Coffee is an undeniable part of the global culture and lifestyle. Its caffeine content, which helps people to focus, triggers energy and elevates mood, is appreciated almost everywhere.
However, for individuals who fast for medical checks, or to prepare for surgery, coffee might be a source of confusion. Can you drink coffee while fasting for tests? Doctors usually provide advice to individuals fasting for tests, but what is the opinion of healthcare professionals on the matter?
According to the American Society for Parenteral and Enteral Nutrition (ASPEN), caffeine is acceptable while fasting, but only in moderate amounts. This includes coffee, tea and other beverages with the same content.
Caffeine should not be confused with calorie-containing calories, such as soda and energy drinks. This because the added sugars, fats and proteins could interfere with the results of the tests.
Registered Dietitian Lakesha J. Lissalde, Ph.D., RD, LD, a Professor of Dietetics at East Carolina University, shared with U.S. News some tips for people fasting for medical exams. She recommends not taking more than 50-60 mg of caffeine a day and to spread the consumption throughout the day to avoid that the effect of caffeine keeps them up during the night.
Drinking coffee while fasting can cause dehydration, since coffee clears out both water and electrolytes from the body. Therefore, dehydration can be an issue, especially in the elderly, athletes and those with chronic illnesses. For this reason, some experts advise people to drink water in-between cups of coffee to hydrate properly.
On the other hand, since caffeine can regulate insulin resistance and glucose levels in the body, it can also interfere with test results indicating insulin resistance or diabetes. Because of this, it is important to follow the advice of your doctor for each individual case.
Does Caffeine Affect Blood Glucose Level?
When caffeine is consumed, it passes from the stomach to the small intestine and then the bloodstream, but it does not produce a dramatic change in the glycemic index or in the blood glucose level when consumed in moderate amounts.
According to the Centers for Disease Control and Prevention (CDC), it is probably safe for a person to have moderate amounts of caffeine in the morning, avoiding large doses at night, up to 24 hours before a blood glucose test.
However, further research is needed to assess the short-term effect of regular doses of caffeine on glucose levels.
Just like pre-diabetes, the effects of caffeine on the blood glucose level of those with type 2 diabetes are still inconclusive. While moderate doses of caffeine may help to reduce the risk of diabetes, high doses of caffeine could make it worse, so it should be avoided.
Can Caffeine Interfere With Other Tests?
According to David Grotto, Registered Dietitian and Nutritionist, caffeine can interfere with other types of tests, including anemia, pancreas and liver function tests.
Here, the opinion of experts differ, since some advise abstaining from caffeine before these tests and others recommend that one can drink it, up to 12 hours prior.
For this reason, it is always important to check with your doctor and follow their instructions.
In any case, individuals should avoid large doses of caffeine before the tests, as this can interfere with the results.
What Role Does the Duration of Fasting Play?
The duration of fasting for tests also plays an important role when it comes to one’s caffeine intake. Here, experts usually recommend abstaining from caffeine for 12 to 16-hour fasts.
On the other hand, for longer fasts, such as for 24 hours, it is probably safe to have up to 2 cups a day, the day prior to the test.
However, it is important to abstain from caffeine for at least 8 hours before the test, as it may interfere with the results and cause inaccurate results.
What Are the Alternatives to Drinking Coffee?
For those individuals who are fasting for tests, it is recommended to consume water and drinks like herbal teas and decaffeinated coffee instead.
These beverages hydrate and help with the detoxification process of the body, preparing individuals for their tests, while avoiding the side-effects of caffeine.
On the other hand, some experts advise against drinking herbal teas, since they can also act as diuretics and further increase the risk of dehydration.
In this case, it is important to always seek advice from a doctor.
Conclusion
Caffeine can be consumed while fasting for medical exams and tests, but in moderate amounts and depending on the duration of fasting.
It is important to be aware that caffeine can interfere with test results, dehydrate the body and increase blood glucose levels.
Before consuming coffee or tea, individuals should consult their doctor for further advice and recommendations.
