You might not think twice about feeling sluggish following a large meal, but if you feel dizzy or unstable on your feet, low blood pressure might be the cause. Measuring your blood pressure before and after a meal helps you identify low blood pressure issues after eating, a condition also known as postprandial hypotension. Although resting blood pressure varies among individuals, health care professionals typically label readings lower than 90 millimeters of mercury or mm Hg systolic -- top number -- or 60 mm Hg diastolic on the bottom as "low."
Supply and Demand
Your cardiovascular system works to regulate and deliver blood to your entire body. When you exercise or physically exert yourself, your muscles use up existing energy and need both oxygen and carbohydrates to continue functioning. Sensing the demand, a properly functioning cardiovascular system increases your blood flow to your muscles. Similarly, after a large meal, your body redirects blood flow to your intestines to aid with digestion.
Checks and Balances
Blood volume and blood pressure both rise and fall during the day, depending on a myriad of circumstances. Anxiety, increased sodium intake and exposure to cold all can raise your blood pressure. Rest, limiting salt intake and medications, in turn, can lower blood pressure. Ordinarily, when you eat a large meal, your body adapts to the increased blood flow to the intestines and resulting drop in circulating blood volume and pressure by constricting blood vessels, which helps increase blood pressure back to normal levels.
Aging
As you age, your blood vessels lose some of their elasticity. Chronic high blood pressure and smoking contribute to further stiffening. Although your cardiovascular system receives signals sent to blood vessels to constrict, thereby raising lowered blood pressure pursuant to a meal, stiffened vessels cannot adequately comply. A weakened or damaged heart muscle might not have the strength to pump harder to increase blood volume and blood pressure. As many as one-third of all older adults experience symptoms associated with postprandial hypotension, according the Merck Manuals, including dizziness and falls.
Prevention
Eating smaller meals that are lower in carbohydrates can help you avoid symptoms associated with a drop in blood pressure. Drinking a caffeinated beverage before or with a meal can also help keep blood pressure levels up. Lie down after a meal if you are able and rest while you digest your meal. Avoid taking blood pressure medications just before eating. Always discuss symptoms with your doctor to confirm that your symptoms relate to postprandial hypotension and eliminate other possible causes, including diabetes, neurological disorders or problems with medications.
