The flu can lead to temporary weight loss. This is a common, short-lived effect of the body’s response to the influenza virus. Several factors contribute to this.
How the Flu Affects Your Weight
The flu often reduces appetite. Symptoms like nausea, a sore throat, and fatigue make eating difficult, leading to a decrease in calorie intake. This lower food consumption creates an energy deficit, contributing to weight reduction.
The body also expends more energy fighting infection. A fever, a common flu symptom, raises body temperature, which speeds up metabolism and burns more calories. This increased metabolic rate, combined with reduced food intake, can widen the energy gap and result in weight loss.
Much of the weight lost during the flu is often “water weight” rather than actual fat or muscle. Fever, sweating, vomiting, or diarrhea can cause significant fluid loss and lead to dehydration. This temporary fluid reduction can make the number on the scale drop quickly, but it typically returns once proper hydration is re-established.
Recovering Your Weight and Health
Rehydrating the body is a primary step in recovery and regaining lost fluid weight. Consuming plenty of fluids, such as water, broths, and electrolyte solutions, helps replace what was lost through fever, sweating, or gastrointestinal symptoms. Staying hydrated also supports the immune system.
As appetite gradually returns, focusing on easily digestible, nutrient-rich foods can aid in healthy weight recovery. Options like soups, plain toast, and fruits provide necessary calories and nutrients without overwhelming the digestive system. Prioritizing rest allows the immune system to recover and helps the body conserve energy for healing.
It is beneficial to gradually ease back into regular routines and strenuous physical activities once symptoms improve. Starting with lighter activities and slowly increasing intensity helps the body adapt without undue stress. Weight fluctuations during illness and recovery are common and generally temporary, with weight often returning to normal as health is restored.
When to Seek Medical Advice
While temporary weight loss during the flu is common, certain signs warrant medical attention. If weight loss is excessive or continues long after flu symptoms have resolved, it could indicate an underlying issue. Persistent flu symptoms that worsen or do not improve after the typical 5-7 day duration may also signal a secondary infection, such as pneumonia or bronchitis, which may require antibiotics.
Signs of dehydration, including severe thirst, reduced urination, dizziness, or confusion, indicate a need for professional assessment and potentially intravenous fluids. Difficulty breathing, shortness of breath, or chest pain are serious symptoms that require immediate medical care. Individuals with pre-existing conditions like asthma, heart disease, diabetes, or weakened immune systems, as well as young children and older adults, should contact a healthcare provider early if they develop flu symptoms due to a higher risk of complications.