Why Does Appetite Increase in Cold Weather?
In this article
The Neurobiology of Thermoregulation and Energy Balance
The irresistible urge to eat that you feel in winter or when the weather suddenly turns cold is not simply “weak willpower” or “boredom.” It is a complex survival mechanism encoded in our genes through millions of years of evolution, operating according to the fundamental laws of Thermodynamics and governed by the Hypothalamus . The body mobilizes its metabolism to maintain internal balance (homeostasis) as temperatures fall. Below, you can find full details of this neurobiological process.
1. The Cost of Thermoregulation: Producing Heat Is Expensive
The human body is homeothermic; whether the outside temperature is -10°C or +40°C, it must keep the internal temperature at which vital organs function (Core Temperature) steady at 36.5°C - 37.5°C . When cold stress threatens this balance, the body must “turn on the heaters.” This happens through two main pathways:
- A. Non-Shivering Thermogenesis: The sympathetic nervous system activates as soon as cold is detected. A special tissue that acts as the body’s “stove,” Brown Adipose Tissue (BAT) , comes into play. Through a protein called UCP1 (Uncoupling Protein 1) , mitochondria in this tissue convert energy from food (ATP) directly into heat energy rather than chemical energy. This is biologically very costly and rapidly consumes blood glucose.
- B. Shivering Thermogenesis (Shivering): When body temperature falls further, skeletal muscles begin contracting rapidly and involuntarily (shivering). This mechanical work can increase the metabolic rate to up to 5 times normal . This intense muscle activity rapidly depletes glycogen stores.
More heat production directly means more calories burned. The brain sends an urgent “REFUEL” signal to replenish depleted energy stores (glycogen) and replace burned fat. This creates intense hunger.
2. Neuroendocrine Response: The Battle of the Hormones
Increased energy expenditure sends biochemical signals to the brain. This signaling occurs within the brain’s appetite control center, the Hypothalamus, in its Arcuate Nucleus region.
| Hormone | Change and Mechanism of Action |
|---|---|
| Ghrelin (Hunger Hormone) | Released when the stomach empties and body temperature falls. It travels through the blood to the brain, stimulating the Hypothalamus and triggering release of NPY (Neuropeptide Y) and AgRP . These two agents give the brain its most powerful “eat” command. |
| Leptin (Satiety Hormone) | Normally released by fat tissue to say “I’m full, stop,” Leptin is ignored by the brain in cold weather (Leptin Resistance). The body suppresses satiety signals because it wants to preserve fat tissue for insulation. |
| Cortisol (Stress Hormone) | Cold weather is a physical stressor for the body. This stress triggers Cortisol release from the adrenal glands. High cortisol particularly increases cravings for “sugary and fatty” foods. |
3. Winter Blues, Carbohydrates and Serotonin Balance
Reduced sunlight in winter directly affects not only vitamin D, but also brain chemistry. In the literature, this is described as neurochemical changes associated with Seasonal Affective Disorder (SAD) .
🧠 The Brain’s Attempt to Produce “Its Own Medicine”:- Serotonin Decline: Serotonin is the neurotransmitter responsible for happiness and well-being. When sunlight decreases, serotonin production in the brain falls. This makes people feel more depressed, tired and unhappy.
- The Role of Insulin: The body takes an interesting route to increase serotonin. Its building block, the amino acid Tryptophan , needs Insulin to enter the brain.
- Carbohydrate Cravings: Eating carbohydrates (pastries, sweets, pasta) raises insulin. High insulin facilitates tryptophan’s entry into the brain and provides a temporary serotonin increase (relief).
- Result: Reaching for sweets almost involuntarily on cold, dark days is actually the brain’s attempt at self-medication.
4. Evolutionary Perspective: “Scarcity Is Coming”
Summary and Clinical Implication
Increased appetite in cold weather combines three main factors:
- Physiological: Increased calorie requirements to maintain body temperature (Thermogenesis).
- Psychological/Neurological: An attempt to compensate for falling serotonin caused by reduced daylight.
- Evolutionary: The instinct to store fat, triggered by fear of scarcity.
During this process, prioritizing protein in the diet, having vitamin D levels checked and choosing complex carbohydrates may help manage this biological drive.
Scientific References
- Cannon, B., & Nedergaard, J. (2004). "Brown adipose tissue: function and physiological significance." Physiological Reviews, 84(1), 277–359.
- Klok, M. D., et al. (2007). "The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review." Obesity Reviews, 8(1), 21–34.
- Wurtman, R. J., & Wurtman, J. J. (1995). "Brain serotonin, carbohydrate-craving, obesity and depression." Obesity Research, 3(S4), 477S-480S.
- Tups, A. (2009). "Physiological regulation of food intake and energy balance by temperature." Physiology & Behavior.
Was this article helpful?
Your feedback helps us improve our content.
Reader comments
Share your comment
Your name and comment are published only after administrator approval. Your email address is never shown to visitors.
Be the first to comment.