can antibiotics cause weight gain

Can Antibiotics Cause Weight Gain?

Antibiotics are used at shockingly high levels for often trivial infections that would get better on their own, often without fully appreciating all the down sides. Like weight gain. Really? Can antibiotics cause weight gain?

Can Antibiotics Cause Weight Gain?



Back in the 60s and 70s scientists were researching how to make animals grow faster to cut down the time and cost to bring them to slaughter.

They found that adding a continuous low dose of antibiotics to the feed of almost any animal it dramatically increased it rate of growth and weight gain. (1)

But can antibiotics cause weight gain in humans?

There have been lots of studies on this over the years.

A really interesting one was done in Bristol in 2013, studying 12,000 kids from birth. (2) It was found that exposure to antibiotics in the first 6 months of life significantly increased the child’s body fat and their risk of obesity over the next 3 years.

These results were mirrored in a Danish study demonstrating the effect of antibiotic use in the first 6 months carrying on until 17 years old.

Just in case ‘sickly children’ were more likely to get fat than more robust kids who didn’t take antibiotics, research was done on mice. You guessed it – the antibiotic popping mice got fat.

Why Do Antibiotics Cause Weight Gain?

One of the most exciting areas of research right now is about the tiny organisms who live in our guts. Over looked, underappreciated, and unless you’re feeding yourself right – not fed properly either.

When you take antibiotics you don’t just kill of the bacteria you want to get rid of. You decimate the populations of friend bacteria in your gut.

Going back to the mice – after they were given antibiotics if was found that the diversity of bacteria in their guts had significantly reduced.

Damage to the gut flora as thought to be the driver in weight gain associated with antibiotic use.

Is Anyone Safe

If you’re one of those rarities who’ve never had a course of antibiotics in your life, don’t feel so smug just yet!

Next week I’ll write about how antibiotics are rife in some of the food you may be eating on a regular basis. But you’ll be ok with the suggestions on this list:

The Daily Checklist For Losing Weight

Have a great week!

Dr Julie

PS  Next time you visit your doctor and antibiotics are an option – have a chat about whether they are REALLY needed, or if you could safely wait to see if your illness will settle on its own.

If you really need the antibiotics – take step afterwards to help your gut flora recover.

  1. Visek, WJ, J Animal Sciences (1978) The mode of growth promotion by antibiotics
  2. Trasande, L, Int J Obes (Jan 2013) Infant antibiotic exposures and early life body mass
  3. AJslev, TA, Int J Obes (2011) Childhood overweight after establishment gut microbiota

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