How Your Weight Affects Your Immune System

You’re probably well aware that being overweight puts you at higher risk of heart disease, diabetes and some cancers.

But did you know that obesity also weakens your immune system, making you more likely to catch viruses and develop other infections?

How does your immune system work?

Your immune system’s job is to protect your body against infection. It’s a big task so various parts of your body are involved including your skin, bone marrow, white blood cells, spleen and mucous membranes. Your lymphatic system plays an important role transporting lymph around your body (that’s a fluid containing white blood cells that fight infection).

How does weight affect your immune system?

The different kinds of cells that form your immune system need to co-exist in the right balance to keep you in robust health. Your diet and weight can upset this balance and tip you into a state of low-grade chronic inflammation.

Excess body fat affects your immune system by:

  • Triggering production of pro-inflammatory immune cells that circulate through your bloodstream and can damage your body
  • Activating macrophages, another type of inflammatory immune cell that can cause insulin resistance
  • Infiltrating your spleen, bone marrow and thymus, reducing the production and storage of immune cells and replacing them with fat cells instead.

In short, obesity results in an immune system that makes fewer, and less effective, immune cells. You’re no longer sending a full fighting force of immune cells to tackle potential infections; instead you’re sending in a few feeble cells that are easily overcome by invading pathogens.

What kinds of infections are we talking about?

Obesity is an independent risk factor for many infections including:

  • Abscesses & wound infections
  • Bacterial and fungal skin infections
  • Respiratory tract infections
  • Urinary tract infections
  • Pneumonia
  • Clostridium difficile colitis
  • The 2009 A(H1N1) influenza pandemic.

What about COVID-19 risk?

Several studies now show that obese people are at greater risk of COVID-19 than people of a healthy weight.

One study found that obese patients with COVID-19 were:

  • 113% more likely to need hospitalisation
  • 74% more likely to be admitted to an intensive care unit
  • 48% more likely to die.

If you’re overweight or obese, your heightened COVID-19 risk is not only about your immune system. It’s also about your lung capacity, chronic inflammation and propensity to blood clots. But a weakened immune system means you’re less likely to fight off the virus.

How can you strengthen your immune system?

Because your immune system is an intricately connected network that extends throughout your body. Despite any number of products claiming to ‘boost your immune system’, there is no magical ‘quick fix’.

Your immune system responds well to a healthy lifestyle. In fact, every part of you does. So, the best advice for a healthy immune system is the same advice that you’ve heard many times before about living well.

That includes:

  • Not smoking
  • Eating plenty of fruits and vegetables
  • Exercising regularly
  • Limiting alcohol consumption (if you drink)
  • Getting enough sleep
  • Reducing stress
  • Maintaining good hygiene to avoid infection, e.g. washing your hands (you know the drill by now!)
  • Maintaining a healthy weight.

How can Life Weight Loss Centre help?

We can support you to lose weight through lifestyle change, bariatric surgery and ongoing support.

At your initial consultation, we’ll chat through your goals and medical needs. We’re here to help you achieve and maintain a healthy weight – and we know that takes more than a medical procedure. That’s why we provide extensive pre-and post-op support and care, including regular catch-ups, meal planning, exercise regimes and goal setting.

We’ve supported thousands of people just like you to achieve their goals through our comprehensive surgical and behavioral health program.

If you’d like to learn more, please make an appointment.


All information is general in nature. Patients should consider their own personal circumstances and seek a second opinion. Any surgical or invasive procedure carries risks.

Want to know more?

Request a callback from one of our friendly Practice Managers


Want to know more? Request a callback

Want to know more?

Request a callback from one of our friendly Practice Managers