An increased heart rate after eating is a normal physiological response. If your heart rate elevates radically after eating, however, it could be a sign of some other medical condition. Other factors unrelated to the meal but coinciding with meal times may also increase your heart rate. It is important, therefore, to catalogue all factors when determining the cause of your elevated heart rate after eating.
"Tachycardia" is the clinical term for an elevated heart rate. Though it typically indicates a medical emergency when tachycardia is mentioned in hospital-themed TV shows, the degree of the condition is what dictates its seriousness.
Mild tachycardia in a healthy person can be a routine physiological response. The term for tachycardia that occurs after eating is postprandial tachycardia.
Postprandial tachycardia occurs in most vertebrates. In humans, the increase has been measured through the intestinal blood flow, which is powered by the increased heart rate. Blood flow to the intestines after eating a meal generally maximises about 30 minutes after eating, when the blood flow to the intestines is approximately 130 percent of your body's fasting rate, note the authors of a 1991 study published in the journal "Gut."
Increased heart rate is generally caused by the neurotransmitters acetylcholine and norepinephrine. Your body releases these chemicals in response to physical or mental stress, such as exercise, fear or the anticipation of impending activity or stress. The normal tachycardia that occurs after eating is not triggered by either of these chemicals, but the exact triggering mechanism is not yet known with certainty, notes a study published in 2008 by the "American Journal of Physiology, Regulatory, Integrative and Comparative Physiology."
Duration and severity
The elevated heart rate's duration varies, so if you are attempting to calculate your resting heart rate for exercise, wait at least two hours after eating. If the reaction lasts longer than two hours or your heart feels as though it is pounding or throbbing, consult a doctor. This may be a sign of poor digestion, food allergies or heart or lung problems. In normal postprandial tachycardia, most people don't notice the elevated pulse.
Certain food and drink items may cause or intensify your post-meal heart rate increase. Caffeinated soft drinks, coffee or tea are common culprits, as are high-sugar or carbohydrate-laden foods. Some people have a noticeable response to salty foods or items containing monosodium glutamate. People with poor digestion, acid reflux and hernias are more likely to experience a racing heart after eating, reports Heart-Palpitations, a web resource for information on increased heart rates.
What to do
Keep a journal of your diet and heart rate to bring to your doctor. Measure your resting heart rate each morning before you get out of bed, and then take your pulse again before and after each meal. Note what you had for the meal and any other factors that might influence your heart rate, including exercise and stress. Discuss any other symptoms you have with your doctor, such as dizziness, breathlessness or heartburn.