Why does digestion often feel slower in winter?

As winter arrives, many people notice a familiar discomfort: bloating after meals, constipation, reduced appetite, or a lingering heaviness in the stomach. While these symptoms are often brushed off as seasonal inconveniences, science offers clear explanations for why digestion tends to slow down during colder months. 

At its core, digestion is an energy-intensive process that relies on adequate blood flow, muscle contractions, enzymes, hormones, hydration, and physical activity. Winter alters several of these factors simultaneously, creating a perfect storm for sluggish digestion.

Reduced blood flow to the gut: One of the body’s primary responses to cold is vasoconstriction, the narrowing of blood vessels. This helps conserve heat by prioritizing blood flow to vital organs such as the heart and brain. As a result, peripheral areas, including the gastrointestinal tract, may receive comparatively less blood. Reduced blood flow can slow gastric emptying and intestinal movement, leading to feelings of fullness, indigestion, and constipation. 

Lower physical activity levels: Physical activity plays a crucial role in stimulating gut motility, the rhythmic contraction of intestinal muscles that move food along the digestive tract. In winter, people tend to move less due to shorter daylight hours, colder temperatures, and lifestyle changes. Even a modest reduction in daily walking can affect digestive efficiency. 

Changes in hydration status: Cold weather often suppresses thirst signals. People drink less water in winter compared to summer, even though the body continues to lose fluids through breathing and urine. Inadequate hydration leads to harder stools and slower intestinal transit. The colon absorbs more water from stool when fluid intake is low, making bowel movements infrequent and uncomfortable.

Dietary shifts and fibre intake: Seasonal eating patterns also influence digestion. Winter diets often include more refined carbohydrates, fried foods, meat-heavy dishes, and fewer raw fruits and vegetables. While warm, energy-dense foods provide comfort, they are often low in dietary fibre.

Hormonal and circadian influences: Winter affects circadian rhythms due to reduced sunlight exposure. Disruption of the body’s internal clock can influence digestive hormones such as melatonin, cortisol, and serotonin. The gut-brain axis, an intricate communication system between the digestive system and the nervous system, plays a role in regulating appetite, motility, and enzyme secretion. Altered sleep patterns and seasonal mood changes can indirectly impair digestive function. 

Reduced exposure to sunlight and vitamin D: Lower sunlight exposure during winter months can contribute to vitamin D deficiency, which is increasingly being linked to gut health. Emerging research suggests that vitamin D plays a role in maintaining intestinal barrier integrity, supporting beneficial gut bacteria, and regulating inflammation. Although research is ongoing, inadequate vitamin D may contribute to digestive discomfort and altered gut motility.

Psychological stress and winter blues: Mental health and digestion are deeply interconnected. Seasonal affective symptoms, increased stress, and low mood during winter can activate the body’s stress response. Elevated stress hormones such as cortisol can slow digestion by shifting the body into a “fight or flight” mode, where digestion becomes a lower priority.

What can be done? While winter-related digestive slowdown is common, it is not inevitable. Maintaining regular physical activity, ensuring adequate water intake, prioritising fiber-rich foods such as vegetables, legumes, and whole grains, and establishing consistent sleep routines can significantly support gut health. Warm meals, herbal teas, and mindful eating may also improve digestive comfort.

The writer is the founder & CEO of Nutrition For Change. E-mail: raisameh20@gmail.com