When you become ill, your body triggers a "sickness metabolism," which involves a burning of additional calories to support your immune system in combating the disease. This metabolic adaptation means your body is working harder than usual to stave off the infection, often exposing itself through symptoms like muscle aches, lowered appetite levels, and fever.

Being sick redirects your energy towards your body's immune response, reducing the focus on other operations. Precisely because of this, when you're unwell, it becomes more critical to consume a nutritious diet and stay hydrated - your immune defense needs the extra fuel to function effectively.

This energy diversion explains why some may experience weight loss during illness periods. When healthy, diet+ workout efforts lead your body to burn roughly 70%-80% of its required calories from fat reservoirs, retaining a minor portion from protein dissolution. But this changes when you fall sick. Your body draws around 30% more calories than usual from protein or muscle deposits. Hence, a balanced diet is essential not only to prevent weight loss but also to conserve muscle mass, considering the role protein plays in health management.

The exact number of calories burned during sickness can vary based on how severe the illness is. For instance, a fever will typically result in the burning of more calories because it is your immune system’s way of combatting the virus. The raised body temperature boosts the metabolic rate, causing a calorie burning increase.

Attention to nutrition is crucial, but don't forget a major part of illness recovery is self-care. Contrary to outdated advice about "feeding a cold and starving a fever," retaining hydration, nutrition, and rest should always be your top priority. Remember, your body works overtime to fight off the offending pathogens when you're down with a cold or the flu, burning extra calories in the process.

Knowing how to manage your diet and fluid intake during sick periods can replenish burnt calories and nurture your immune system, and hopefully, get you back on your feet faster. However, if you notice your health not improving or worsening, it's a sign your immune system might be overwhelmed, warranting a doctor's attention.

This article was authored by Anna Giorgi, an experienced freelance health and wellness writer having more than a quarter-century of experience in wellness-oriented content writing.