Do You Burn More Calories When Sick? The Science Behind Illness and Metabolism

Do You Burn More Calories When You're Sick?

It's a common belief that your body burns more calories when you're sick. After all, fighting off an illness causes changes in your body that require extra energy. But is this really true? Let's take a closer look at what happens to your metabolism when you have an infection.

Why Your Metabolism Changes When Sick

When your immune system detects an invading virus or bacterium, it kicks into high gear to kill off the foreign invaders. This ramps up inflammation and causes your body temperature to rise - resulting in fever. All of these immune responses require extra energy.

To provide that energy, your body starts burning more calories. This acts to "fuel the fire" of your elevated immune response. Some of the ways your metabolism shifts into high gear include:

• Your cells work harder to fight infection, burning glucose and fat stores for energy
• Hormones like epinephrine (adrenaline) are released, signaling your body to break down more fat and glycogen
• Inflammatory cytokines activate calories-burning pathways
• Your heart beats faster to shuttle immune cells, using more energy

How Many More Calories Does Your Body Burn?

Research shows that your body can burn up to 50% more calories when fighting certain illnesses. For example, studies have found that people with the flu have elevated resting metabolic rates around:

• 12% higher on the first day of infection
• 16% higher a few days into the illness
• Up to 39% higher at the peak infection stage

Other viral illnesses have been shown to boost daily calorie burn by:

• 13-15% for the common cold
• Up to 50% for mononucleosis infections like mono

Bacterial infections can also lead to extra calorie burning, though less research exists on these specifically.

The Impact on Appetite

If your body torches more calories while sick, does that mean you'll automatically lose more weight? Not necessarily.

That's because sickness often suppresses appetite. So even though your metabolism spikes, you may eat fewer calories overall.

Factors impacting appetite and eating habits when unwell include:

• Nausea, vomiting, diarrhea making eating unappealing
• Fatigue reducing motivation to obtain or prepare food
• Loss of taste and smell diminishing enjoyment of meals
• Sore throat or stuffy nose making eating uncomfortable
• Medications that list appetite loss as a side effect

With poor intake, you won't reap the potential "calorie-burning benefits" of being sick. You also risk becoming nutrient deficient, setting back your recovery.

Tips to Support Metabolism When Sick

To get the most out of your revved-up sick day metabolism - without compromising health - follow these tips:

1. Drink fluids to maintain energy levels without irritating your throat or stomach
2. Choose nutritious soups and smoothies that provide nourishment from vitamins, minerals, and antioxidants
3. Stick to bland foods like toast, rice, applesauce and eggs if struggling with indigestion or nausea
4. Get plenty of rest to allow your body to direct maximum energy towards infection-fighting pathways
5. Ask your doctor if fever-reducer medication may be helpful for bringing down an extremely high temp

The Bottom Line

Research confirms that common illnesses like flu, cold, strep, and mono can significantly elevate daily calorie burn. But increased metabolism often coincides with poor appetite and eating habits that negate any potential weight loss effects.

By supporting your body with proper rest and nutrition during sickness, you allow your super-charged metabolism to work in your favor. Focus on getting well first before viewing an illness as a strategy for losing weight or accelerating calorie burn.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.