Emma Johnson, a make-up artist in her 20s, needed to take repeated antibiotics for painful and recurring urinary tract infections (UTIs) from the beginning.

Emma felt that the side effects of the antibiotics her GP prescribed were not only effective in fighting the infections but also led to weight gain.

Emma is 38 years old and believes that the seven-day, ten-year-long treatment with antibiotics has caused her to gain weight from 9st to 12, going from size 10 to size 16 in her 20s.

According to her, she normally consumed three meals per day and didn’t snack, however, when she started taking antibiotics, she became permanently hungry, feeling unable or unwilling to give in.

Emma, now 38, thinks the antibiotics she has taken for seven days at a time, ten times a year for around 18 years, were responsible for her weight ballooning from 9st to 12st

Emma now 38 believes the weight gain she experienced from her 9st to 12st due to antibiotics that were taken seven days a week for ten years.

‘The antibiotics always worked fast and gave me relief but I noticed a side-effect of desperate hunger. I couldn’t stop eating,’ says Emma, a mother of one from Dartford, Kent.

This is supported by evidence. One animal study in 2017 by the Liggins Institute at the University of Auckland, New Zealand, found that increasing use of antibiotics raised the risk of obesity — as well as affecting the body’s immune system or causing recurrent diarrhoea.

According to Gut, a 2018 study found that children who take regular antibiotics are more likely to become obese than their counterparts who don’t.

The seven-year study, looking at 333,000 children who’d been given any antibiotics in the first two years of life, concluded that early exposure to antibiotics altered their gut microbiome — the micro-organisms that live in our digestive tract, destroy harmful bacteria and produce important nutrients — and increased the likelihood of obesity.

Recent research suggests that gut bacteria could play an important role in appetite regulation (by altering signalling from the hormones that regulate it).

Emma had her first UTI at age 20 and then experienced multiple complications over the next year. She says that she felt a marked change in her appetite after she started taking the medication.

‘My stomach was always rumbling and I’d be constantly raiding the cupboards for snacks and wanting extra portions at mealtimes,’ she says. ‘It was all-consuming.’

‘The antibiotics always worked fast and gave me relief but I noticed a side-effect of desperate hunger. I couldn’t stop eating,’ says Emma, a mother of one from Dartford, Kent

‘The antibiotics always worked fast and gave me relief but I noticed a side-effect of desperate hunger. I couldn’t stop eating,’ says Emma, a mother of one from Dartford, Kent

Her hunger disappeared after just a couple of days. She was also losing weight, which is not surprising.

‘I started off as a size 10 before taking the antibiotics but I noticed that my clothes were tighter after a course,’ she says.

‘I lost the weight afterwards as my appetite reduced but sometimes my UTIs were close together — two or three weeks apart — meaning I was regularly restarting another antibiotic course, and gaining weight.’

The problem occurred even when on different types of the medication, and she ‘always ended up feeling desperately hungry’.

‘The hunger was so intense it was impossible to ignore,’ she says. ‘I even ate at night, standing in front of the fridge at 3am, eating whatever I could find.’

When she mentioned the weight gain to her doctor, he didn’t believe it was due to antibiotics.

And yet a possible link between weight gain and antibiotics first emerged in the early days of the drugs’ use. In 1951 researchers found that babies born prematurely in Italy received a daily dose (or more) of antibiotic chlortetracycline. After ten days, they were 8 percent heavier than those who were not treated.

A prominent American microbiologist, Dr Martin Blaser and his colleagues looked at the data of the Avon Longitudinal Study of Parents and Children (a UK ongoing project which began in the 1990s). They found that children who’d been given antibiotics during the first six months of life had become fatter than those who had not.

These findings led Dr Blaser, along with other researchers to conclude that antibiotics may have played a part in the rise of obesity around the world. What could be the link? The microbiome or gut bacteria.

Antibiotics can be dangerous because they not only kill the bacteria that causes illness but also harm those that help you stay healthy. If there is no balance in the microbiome, it can become chaotic.

