The ideal poo is a 'type 3' or 'type 4' – cracked or smooth sausage – delivered once per day.

Are you a three-times a day kind of person, or is a trip to the lavatory a more rare and special occasion? And crucially, what does your poo frequency reveal about your health? Sit down, relax, and learn about the science of poop.

How often we go for a number two can vary from person to person. Every time we eat, the large intestine contracts and pushes food along the digestive tract. This automatic "gastro-colic reflex" results in a the release of hormones that create the urge to poo, otherwise known as a "call to stool". Most of us have learnt to suppress this urge, however, meaning that once a day or less has become the new norm.

"We all tend to be too busy to poo," says Martin Veysey, a gastroenterologist and general medicine physician based at Canberra Hospital in Australia.

Conventionally, it has often been claimed that one poo a day is a sign of good gut health. But in the past it wasn't known what constitutes 'normal' when it comes to bowel movements. One study even implied that anything from one bowel action every few weeks or months to 24 poos a day could be regarded as normal.

However, thanks to the pioneering work of scientists like Ken Heaton, a consultant physician at the Bristol Royal Infirmary in the UK, we now known better. In the late 1980s, Keaton and colleagues surveyed residents of East Bristol, asking them the rather impertinent question – how often do you poo?

The results revealed a huge variety in bowel movements. Although the most common bowel habit was one poo per day, only 40% of men and 33% of women adhered to this practice. Some defecated less than once a week, others three times a day. Overall, the study concluded that "conventionally normal bowel function is enjoyed by less than half the population and that, in this aspect of human physiology, younger women are especially disadvantaged".

Incidentally this wasn't the only contribution Heaton made to the science of stools. He later helped devise The Bristol Stool Form Scale, which, with its accompanying illustrations, has become a widely used practical guide to help doctors diagnose digestive problems. The scale features handy descriptions of stools varying from "separate hard lumps, like nuts" to "fluffy pieces with ragged edges".

The NHS and other health bodies state that having a bowel movement between three times a day and three times a week is considered normal. But normal and healthy aren't necessarily the same thing. Scientists might have solved the mystery of how often we poo, but it does nothing to answer the question how often should we poo? Increasingly, researchers are finding that a person's bowel movements are a strong indicator of their health.

For example, a 2023 study examined the bowel habits of 14,573 adults in the United States. The most frequent bowel habit was seven times per week (50.7% of people), and the most common poo type was "like a sausage or snake, smooth and soft". Researchers then tracked the participants for over five years to see if there was any relationship between stool frequency and mortality. They found that people who pooed four soft stools a week were 1.78 times more likely to die within five years than those who pooed normal stools seven times a week. Infrequent defecators were also 2.42 and 2.27 more likely to die from cancer and cardiovascular disease, respectively.

How much is a good amount to poop is also a question occupying Sean Gibbons, a microbiologist at the Institute for Systems Biology in Seattle, the US. In 2024, Gibbons led a study which categorised 1,400 healthy adults into four groups based on their toilet habits; constipated........

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