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Obesity and Weight Management

Weight loss due to illness



Is there a physiological reason that a person would gain weight immediately following an episode of gastroenteritis (with diarrhea)? Wouldn`t I expect weight LOSS following such an illness?


If you`re asking for a specific diagnosis, which is more than I can provide online, then, only a detailed history and physical exam by a healthcare professional can provide enough information to make a specific diagnosis. Please discuss your further concerns with your healthcare provider.

Please find below a possible physiological explanation. Our bodies contain fluid made up of these major electrolytes sodium (Na+), calcium (Ca++), potassium (K+), chloride(Cl-), and bicarbonate (HC03-). They are in solution in the body with water (H2O) as the solvent. Slight changes in water balance or serum electrolyte concentrations causes major changes in body function. Water and electrolyte imbalances are common in many diseases. Gastroenteritis is the inflammation of the stomach, small, and large intestine. Viral gastroenteritis is an infection caused by viruses resulting in diarrhea or vomiting. Body water loss (dehydration) is when output exceeds input. This may be decreased intake, increased output or both(gastroenteritis).

Total body water changes can be accompanied by proportional changes in sodium (Na+). When there is a proportional gain of total body water and sodium, so that the total body water is increased, but serum sodium remains within normal limits ( as for example: excessive fluid input), then, weight gain, increased BP, edema, and increased urine output may be symptoms that occur. The recommended treatment for gastroenteritis usually begins with fluids taken orally to prevent dehydration. If your body took in too many fluids this could be a reason for weight gain.

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Response by:

Dennis   Mungall, PharmD Dennis Mungall, PharmD
Associate Professor, Pharmacy Practice
College of Pharmacy
The Ohio State University

Maria Papouras-Volakis, PharmD Student, BS Pharmacy
Staff Pharmacist
Nationwide Children's Hospital
The Ohio State University