Why do I feel tired after eating?

Is it normal to feel tired after eating?

Feeling drowsy after a meal, especially a large one, is not uncommon. In fact, up to 20% of people report experiencing what is known as a ‘food coma’ after eating. The medical term is post-prandial somnolence or post-prandial fatigue.

Symptoms include sleepiness, low energy levels, problems concentrating and lack of focus. The exact cause is not fully understood but there are several theories.

One is that is it’s your body’s natural response to digestion. After eating, the body redirects blood flow to the digestive system, this temporary shift in blood away from the brain can leave you feeling tired and sluggish. Another explanation is that we are programmed to feel sleepy after eating. In prehistoric times, as soon as our ancestors had caught and eaten food it was time for them to sleep, so it could well be a throwback to this.

Are some foods more likely to cause tiredness?

It seems that certain nutrients in foods are more likely to cause sleepiness. Eating a meal that's high in sugar or refined carbs – that's white bread, rice and pasta, as well as biscuits and cakes – causes blood sugar levels to spike, triggering the release of insulin as it moves sugar from the bloodstream into cells for energy. A rapid rise of insulin followed by a sharp decrease may lead to fatigue.

High-carb meals also release the amino acid tryptophan into the blood, increasing the release of serotonin in the brain, a hormone which induces sleep. Some protein-rich foods like turkey, chicken, eggs, cheese, fish, nuts and seeds are naturally rich in tryptophan. Without carbs, the tryptophan will not be well absorbed, but when eaten alongside carbs, more tryptophan is absorbed, making us sleepy.

The size of the meal eaten also has an impact on how you feel afterwards. Eating a large meal can cause sluggishness as the body needs to work harder to digest it, which leaves you feeling tired. Research into the sleep patterns of fruit flies reveals they were more likely to sleep after a large meal compared with a small one.

Misbah Ameen, Registered dietitian and spokesperson for the British Dietetic Association says that high-fat meals are more likely to make you feel sleepy and the time you eat can also have an effect. The body’s circadian rhythm – the internal clock which regulates sleep patterns – naturally takes a dip in the afternoon. If this happens when blood is being diverted from the brain to the digestive system, you may notice a strong desire to sleep.

Misbah goes on to say that you’re more likely to feel sleepy after lunch if you haven’t slept well the night before. This is because hormones that regulate your appetite are influenced by a lack of sleep, so if you're tired you're more likely to crave sugary foods and overeat. If post-meal fatigue is a regular problem, Misbah recommends keeping a food diary to help you identify your problem foods and eating patterns.

How to prevent food coma

1. Get some fresh air or go for a short walk outside after eating. This can aid digestion, improve blood flow, and help stabilise blood sugar levels. Natural day light can also help increase alertness and mental function during the post-lunch dip.

2. Avoid large meals: eat little and often, instead of three large meals, try eating smaller portions more frequently throughout the day. This can help maintain steady energy levels. Be mindful of portion sizes, especially when it comes to carbohydrates and fatty foods

3. Choose wholegrain carbs over refined. Wholegrain and low GI carbs help stabilise blood sugar levels and provide sustained energy.

4. Skip the carbs at lunch. Choose protein combined with veg instead, like an omelette with salad rather than scrambled eggs on toast.

5. Stay hydrated – even mild dehydration can exacerbate feelings of fatigue, so stay well-hydrated throughout the day

6. Eat regularly and avoid eating late at night – skipping meals will increase the risk that you over eat when you do eat and eating later at night can interfere with your qualify of sleep.

Health conditions that may cause post-meal fatigue

While feeling a bit tired after eating is normal, excessive fatigue could be a sign of an underlying health condition:

• Diabetes or prediabetes may cause someone to experience blood sugar fluctuations after meals which can cause fatigue
• Food intolerances or allergies can cause fatigue and other symptoms after eating certain foods. Keeping a food diary will help you to identify problem foods
• Anaemia – lack of iron or vitamin B12 can contribute persistent tiredness
• Hormonal issues such as an underactive thyroid can affect energy levels and metabolism

So, is feeling tired after eating normal?

While it's normal to feel a bit sleepy after eating, it's important to understand the factors that contribute to post-meal fatigue and make small adjustments to your eating habits, to help maintain energy levels throughout the day.

If you're consistently feeling exhausted after meals, talk to your GP or a registered dietitian. They can help identify any potential health concerns and provide personalised advice on optimising your diet for sustained energy.

Now try...

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Fiona Hunter, Bsc (Hons) Nutrition, PG Dip Dietetics, is a highly experienced nutritionist, having worked in the NHS and now as an independent nutrition consultant.

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