The common observation that women frequently report feeling colder than men is supported by distinct physiological differences in how the body generates, distributes, and regulates heat. Understanding this phenomenon requires looking at the biological machinery responsible for maintaining a stable internal temperature. The discrepancy in thermal comfort between the sexes is rooted in fundamental variations in metabolism, circulatory responses, and hormonal fluctuations that modulate the body’s internal thermostat.
Differences in Basal Metabolic Rate
The primary engine for internal heat production is the body’s metabolism, specifically the Basal Metabolic Rate (BMR). BMR represents the minimum amount of energy required to sustain life’s basic functions while at rest, and this energy expenditure creates heat as a byproduct. On average, women possess a lower absolute BMR than men, meaning their bodies produce less heat at rest.
A major factor driving this difference is body composition, particularly the proportion of metabolically active tissue. Muscle tissue is significantly more energy-demanding and heat-generating than fat tissue. Since men typically have a higher ratio of muscle mass to fat mass, their resting heat production is inherently greater.
For comparison, the average BMR for men is approximately 1,696 calories per day, whereas the average BMR for women is around 1,410 calories per day. This lower energy expenditure directly translates to a reduced capacity for internal thermogenesis. The result is that women often start with a lower baseline of heat generation, making them more susceptible to feeling cold when environmental temperatures drop.
Peripheral Blood Flow and Core Heat Conservation
While heat production is the first step, the sensation of being cold often stems from how that heat is distributed and conserved throughout the body. The body’s thermoregulatory system prioritizes maintaining the core temperature of internal organs to ensure survival. This defense mechanism involves a process called vasoconstriction, where blood vessels near the skin’s surface narrow.
This narrowing reduces blood flow to the body’s shell, or extremities, which decreases the amount of heat lost to the surrounding environment. The process effectively increases the skin’s insulative properties, keeping the heat constrained within the torso and vital organs. The consequence of this conservation strategy is a significant drop in the temperature of the skin, especially in the hands and feet.
Women often initiate this conservation response sooner and more aggressively than men. Because the extremities are receiving less warm blood, the skin temperature in the fingers and toes can be several degrees colder than in men, leading to the uncomfortable feeling of coldness. This physiological trade-off between a warm core and cold extremities is a protective measure that directly explains the common complaint of cold hands.
The body fat women typically carry, which is often a higher percentage than in men, acts as a layer of insulation that helps protect the core temperature. This insulation supports the effectiveness of vasoconstriction by trapping the metabolic heat closer to the core. Therefore, while the core temperature may be well-defended, the reduced blood flow to the surface is what triggers the sensation of coldness in the periphery.
The Role of Hormones in Thermal Sensitivity
The body’s perception of temperature is actively modulated by fluctuating reproductive hormones. The female menstrual cycle introduces cyclical changes in thermal sensitivity by altering the hypothalamic set point, which acts as the body’s internal thermostat.
After ovulation, during the luteal phase, progesterone rises significantly. Progesterone has a thermogenic effect, causing an upward shift in the core body temperature set point, typically 0.3°C to 0.7°C higher than the follicular phase.
When the thermostat is set higher, a standard room temperature that was previously comfortable feels colder in comparison. The body perceives a need to generate more heat to meet this elevated set point, which can increase sensitivity to cold during this phase of the cycle. Progesterone appears to achieve this by inhibiting heat-loss mechanisms.
Conversely, estrogen, which is dominant in the follicular phase, tends to lower the regulated body temperature. Estrogen promotes heat loss by encouraging vasodilation, which allows more heat to escape through the skin. This hormonal interplay ensures thermal regulation is a dynamic process, contributing to the fluctuating experience of coldness throughout the month.