Extreme cold can slow your metabolism. Why does your body burn more calories in winter?

The relationship between cold weather and our body's metabolism can seem confusing. We hear that metabolism might slow in extreme cold, yet also that we burn more calories during winter. Both ideas hold some truth, depending on the circumstances, but the primary effect for most people experiencing typical cold weather is an increase in energy expenditure. Let's explore how our bodies respond to chilly temperatures.

Metabolism and Maintaining Body Heat

Our metabolism encompasses all the chemical processes that keep us alive, and these processes require energy, measured in calories. Our basal metabolic rate (BMR) is the energy we burn simply staying alive at rest. The body works constantly to maintain a stable core temperature, around 37°C (98.6°F). When exposed to cold, this task becomes more demanding, requiring the body to generate extra heat – a process called thermogenesis. This increased heat generation is why we often burn more calories in the cold.

How the Body Generates Heat (and Burns Calories)

The body has two main ways to produce extra heat in response to cold, both of which increase calorie consumption:

• Shivering: This is the body's rapid, involuntary response to feeling cold. Muscles contract and relax quickly, generating heat through friction and metabolic activity. Shivering is effective but energetically expensive and can be uncomfortable.
• Non-Shivering Thermogenesis (NST): A more efficient and sustained way the body generates heat involves specialised fat tissue called Brown Adipose Tissue (BAT), or brown fat. Unlike regular white fat which primarily stores energy, brown fat is packed with mitochondria (the powerhouses of cells) and is specifically designed to burn calories (from stored fat and glucose) to produce heat directly. Cold exposure is a key activator of brown fat. Research suggests that regular exposure to cold might even encourage the body to develop more of this metabolically active tissue.

Clarifying the "Slowing Metabolism" Aspect

The idea that extreme cold slows metabolism generally refers to situations of prolonged, severe cold exposure leading towards hypothermia. In such dangerous circumstances, the body's core temperature starts to drop significantly, and as a survival mechanism, overall metabolic processes may slow down to conserve energy. This is distinct from the increase in metabolic activity associated with generating heat in response to moderate cold. Indirectly, people might also experience a slight decrease in overall daily calorie burn in winter if the cold weather leads them to be significantly less physically active, but the direct physiological response to cold itself is typically to burn more calories for warmth.

Factors Influencing Calorie Burn

The amount of extra calories burned in the cold isn't fixed. It depends on the intensity and duration of the cold, the amount of protective clothing worn (insulation reduces heat loss and thus the need to generate extra heat), individual body composition (including the amount of brown fat), and acclimatisation to cold conditions. Physical activity also generates significant heat, reducing the need for shivering or NST.

Understanding Temperature with OpenWeather

Accurately knowing the temperature is key to managing cold exposure effectively. Dressing appropriately for the conditions helps maintain comfort and prevents the body from having to work excessively hard (and burn excessive calories through shivering) to stay warm.

OpenWeather provides precise temperature data vital for this preparation. OpenWeather APIs, including those in our Current Weather and Forecasts Collection, offer detailed current and predicted temperature information for any location globally. This includes crucial metrics like the 'feels like' temperature, which accounts for factors like wind chill, giving a more accurate picture of how cold the conditions will actually feel on exposed skin. Access to reliable temperature data helps individuals make informed decisions about clothing, activity levels, and time spent outdoors during colder periods, supporting health and well-being throughout the year.

Understanding the nuances of how our bodies react to cold, supported by accurate temperature information from reliable sources like OpenWeather, allows us to better navigate the changing seasons and manage our health effectively.