Why do I lose weight when I get the flu?

Why do I lose weight when I get the flu?

I just lost 5 pounds in the last three days. I’ve been sick with the flu. Time to celebrate! Is this a silver lining whenever I get sick? Well, unfortunately it’s not. Chances are, the weight is slowly coming back. In this article, we will answer the question – why do I lose weight when I get the flu?

Water Loss
First off, most of the weight we have lost has been water weight. With all of those trips to the bathroom with vomiting and diarrhea, we’ve been losing more water than what we’ve been taking in. It wasn’t 5 pounds of fat that I lost when I got the flu, it was the water from my diarrhea. 

Loss of Appetite
What about my appetite? I wasn’t eating much, if anything, when I was sick. I think it’s strange that we lose our appetites whenever we get sick. You see, our lowered drive to eat may actually free up some energy to mount our immune response, says Dr. Donald D. Hensrud, chair of the Division of Preventive, Occupational and Aerospace Medicine at the Mayo Clinic. “Digesting food also takes energy, so if we’re not digesting food, it frees up energy to help fight an infection or illness.” The weight will usually return whenever our normal eating habits return.

Perhaps the best part of losing weight, even if it is from the flu, is the inspiration we feel when ever we do lose weight. Perhaps now is the time to think about eating a more healthy diet. Maybe it’s time for more vegetables on our dinner plates?

How much have you lost after getting the flu? Let us know in your comments below.


Gary is one of the founders of RetireBook, and is the site engineer and also one of its writers. He has been working in IT for over 25 years, is a world traveler, and enjoys everything about living in the Pacific Northwest. He is full of energy, loves the outdoors, climbed several mountains, volunteers in his community, and has been saving his whole life for an early retirement that will be coming up in just a few short years.