What processes occur in the body during a period of severe stress?

Can someone who knows this stuff please inform me on the processes that occur in the body during a period of severe stress. I have heard things like stress makes you gain weight, stress makes you lose muscle mass, stress causes increased blood sugar levels, stress causes the breakdown of protein in the body and increased fat storage. However, I am not exactly sure how many of these are true and am interested in finding out the real facts behind stress.

Stress is the body's reaction to any change that requires an adjustment or response. The body reacts to these changes with physical, mental, and emotional responses.

Stress is a normal part of life. Many events that happen to you and around you,and many things that you do yourself,put stress on your body. You can experience stress from your environment, your body, and your thoughts.

How does stress affect health?

The human body is designed to experience stress and react to it. Stress can be positive, keeping us alert and ready to avoid danger. Stress becomes negative when a person faces continuous challenges without relief or relaxation between challenges. As a result, the person becomes overworked, and stress-related tension builds.

Stress that continues without relief can lead to a condition called distress,a negative stress reaction. Distress can lead to physical symptoms including headaches, upset stomach, elevated blood pressure, chest pain, and problems sleeping. Research suggests that stress also can bring on or worsen certain symptoms or diseases.

Stress also becomes harmful when people use alcohol, tobacco, or drugs to try to relieve their stress. Unfortunately, instead of relieving the stress and returning the body to a relaxed state, these substances tend to keep the body in a stressed state and cause more problems.

It really depends on each person. Some gain weight, others lose it. But I think it's not good for your intestines or something. (?)