This can affect levels of the ‘hunger hormone’ ghrelin — which is secreted in the stomach lining and sends messages to the brain telling you to eat. High levels of Ghrelin may also lead to fat storage.

‘We have bacteria everywhere in our bodies, and these work for our benefit by digesting foods,’ says Colin Garner, a professor of pharmacology and toxicology and CEO of Antibiotic Research UK. ‘But they can also be harmful, for instance when they cause infection.

‘Antibiotic treatment leads to a loss of diversity in gut bacteria, resulting in signals being produced in the gut to cause an increase in the ghrelin production by the stomach.

‘Ghrelin stimulates appetite and feelings of hunger, resulting in the individual eating more. It’s been known for many years that when antibiotics are fed to farm animals such as pigs, the pigs gain weight. It’s probable that the same thing happens in humans.’

Children generally have a balanced amount of good and harmful gut bacteria when they are born. Breastfeeding provides additional good bacteria.

Professor Garner says this helps to prevent them developing diabetes, obesity and other mental health issues later in life.

Wiping the good bacteria out with antibiotics can cause bad bacteria to dominate — and the good bacteria cannot then re-establish themselves.

‘As children’s bodies are rapidly developing, they are more susceptible to changes in the microbiome. This can have harmful effects in later life, such as obesity, diabetes, mental health problems, cardiovascular disease and irritable bowel syndrome (IBS),’ adds Professor Garner.

A single course of antibiotics may trigger hormone release, including ghrelin. Researchers have shown that animals can become obese by transferring bacteria from overweight people.

Professor Garner says: ‘Disturbing the equilibrium of bacteria through the killing effects of antibiotics will impact people in ways that cannot be predicted.’

Some people are not hungry, they feel the drug makes them so nauseated that it causes weight loss.

Professor Garner says we should curtail our use of these drugs: ‘Most healthy people can fight off infections without needing antibiotics.’

However, he said that some with chronic infections like Emma have no other choice. He suggests that those on antibiotics should focus on eating a healthy diet with plenty of fruit and vegetables, to help feed the ‘good’ micro-organisms.

Peter Whorwell is a Manchester University professor and consultant gastroenterologist. He suggests probiotics as an alternative to antibiotics.

‘In gastroenterology, we see a lot of problems following the use of antibiotics, and in IBS we see huge numbers who have their problems as a result of antibiotic use,’ he says.

He adds that it’s not narrow spectrum antibiotics, such as penicillin, that are the problem as these ‘kill only a couple of organisms’; it’s the broad spectrum ones ‘which kill everything in sight’.

‘Because the antibiotics have killed everything, it gives an opportunity for organisms which are not the best to have inside you an opportunity to grow.’

He argues that probiotics can be used to restore the health of a damaged gut. Studies back this assertion.

‘The problem is that probiotics vary from product to product, both in terms of the organisms and in terms of the concentration,’ Professor Whorwell says.

Emma tried other ways to prevent UTIs like cranberry juice but her UTIs returned and she was forced to keep taking antibiotics. 

She says: ‘They did help clear up my infections but they’ve definitely made me gain weight over the years’.

Clock Watching 

Your body’s power can be harnessed. The Week of the Dead: Turn off your smartphone 30 minutes before you go to bed

We’re often told that ‘blue’ light emitted from screens keeps us awake if used in the evenings, as this wavelength of light disrupts our body clocks.

Russell Foster, an Oxford professor of circadian neuroscience, says that blue light has a negative effect on light receptors, but it is unlikely to have any impact on sleep.

A 2014 Harvard University study which compared how long people took to fall asleep after reading an e-book or printed book found the difference was just ten minutes longer after using the e-book, which is ‘biologically meaningless’, says Professor Foster.

However, late-night use of phones, computers and other screens keeps the brain mentally active — which can stop us drifting off.

Professor Foster suggests that all electronics, including smartphones, be turned off 30 minutes prior to going to sleep in order to give your brain time for relaxation.