Hi welcome to HCm Sometimes you feel dizzy or lightheaded after eating a meal this is due to the reason , blood pressure goes low after eating . And also nubmness in hand in swimming pool is caused by low BP Digestion is a complicated job that requires precise coordination between the digestive, nervous, and circulatory systems . In some people, the heart and blood vessels don’t respond as they should. That causes blood pressure to decrease everywhere but the digestive system. The sudden drop usually announces itself as dizziness or lightheadedness is called postprandial hypotension. Some people are genetically predisposed to postprandial hypotension. In others, it comes on after a stroke, accident, or other trauma damages key nerves or blood pressure sensors . You can avoid several lifestyle changes which can make a difference: . Drinking 12 to 18 ounces of water 15 minutes before eating can evade a fall in blood pressure. Larger meals are more likely to trigger postprandial hypotension than smaller ones. . White bread and other foods made with highly refined flour, white rice, potatoes, and sugary beverages pass quickly from the stomach to the small intestine. This rapid transit contributes to postprandial hypotension. Slowly digested whole grains, beans, protein, and healthy oils may keep your blood pressure up after a meal. It is advised to see your doctor for further guidance . Hope this helps solves your query .Take care , All the best .Wish Get well soon . Don t hesitate to get back tf have any further query .