Strengthen Your Immune System: How to Stay Resilient as the Seasons Change

As the air gets colder and the days get shorter, it’s common to feel a dip in energy and for colds and bugs to start making their way into your home. Spending more time indoors, leaning into comfort foods, and losing daylight hours can all impact your body’s defenses.

The good news is that your immune system is not a mystery that randomly works or doesn't. It’s a living system that you can support every single day through the way you fuel, rest, and take care of your body.

If you’re showing up at the gym, you’re already doing something right for your immune health. Let’s talk about why and what else you can do to stay strong through the coming months.

Your Body’s Built-In Defense System

Your immune system has a layered defense strategy:

• First line of defense: your skin and mucous membranes. They’re like the castle walls, blocking viruses, bacteria, yeasts, and other foreign organisms from penetrating deeper tissues.

• Second line of defense: your lymphatic network. The lymphatic system transports immune cells, drains waste, and presents potential threats for elimination. Lymphatic endothelial cells actively regulate immune responses (Frontiers). The catch: the lymphatic system doesn’t have a pump like the heart. It depends on muscle contraction, movement, breathing, and internal pressure changes to circulate fluid.

• The gut–immune connection: Approximately 70–80% of the body's immune cells are located in the gut-associated lymphoid tissue (GALT), highlighting the critical role of the gut in immune function (NCBI).

Think of your immune system as an ecosystem that depends on your movement, internal environment, and nutrient support.

What Weakens the Immune System

When your defenses are already under stress, even small exposures can push you toward illness. Some of the strongest immune suppressors include:

• Sleep deprivation & chronic stress: Both profoundly affect innate and adaptive immunity (PMC)

• High sugar, alcohol, processed foods: these drive inflammation, oxidative stress, and compete with nutrient pathways (PMC, SD)

• Low protein intake: limits your body’s ability to produce antibodies, immune signaling molecules, and repair tissue (NCBI)

• Micronutrient deficiencies: particularly vitamins A, C, E, zinc, selenium, B vitamins, and essential fatty acids, all of which are key co-factors or antioxidants in immune pathways (MF)

• Other suppressors: medications (steroids, certain antibiotics), surgery, chemotherapy, environmental toxins, allergies, aging, and ongoing infections all create extra load on immunity (NCBI)

In fall and winter, these pressures increase with less sunlight, more indoor exposures, and less nutritious food cravings. It becomes easier to let your immune system fall below its optimal baseline.

Supporting Immunity Through Nutrition

Your diet is foundational. Here’s how to make your plate work for your immune system:

• Protein: Your body needs amino acids to build antibodies, immune-activating enzymes, and structural proteins (e.g. in gut lining). Prioritize quality protein around your workouts and across meals (NCBI).

• Antioxidants & co-factors: Vitamins A, C, E, zinc, selenium, and the B-complex vitamins help neutralize oxidative stress and support immune signaling. Eating a diverse “rainbow” of fruits and vegetables helps you cover more bases (NCBI).

• Healthy fats (Omega-3s, etc.): Fats support cell membranes (including immune cell membranes) and help regulate inflammatory processes. Fatty fish, flax, chia, walnuts, and other sources are your allies (PMC).

• Gut support: Fermented foods (e.g. kimchi, yogurt, kefir, sauerkraut) and high-fiber foods (vegetables, legumes, whole grains) feed beneficial microbiota, which in turn train and regulate your immune system (Stanford Medicine, PMC).

• Hydration: Well-hydrated mucous membranes are more effective barriers. Hydration also aids detoxification and waste removal (ResearchGate).

In short: prioritize real food, variety, and nutrient density. The more “whole food coverage” you provide, the better your immune system is equipped to respond.

Sleep, Stress, and Recovery

Your workouts are a form of stress (a healthy one), but recovery is where your immune system rebuilds and adapts. If sleep and rest are neglected, immunity takes the hit.

• Sleep: supports regeneration of immune cells, regulation of inflammatory processes, and adaptive immunity. Sleep deprivation has been shown to alter leukocyte populations, decrease antibody responses, and push the body toward chronic inflammation (PMC). One recent study showed that even one night of 24-hour sleep deprivation altered monocyte profiles in healthy individuals toward patterns seen in obesity/inflammation (The Journal of Immunology). This is a strong indication of how sensitive the immune system is to disruptions in sleep.

• Chronic stress / cortisol load: Prolonged elevation of cortisol suppresses immune function, suppresses lymphocyte activity, and impairs inflammatory balance (MDPI).

• Underrated recovery practices: Habits like breathwork, scheduled rest, deload weeks, mobility work, and consistency in sleep schedule are just as crucial as your workouts (Frontiers).

Keep Doing What You’re Doing and Build From There

Here’s a win you’ve already earned: by training regularly, you’re helping keep your lymphatic system moving and promoting immune health. Exercise consistently enhances the flow of immune cells between tissues and circulation, which improves immunosurveillance and lowers inflammation over time (PMC).

That said, overtraining or neglecting recovery can backfire, but with smart programming and awareness, your fitness practice is one of your greatest contributors to a resilient immune system.

Your immune system is working behind the scenes 24/7. Support it. Don’t expect perfect performance. Aim for consistency, foundational habits, and gradual improvements.