Antibiotics linked to childhood obesity

Joanna Scott-Lutyens BA (Hons) DipION

A study just published in JAMA Paediatrics has found that repeated exposure to broad-spectrum antibiotics from ages 0 to 23 months is associated with early childhood obesity.

a spread of different antibiotics

The study

This cohort study1 was carried out by US researchers from the University of Pennsylvania and Bloomberg School of Public Health. They reviewed the health records of more than 64,500 American children between 2001 and 2013. These children were followed up until they reached five years of age.

The findings of this study were that a huge 70% of them had been prescribed two courses of antibiotics by the time they were 24 months old. However, those who had had four or more courses of antibiotics were at a 10% higher risk of being obese at the age of five than children who had been given fewer drugs.

Additionally, it appeared that this correlation of obesity with antibiotics tended to be with those that were taking broad spectrum antibiotics rather than targeted antibiotics.

What does this mean?

As Dr Graham Burdge from the University of Southampton says, it’s important to point out this study doesn't mean antibiotics actually cause obesity, but rather that there may be an association between the two.

However, this is one of a number emerging studies suggesting a correlation between antibiotics and weight gain. There have indeed been other studies suggesting that some of the bacteria in our gut help fight weight gain and others, if they become pathogenic, will lead to a tendency to an increase in weight. 

We've written another article on gut bacteria and obesity, too. 

Another brand new study2 just published in the Journal for American Society for Microbiology found that a particular species of bacteria called Clostridium ramosum could promote weight gain in mice. The researchers found that the mice which had these bacteria in their gut and were fed a high fat meal became obese, whereas the mice who did not have these bacteria did not increase in weight on the same diet.

It is worth mentioning that as with most health issues it is difficult to prove a causal link as there are so many other variables in diet and lifestyle, and with human studies it is difficult and often unethical to try to isolate one variable. There is however strong, growing evidence to suggest that the microbiome plays a vital role in non-communicable health diseases, obesity being one of the most common of these. 

Prof Nick Finer, Consultant Endocrinologist and Bariatric Physician, University College London Hospitals, said:

 “This research on a large survey of children confirms previous findings that link early exposure to broad-spectrum antibiotics in children to obesity. The study suggest a dose response – i.e. the more exposure to antibiotics the greater the impact. While such studies cannot prove causation, the hypothesis that alterations in gut microbes happens as a result of broad spectrum antibiotics is plausible and fits in with much other research linking gut flora and obesity. The research provides another argument against unnecessary antibiotic use in children, although of course in children with serious infection antibiotics can be life-saving and in such cases should not be withheld.”

Can we do anything to support a child on antibiotics?

As we know there are times when taking antibiotics is necessary so is there anything we an do to protect our children’s microbiome in this situation? Taking probiotics, avoiding sugar in your diet, eating both probiotic and prebiotic foods are all recommended to boost your live gut bacteria. 

If you find the connection between antibiotics and obesity interesting, why not read our blog about bacteria and cravings


  1. L. Charles Bailey, Christopher B. Forrest, Peixin Zhang, Thomas M. Richards, Alice Livshits, Patricia A. DeRusso. Association of Antibiotics in Infancy With Early Childhood Obesity. JAMA Pediatrics, 2014; DOI: 10.1001/jamapediatrics.2014.1539
  2. Anni Woting, Nora Pfeiffer, Gunnar Loh, Susanne Klaus, and Michael Blaut. Clostridium ramosum Promotes High-Fat Diet-Induced Obesity in Gnotobiotic Mouse Models. mBio, September 2014 DOI: 10.1128/mBio.01530-14
  3. 2020. Science Media Centre. [online] Available at: <> [Accessed 5th Jan 2014].