OLD Why Brrrn Burn more calories The body burns more calories in cooler temperatures than in ambient or hot temperatures. Burn fat When exposed to cooler temperatures, 64°F or lower, the body may turn to burning fat as fuel to stay warm. Feel Less Cold Frequent exposure to cooler temperatures can increase your tolerance to cold in response to the changing environment. Optimal Temperature The body may take longer to fatigue in cooler temperatures. Therefore, heat may limit our bodies ability to perform at its best.