Chronic Stress Lowers Metabolic Rate
When the stress response becomes stuck as result of long term stress, the ongoing of cortisol causes the body to release sugar into the blood stream from glycogen. Which then will causes insulin to rise.
Stress programs us for fat storage and contributes to insulin resistance. Also elevated Cortisol levels can cause the body to burn muscle tissue as fuel. Which leads to lower metabolic rate.
This is a great article on a solution to reduce stress to keep your cortisol levels down and increase your metabolic rate so you can burn fat not muscle.