Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Digestion Time
Name:  jennifer
Status:  student
Age:  19
Location: N/A
Country: N/A
Date: 2000-2001

Approx. how long does it take for you to digest food?? Nutritionist say that ou should wait 20 mins until you have a second helping of food, is this true?? thank you very much

This is a very general question. It depends on the food...some are quickly simple carbohydrates (cooked rice) and some are much slower like complex carbs (beans). It also depends on what part of the food that you are asking about. Foods contain starch, fat, oils, protein, nucleotides etc. which each have different mechanisms and rates of digestion. If you eat a Snickers bar you will digest the sugar quite quickly...matter of minutes whereas the nuts take hours. As far as how often you should eat is even more controversial. I believe we as hunter gatherers evolved to eat small meals of nuts, fruits, and vegetables often and, on rare occasions gorge on a big meal of meat or fish. I of course being Italian think that the main reason for living is to eat (edeo ergo sum...I eat therefore I am) I might not be the best person to ask.


It takes several days for food to make its way all the way through your system.

It's not that the first helping is digested in 20 minutes, it's that it takes about 20 minutes for your hunger to turn off after you eat. So the 20 minute rule is to keep you from overeating.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

Click here to return to the Zoology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory