Why You Might Experience Weight Loss When Sick

Table of ContentsView AllTable of ContentsCausesDurationComplicationsWhen to See a ProviderPrevention

Table of ContentsView All

View All

Table of Contents

Causes

Duration

Complications

When to See a Provider

Prevention

You may lose weight when you’re sick, especially if you have a stomach bug or another illness that causes nausea or affects your appetite. Illnesses that cause vomiting will cause you to lose body fluid, which can cause you to lose 1 or 2 pounds. This type of weight loss, however, isn’t usually permanent.

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Causes of Weight Loss

If you have diarrhea and vomiting multiple times, you lose a lot of body fluid in a short amount of time. You may also find it hard to keep food or liquids down, so you may not be able to replace what you have lost.

This drastic change in fluid volume in your body can show up on the scale. If your symptoms last for several days, the weight change can be significant.

Can you lose weight while sick with COVID-19 or a cold?Viral illnesses such as COVID-19 or the common cold can cause loss of appetite, which may lead to temporary weight loss. These illnesses may also cause nausea and vomiting, which may result in the same type of weight loss you would experience during a gastrointestinal illness.

Can you lose weight while sick with COVID-19 or a cold?

Viral illnesses such as COVID-19 or the common cold can cause loss of appetite, which may lead to temporary weight loss. These illnesses may also cause nausea and vomiting, which may result in the same type of weight loss you would experience during a gastrointestinal illness.

Duration of Weight Loss

Since most of the weight that comes off when you are sick is “water weight,” it will likely come back when you are feeling better and eating and drinking again. This is because when you are vomiting, you aren’t losing fat. Your body is trying to get rid of the virus, bacteria, or other germs that are making you sick.

Vomiting anddiarrheaare the symptoms of the illness—your body’s defense against the germs. It eliminates any food and liquid in your digestive tract in an attempt to kill those germs.

Once you have recovered and can return to eating as you did before, all (or at least most) of the weight will return because you will be able to hold food and liquids down again.

What illness causes rapid weight loss?Other more serious illnesses can cause rapid, unexplained weight loss, such as chronic digestive disorders and certain kinds of cancer.If you are experiencing rapid weight loss and you don’t know why, it’s important to contact your healthcare provider so you can receive the right diagnosis and treatment.

What illness causes rapid weight loss?

Other more serious illnesses can cause rapid, unexplained weight loss, such as chronic digestive disorders and certain kinds of cancer.If you are experiencing rapid weight loss and you don’t know why, it’s important to contact your healthcare provider so you can receive the right diagnosis and treatment.

The biggest risk and concern with the stomach flu for most people is dehydration. This is more likely to occur in young infants and children as well as older adults.

Signs ofdehydrationin older children and adults include:

Signs of dehydration in infants and young children include:

When to Seek Medical Attention

If you are concerned about dehydration, contact your healthcare provider or seek medical attention. In some cases, dehydration can be managed at home if you or your child are able to keep down fluids.

It’s important to resume eating and drinking slowly if you have been vomiting; adding too much too quickly can cause vomiting to return or worsen. If you are unable to hold any amount of fluids down, contact your healthcare provider.

There are medications you may be able to take to stop vomiting. If dehydration is severe enough, you may need IV fluids to recover.

If you are ever with someone who appears to be dehydrated and loses consciousness, seek medical help immediately. Do not try to give an unconscious person anything to drink.

If you have symptoms of a stomach bug that last longer than a week (or persistent vomiting for more than 24 hours), contact your healthcare provider. Most cases of gastroenteritis go away on their own after a day or two. Diarrhea can last longer but should improve over time.In some cases, there could be another cause of your symptoms and you may need additional tests or treatments.

The best thing you can do is to avoid getting sick in the first place. It isn’t always easy, especially if someone else in your house has a virus, but there are steps you can take to try to limit the spread of those germs.

Washing your hands is essential. Wash them as frequently as you can:Before and after you prepare foodBefore and after you eatAfter you use the bathroomAfter you change a diaperAfter you touch anything that a sick friend or family member has touched

Washing your hands is essential. Wash them as frequently as you can:

Summary

If you have signs of dehydration after a gastrointestinal illness, it’s important to seek medical attention. You may require additional treatment to stop vomiting and fluids to manage dehydration.

