How eating too close to bedtime hurts your gut, heart, brain and weight

We know that eating a packet of crisps or a bowl of ice cream before bed isn’t great for our health, but avoiding those late-night snacks may be more beneficial than you realise.

A recent study found that avoiding food in the hours before you go to bed may help to stave off cognitive decline in older age. Researchers studied 47 overweight or obese women aged 50 to 79, all of whom were asked to reduce their diet by 500 calories a day for six months, with one group eating over a 12-hour period and another eating from 10am to 6pm.

Both groups lost an average of 7kg, but those who finished eating at 6pm performed better in spatial planning and problem-solving tests, with some evidence of improved memory and learning.

“This research adds to a growing body of evidence that the time of day that we eat our food matters as well as the eating window [the time between your first meal and your last],” says Sarah Berry, a professor of nutritional sciences at King’s College London and chief scientist at nutrition data company Zoe.

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Unfortunately, swapping biscuits or crisps for something healthier might not be enough. One study published in the European Journal of Nutrition , found that snacking late at night was associated with unfavourable health outcomes such as increased body fat and blood sugars, even if people were eating healthy snacks.

Eating four hours before bed (around 6pm) gives your body enough time to fully digest food, cool down and begin its reparative processes. “Our bodies are finely tuned to operate on a roughly 24-hour cycle called our circadian rhythm,” Prof Berry explains. “It governs all our bodily processes, from the gut to the brain and everywhere in between. Eating outside our natural rhythms is one of the primary reasons late-night eating can cause problems.”

Prof Berry explains the detrimental effects of late-night eating on our bodies, and shares her tips to minimise the damage.

As the recent study demonstrates, eating your last meal earlier could protect against cognitive decline. “Although there’s a limited amount of direct evidence,” says Prof Berry, “eating later in the evening might have a negative impact on brain health.” Eating later could disrupt the brain’s signals, disrupt our sleep and stress hormones, as well as increase inflammation in the brain.

Eating late is also known to disrupt your deep sleep, which is when our brains consolidate memories and clear out toxic waste that can lead to cognitive decline. However, deep sleep only occurs when the body cools sufficiently.