A study published in JAMA pediatrics on 29/09/2014 has found further evidence for an association between the use of antibiotics in infancy and early childhood obesity.

The study, conducted in North America showed that children who received broad-spectrum antibiotics (these kill a very wide range of bacteria) were 1.11 times more likely to be obese than those who had not been exposed to antibiotics.

This is not really new as a number of studies in the past have found similar associations, though this is one of the largest of its type.  As a quality paper in a prestigious journal, it seems reasonable to say that the use of some antibiotics in infancy is indeed associated with a small risk of obesity in early childhood.

Sadly, though we try very hard to avoid prescribing antibiotics, sometimes the benefits outweigh the risks and we have no choice.  We help by trying hard to give your child the least harmful antibiotic that is likely to work.

Why might antibiotics cause obesity?

Without exception, in every single case, obesity is caused by an excess of food.  More calories are consumed than are used and this leads to weight gain as the spare calories are stored as fat.  Where bacteria play a role is in the 'peanut effect' - it takes only a peanut a day more than you need to gain half a kilo in a year.  Tiny levels of calorie excess add up over time.  Bacteria secrete enzymes that may help to make some foods very slightly more digestible than might otherwise be the case and it is thought that if the effect seen with antibiotics is genuine, it may be due to the drugs favouring the growth of these same bacteria over others.  This may lead to more efficient use of food and in fact, the plausible energy gains are actually enough to account for the observed weight gain.

Is the case against antibiotics proven then?

No, of course nothing is that simple in medicine.  Children are more likely to need antibiotics to treat illness if they have not been breast fed, are kept in overcrowded environments, are kept in overclean environments, have financially disadvantaged parents, have parents who are less well educated, live in an urban environment or have asthma all of which are themselves associated with a higher risk of obesity whether or not antibiotics have been prescribed.  It is far more likely that these are the cause of the problem than the antibiotics.

Should I give my child probiotics?

There is good short term evidence that probiotics may reduce the severity of antibiotic induced diarrhoea and no evidence of short term harm, but there have been no studies investigating whether or not they reduce the risk of obesity.  It is quite plausible that they may actually increase it by affecting gut micro-organisms adversely - the short answer is, we don't know but it's almost certainly not going to alter your child's weight.

How do I stop my child becoming obese?

It is a matter of accepting completely and without doubt that children who are overweight are overfed.  If your child is obese it is because you are giving them more food than they need for the level of exercise they are getting.  Even if the association with antibiotics is genuine, that does not alter this simple fact.  If your child seems overweight then you need to do something about it.  

Do remember that children under two are supposed to be quite chubby and this reduces until by the age of 6, they should have very little fat at all.

It is ALWAYS acceptable to encourage children to excercise.  Young children should be encouraged to run and play every day until they can do no more.  Fitness is critical to later health and it starts with ensuring your young child enjoys exercise and gets a lot of it.  Parents with very fit children also find they have far fewer discipline problems so it's a win-win if you get your child running.  

Restricting a child's diet is a much harder thing to do safely and outside the scope of this article - our nurses will happily weigh and measure your child, listen to your particular circumstances and help you to manage your child's weight safely.  There is no charge for this service for enrolled children.  We will be publishing articles on child nutrition in the next few months.

Credits:

Obese child:  Miran Rijavec

Peanuts:  cbertel