Fueling Warmth: How Nutrition, Muscle and Biology Shape Your Resilience to Cold

Caroline Kavanagh | November 26, 2025

Strong muscles, smart fuel, and a bit of grit—she’s not just skiing through the cold, she’s thriving in it. Your body’s response to winter starts long before you hit the slopes.

As a sports nutritionist, I’ve seen again and again how the cold affects everyone a little differently—and most of my clients are surprised at just how much biology drives the process.

What keeps some people warm when others are reaching for their thickest hoodie? It comes down to several factors working together and understanding them can help you train, fuel and care for your body more effectively in all seasons.

Muscle mass is an important piece of the puzzle. Because muscle burns calories and produces heat during activity and even at rest, athletes and active folks with more muscle may notice they handle chilly weather with a bit more grace. That doesn’t mean you have to look like a bodybuilder—just that staying strong helps your body make and hold onto warmth.

But body size and shape matter, too. Smaller people tend to lose heat more quickly, simply because they have more skin surface compared to their overall volume. Bigger bodies, whether from build or mass, lose heat more slowly. Neither is “better,” but knowing your own tendencies can help you prepare—whether that’s packing an extra layer for a winter run or adjusting your warmup routine before training.

Another variable is how used you are to cold temperatures. The more you’re exposed to the cold—outdoor training, winter swims, brisk morning walks—the more your body learns to respond efficiently. Some adaptation is possible and it’s not just about willpower; it’s a real metabolic shift that comes with consistent exposure.

Let’s not forget genetics. Some populations, like the Inuit in Greenland, have adapted over many generations to thrive in freezing environments. Their bodies produce more brown fat, which acts like an internal heater by burning energy to make warmth. Even on an individual level, variants in certain genes can affect everything from how well you hold your core temperature to how your blood vessels respond when it’s cold out.

But where does nutrition fit in? This is where you have real influence, regardless of your genes or body type. Nutrition fuels your body’s ability to generate heat: carbohydrates and fats provide energy that both your muscles and your brown fat burn to keep you warm. Enough protein supports the development and maintenance of muscle, which not only powers your movement but gives your body extra capacity for heat production. Micronutrients—including B vitamins and iron—are critical for your metabolism to run efficiently, so you can turn food into usable fuel and warmth. And staying well-nourished helps regulate everything from blood flow to immune function, making you more resilient as conditions get colder.

So, what are the takeaways for athletes and active people? Pay attention to your own patterns—do you get cold faster than your teammates or training partners? Can you use nutrition and thoughtful training to boost your resilience? Building and maintaining muscle will help, but it’s part of a bigger picture that includes body size, regular exposure and your own unique genetics.

SUMMARY There’s no “one size fits all” when it comes to cold tolerance. But nutrition sits at the foundation—fueling heat production, supporting muscle and optimizing your body’s response to cold. The more you understand these factors, the smarter—and warmer—you can be all season long.