyone know about the connection between CrossFit and cortisol? Is this a valid concern for people with thyroid issues or are other factors more likely culprit? She's looking to cancel her membership to focus on muscle fatigue, weightlifting at a globo gym, will this help her reduce inflammation?