Ask the expert: Why winter slows digestion and spring supports balance

After what feels like months of short, dark, rainy days, the first shoots of spring are finally on the way. Chances are you’re delighted to put away your winter woollies and sit out in the evenings. But have you also noticed a change in your digestion? If you find bloating and constipation are less of an issue as spring comes around, you’re not alone. 

It’s well known that energy levels and mood can fluctuate with the seasons. Most of us have heard of Seasonal Affective Disorder or SAD, a condition that affects at least 1 in 20, and possible as many as 1 in 10 people in the UK. It’s a condition that causes symptoms similar to depression, usually worst in the depths of winter and lifting every spring. ‘Winter blues’ – a less severe version of SAD – affects as many as 1 in 5 people in the winter. 

But much else changes over the winter months. As winter draws in, your diet and activity levels often change – even without taking into account the excesses of the Christmas period. These, along with lower levels of daylight, can all contribute to a change in how efficiently your digestive system functions. 

Does digestion change with the seasons? 

You may not have given much thought to the link between your digestion and the seasons.  But the way food is propelled through your gut is profoundly influenced by many behaviours that can alter during winter. 

What you eat is fundamental to your digestive health. For instance, getting enough dietary fibre reduces the risk of constipation. Ultra-processed foods by contrast – low in nutrients and often high in additives, sugar, fat and salt – are low in fibre, lead to short-term sugar spikes (and the energy-sapping lows that follow them) and promote chronic inflammation.  

Exercise too is important for gut motility – and long nights and cold rainy weather are often a disincentive to get out and active. Importantly, both a poor diet and lack of exercise can have a negative impact on your gut microbiome – the huge community of bacteria and viruses that live in your bowels – which also contribute to sluggish digestion, bloating and inflammation. 

On the plus side, if your digestion struggles in the winter months, there’s a good chance that things will improve as your lifestyle shifts with the advent of spring. But there are also lots of changes you can make to guard against a return to bloating and sluggishness before the end of the year. 

Why digestion often slows down in winter 

Let’s drill down into some of the major seasonal factors affecting digestive health.  You may be falling into common negative habits in winter even without realising it. 

Lower physical activity 

Being active is about more than just exercising the muscles of your limbs – it also helps your gut propel food along your digestive tract in wave-like contractions, a process known as peristalsis. Not only does this process progress digested food from your stomach to your small and then your large intestine to be excreted – it also assists with the process of mixing food with your digestive juices and enzymes, assisting in nutrient absorption.  

Reduced activity can also decrease blood flow to the digestive system and alter hormone signals that support bowel movements. Food sitting in your stomach and small intestine, bacterial overgrowth can cause food to ferment early and release gas. And the longer digested food sits in your colon, the more water is absorbed, leading to harder, drier stools.  

Heavier, comfort foods 

In winter, your appetite-related hormones change. salads all too often lose their appeal – instead, we are conditioned to want warm, rich ‘comfort foods’. While for some of us, this means thick vegetable soups and bean stews, for many it translates into highly processed, carb-heavy foods. These are often high in unhealthy saturated fat and refined carbohydrates – bad for your bowels and for your gut microbiome. Perhaps not surprisingly, this change in diet also means average cholesterol and fasting blood sugar levels rise in winter as well. 

Winter mood and food 

Depression can affect your appetite in many ways: some people go off food completely, while others crave it, with changes in the brain affecting how pleasant food tastes and how it lights up reward centres in the brain.  

If you suffer from SAD or winter blues, you may experience many of the typical symptoms of depression – sadness, loss of enjoyment, excess sleepiness, irritability etc. But classically, SAD is linked to an increase in appetite and specifically to cravings for carbohydrate-rich foods and binge eating. Interestingly, while ‘carbs’ include both starchy (bread, pasta, pastry etc) and sugary (including sugary drinks and sweets) as well as a mix (cakes, biscuits etc) the main increase is in starchy carbs, with no change in protein intake. 

Reduced hydration 

While you may have heard a lot about the dangers of dehydration in summer, on average you’re likely to drink less water in winter. A significant proportion of fluid intake comes from food – and fruit and vegetables, often passed over in winter in favour of high-carb, refined foods – is lower in water as well as fibre. 

What’s more, central heating can have a significant effect on the atmosphere around you, drying out the air. This combination of lower fluid from food and drink with a dry atmosphere can make you prone to dehydration.  

Changes in light exposure and routine 

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Sleep and Circadian Regulation of Cortisol: A Short Review. Curr Opin Endocr Metab Res. (2021). Link. 

Depression-Related Increases and Decreases in Appetite: Dissociable Patterns of Aberrant Activity in Reward and Interoceptive Neurocircuitry. Am J Psychiatry. (2016). Link. 

Prevalence of seasonal affective disorder in primary care; a comparison of the seasonal health questionnaire and the seasonal pattern assessment questionnaire. J Affect Disord. (2004). Link.  

Circadian rhythms: a regulator of gastrointestinal health and dysfunction. Expert Rev Gastroenterol Hepatol. (2019). Link.