In the summer, bright sunlight keeps our metabolism running high, partly because insulin is a solar hormone and is stimulated by sunshine. When the days grow shorter and the temperatures drop, our bodies become more insulin resistant, want to conserve energy and store fat. The cold weather makes us want to stay bundled up indoors where we tend to remain sedentary and burn fewer calories.
In the winter time, it’s feeling the cold that takes over the metabolic work of summer sunshine. Feeling slightly cold activates brown adipose tissue, which helps burn stored energy for heat generation. The benefits of cold exposure include improved sleep, mood, focus, and metabolic health. So turn down the temperature on your radiators, and don’t bundle up when you’re out, you’ll want to stay slightly cool to keep your metabolic rate high. Just don’t let yourself get so cold that you start shivering, as that causes your muscles to seize up and burn glycogen for heat instead of fat.
Don’t use that extra duvet or blanket at night! The natural drop in core body temperature that happens during sleep is beneficial. Melatonin, the hormone associated with sleep, acts to lower the core body temperature, and a decrease in core body temperature is associated with both going to sleep and staying asleep. Feeling too warm at night leads to reduced sleep which impairs glucose tolerance and promotes insulin resistance, leading to an increased appetite, reduced energy use, and weight gain over time.
In addition to cooler temperatures, make sure you continue to get regular sunlight exposure, physical activity, and good sleep. Go for a walk first thing in the morning to set your circadian clock. Get some bright light exposure as soon as possible after waking up. Exercise outdoors on sunny days. Take vitamin D3 supplements to maintain healthy levels since you produce less vitamin D from sunlight in the winter. Create a comfortable, cool sleeping environment and stick to a regular sleep schedule. With some seasonal tweaks to your lifestyle habits, you can stay healthy and energetic all winter long.