The Wonders of Brown Fat and the Seasons Welcome to our daily Bitachon as we continue in our Shaar Habechina series. We are discussing the seasons right now, and today we explore a very interesting advantage of the changing weather: how seasons affect our brown fat. What is Brown Fat? Most of the fat in our body is referred to as white fat. That is what stores extra energy and calories—the stuff we usually don't like. While it is good to have reserves for the future, most of us aren't living in times of starvation, so we just keep those reserves for long periods. Brown fat, however, has a different job: it burns that extra energy from the white fat as fuel to produce heat. The Furnace vs. The Warehouse Think of it this way: White Fat: Your storage warehouse (usually found in the stomach or thighs). Brown Fat: Your furnace. It pulls fatty acids out of storage and into your bloodstream to burn them. Brown fat is highly sensitive to the change in seasons—specifically the drop in temperature and the change in daylight. When the weather turns cold, your body receives signals to recruit more brown fat. In fact, brown fat activity can be four times higher in January than in July. Individuals with active brown fat burn about 15% more calories compared to those with very little of it. The Problem with "Thermal Monotony" The problem is that modern humans live in a state of thermal monotony . We keep our houses at a steady 70°F year-round, which makes our brown fat lazy. To counter this, it is good to embrace the cold: Spend a few hours a day in the 62°F to 66°F range. Sleep in a cool room at night. End your shower with a 60-second cold blast. The shock of cold water on your upper back and neck—where most brown fat is stored—tells the brain to ignite the furnace. The Big Chiddush: Cold vs. Heat Here is the big chiddush (innovation): Exercise already helps convert white fat, but if you go for a run or a walk, try doing it when it's cold outside. If you exercise in a hot gym, your body focuses on cooling you down through sweating. But if you exercise in the cool air, your body gets a double hit: it burns energy from the workout and burns energy to maintain your core temperature. Despite the old wives' tales, wearing a sweatsuit to lose weight is a mistake. Sweating itself doesn't make you lose weight, burning calories for energy or heat does. Next time you go out, wait a few minutes before putting on your heavy jacket. Let yourself feel that brisk air to tell your body to recruit more brown fat. A Wonder of Creation Newborn babies are born with a lot of brown fat (5% of their body weight) because they aren't strong enough to shiver to stay warm. As we get older, we lose much of it because we gain the ability to shiver, but seasonal cold exposure helps keep what we have active. The Benefits of Brown Fat: Metabolic Boost: It burns blood sugar and fat molecules to create heat. Insulin Health: It "eats" sugar to fuel heat production, stabilizing blood sugar levels. Heart Health: It can help lower blood pressure. It is truly a "wonder of wonders" what God has going on inside of us. And the hero behind it all? That "one-two punch" of the sun and the axis tilt of the Earth.