'My mother-in-law has given a nickname to my baby son that really hits a nerve.'

Fatty. Fatty Boomba. Fatso. Piggy Fat-Fat.

They’re the sort of nicknames that would make you wince if you heard adults using them on each other. But how about when adults use them on babies and kids? How about if it was your baby, and the adult calling him “Fatty” was your mother-in-law?

It’s an issue that crops up regularly in online mums’ forums. One mum, NataSal, on whattoexpect.com, said she’d overheard her mother-in-law referring to her six-month-old son as “Fat Boy”. She said the nickname “hit a nerve” because of issues she’d gone through when she was younger.

“What the heck am I supposed to do with that? … I personally see a healthy-sized baby when I look at him,” she added.

Some mums who replied insisted that “fat” was a compliment when it came to babies.

“In my family, ‘fat’ chunky babies are considered desirable,” wrote Sravie. “The more rolls, the cuter!”

But others sympathised with her.

“My mum has been referring to my son as ‘Fat Boy’, too,” said justUsPlus2. “I’m going to say, ‘Thanks, fat grandma!’”

Another poster, SashaAMB, said her grandmother-in-law started calling her baby daughter “Fatso”.

“It took everything, and I mean EVERYTHING, not to unleash all holy hell on her,” she wrote. “I went on and on about girls and healthy self-esteem until she (temporarily) backed off.”

Personally, I didn’t have this problem when my kids were babies. In fact, I had the opposite problem. Both my babies were small and, at six months, showed very little interest in solid food. I stressed that they weren’t putting on enough weight, and when one member of my family said my daughter was looking a bit thin, I got terribly upset.

But the point is the same. No parent wants to hear anything negative about their child’s weight. Even when it comes from a doctor, it needs to be said sensitively. As much as people may believe that fat equals cute when it comes to babies, “fat” is such a loaded word, for people of any age.

Sure, a six-month-old isn’t going to understand what the word “fat” means. But it’s safer not to start with the “Fatty Boomba” and “Piggy Fat-Fat” nicknames at all, just in case they stick.

Researchers have found that comments made to young girls about their weight have a negative impact on their lives. A Cornell University study last year discovered that if women could remember hearing comments about their weight as children, whether positive or negative, they were more likely to weigh more as adults and be unhappy with their bodies.

A previous study, done by the University of California, showed that women who were told they were “too fat” as children – whether they were or weren’t – were more likely to grow up to be obese. So much for this idea that overweight people just need someone to point out their weight problem to set them on the path to skinniness.

Now that my kids are older – and a lot more interested in solid food – I find myself being super cautious with what I say to them about their weight or anyone else’s. I don’t want one offhand comment of mine to be the one comment that makes them obsess about their body.

It’s safer, really, not to use the f-word at all when it comes to people. Not even babies.

Do you think it's okay to call a child fat? Is there a difference between baby fat and a weight issue?