6 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Balsalobre-Arenas L, Alarcón-Cavero T.Rapid diagnosis of gastrointestinal tract infections due to parasites, viruses, and bacteria.Enferm Infecc Microbiol Clin.2017;35(6):367–76. doi:10.1016/j.eimce.2017.01.033Bosch X, Monclús E, Escoda O, et al.Unintentional weight loss: Clinical characteristics and outcomes in a prospective cohort of 2677 patients.PLoS One. 2017;12(4):e0175125. doi:10.1371/journal.pone.0175125Shah MP, Hall AJ.Norovirus illnesses in children and adolescents.Infect Dis Clin North Am. 2018;32(1):103–118. doi:10.1016/j.idc.2017.11.004American Academy of Pediatrics.Signs of dehydration in infants & children.Gawronska J, Koyanagi A, López Sánchez GF, et al.The prevalence and indications of intravenous rehydration therapy in hospital settings: A systematic review.Epidemiologia (Basel). 2022;4(1):18-32. doi:10.3390/epidemiologia4010002Zollner-Schwetz I, Krause R.Therapy of acute gastroenteritis: role of antibiotics.Clin Microbiol Infect. 2015;21(8):744-9. doi:10.1016/j.cmi.2015.03.002Additional ReadingAmerican Academy of Pediatrics.Signs of dehydration in infants & childrenMedlinePlus.DehydrationMedlinePlus.Weight loss - unintentional

6 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Balsalobre-Arenas L, Alarcón-Cavero T.Rapid diagnosis of gastrointestinal tract infections due to parasites, viruses, and bacteria.Enferm Infecc Microbiol Clin.2017;35(6):367–76. doi:10.1016/j.eimce.2017.01.033Bosch X, Monclús E, Escoda O, et al.Unintentional weight loss: Clinical characteristics and outcomes in a prospective cohort of 2677 patients.PLoS One. 2017;12(4):e0175125. doi:10.1371/journal.pone.0175125Shah MP, Hall AJ.Norovirus illnesses in children and adolescents.Infect Dis Clin North Am. 2018;32(1):103–118. doi:10.1016/j.idc.2017.11.004American Academy of Pediatrics.Signs of dehydration in infants & children.Gawronska J, Koyanagi A, López Sánchez GF, et al.The prevalence and indications of intravenous rehydration therapy in hospital settings: A systematic review.Epidemiologia (Basel). 2022;4(1):18-32. doi:10.3390/epidemiologia4010002Zollner-Schwetz I, Krause R.Therapy of acute gastroenteritis: role of antibiotics.Clin Microbiol Infect. 2015;21(8):744-9. doi:10.1016/j.cmi.2015.03.002Additional ReadingAmerican Academy of Pediatrics.Signs of dehydration in infants & childrenMedlinePlus.DehydrationMedlinePlus.Weight loss - unintentional

Balsalobre-Arenas L, Alarcón-Cavero T.Rapid diagnosis of gastrointestinal tract infections due to parasites, viruses, and bacteria.Enferm Infecc Microbiol Clin.2017;35(6):367–76. doi:10.1016/j.eimce.2017.01.033Bosch X, Monclús E, Escoda O, et al.Unintentional weight loss: Clinical characteristics and outcomes in a prospective cohort of 2677 patients.PLoS One. 2017;12(4):e0175125. doi:10.1371/journal.pone.0175125Shah MP, Hall AJ.Norovirus illnesses in children and adolescents.Infect Dis Clin North Am. 2018;32(1):103–118. doi:10.1016/j.idc.2017.11.004American Academy of Pediatrics.Signs of dehydration in infants & children.Gawronska J, Koyanagi A, López Sánchez GF, et al.The prevalence and indications of intravenous rehydration therapy in hospital settings: A systematic review.Epidemiologia (Basel). 2022;4(1):18-32. doi:10.3390/epidemiologia4010002Zollner-Schwetz I, Krause R.Therapy of acute gastroenteritis: role of antibiotics.Clin Microbiol Infect. 2015;21(8):744-9. doi:10.1016/j.cmi.2015.03.002

Bosch X, Monclús E, Escoda O, et al.Unintentional weight loss: Clinical characteristics and outcomes in a prospective cohort of 2677 patients.PLoS One. 2017;12(4):e0175125. doi:10.1371/journal.pone.0175125

Shah MP, Hall AJ.Norovirus illnesses in children and adolescents.Infect Dis Clin North Am. 2018;32(1):103–118. doi:10.1016/j.idc.2017.11.004

American Academy of Pediatrics.Signs of dehydration in infants & children.

Gawronska J, Koyanagi A, López Sánchez GF, et al.The prevalence and indications of intravenous rehydration therapy in hospital settings: A systematic review.Epidemiologia (Basel). 2022;4(1):18-32. doi:10.3390/epidemiologia4010002

Zollner-Schwetz I, Krause R.Therapy of acute gastroenteritis: role of antibiotics.Clin Microbiol Infect. 2015;21(8):744-9. doi:10.1016/j.cmi.2015.03.002

American Academy of Pediatrics.Signs of dehydration in infants & childrenMedlinePlus.DehydrationMedlinePlus.Weight loss - unintentional

American Academy of Pediatrics.Signs of dehydration in infants & children

MedlinePlus.Dehydration

MedlinePlus.Weight loss - unintentional

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Causes of Weight Loss#

Can you lose weight while sick with COVID-19 or a cold?#

Duration of Weight Loss#

What illness causes rapid weight loss?#

When to Seek Medical Attention#

Summary#