Hello! The black out that you experience when you get up fast comes from orthostatic hypotension. Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even faint. Orthostatic hypotension is often mild, lasting a few seconds to a few minutes after standing. However, long-lasting orthostatic hypotension can be a sign of more-serious problems, so talk to your doctor if you frequently feel lightheaded when standing up. It s even more urgent to see a doctor if you lose consciousness, even momentarily. Mild orthostatic hypotension often doesn t need treatment. Many people occasionally feel dizzy or lightheaded after standing, and it s usually not cause for concern. The treatment for more-severe cases of orthostatic hypotension depends on the cause. When you stand up, gravity causes blood to pool in your legs. This decreases blood pressure because there s less blood circulating back to your heart to pump. Normally, special cells (baroreceptors) near your heart and neck arteries sense this lower blood pressure and send signals to centers in your brain that in turn signal your heart to beat faster and pump more blood, which stabilizes blood pressure. In addition, these cells cause blood vessels to narrow, which increases resistance to blood flow and increases blood pressure. After eating meals. Some people experience low blood pressure after eating meals (postprandial hypotension). This condition is more common in older adults.You need to eat regularly in moderate amounts. Include more protein in your eating susch as fish, chicken, egg, white egg, cheese, cottage cheese, milk, yogurt, more fruits and vegetables and less carnbohydrates such as pasta, white bread and rice, cookies. Best regards. Exercise. Do weight training because it build up muscle and the more muscle you have the more calorie you will burn.