Being under stress causes a release of the hormone cortisol. Cortisol's functions include blood pressure regulation, glucose metabolism, blood sugar maintenance, and immune system support. During a stressful event this has positive effects including a higher pain threshold and a rush of energy. However, when your body is constantly producing an abnormally high amount of cortisol, it can disrupt your normal cortisol production and have a negative impact on your health.
Excess cortisol stimulates glucose production leading to a release of insulin. These internal activites result in an increase in appetite. Additionally, the excess glucose is converted to and stored as fat. Some studies have shown that excess cortisol not only increases fat storage, it can also effect where the fat is stored. Researchers believe that cortisol specifically leads to an increase of abdominal fat.
It is possible to keep excess cortisol in check with the proper nutrients, such as vitamin C. Studies have shown that supplementing with between 500mg and 1000mg of vitamin C daily can help reduce cortisol levels post-exercise compared with placebo. Additionally, as an anti-oxidant, vitamin C may be effective for reducing oxidative damage from free radicals produced when cortisol levels are high.