Katy Guest: Those pesky diet ads are as irritating as midges

I tried a little experiment on Facebook the other day. For two hours, I manically filled status updates with key words such as "real ale", "Wickes", "better composting" and "free curry". I hoped to provide bait for targeted advertising about which I might just give a monkey's. For half a day, ads trickled through for local carpenters, £5 off pizza, roofing materials, and a piano shop in north London. But by the following morning my ad feed was back to normal: "Lose 3 stone in 4 weeks", they kept telling me. "Win personalised M&Ms for your wedding."

Now that Facebook is a public company, I expect to see a lot more of these targeted adverts, so I'm trying to find a way of not being insulted every time I log on. I think that I have a pretty healthy body image, but there's only so many times you can be called a fatty before you start to take it to heart, especially when it's by firms who insist that they really do mean you personally.

Blocking the ads makes no difference: it's like trying to kill midges one by one. And only ads that break Facebook's guidelines will be removed from the site, its people tell me. That's because it supports free speech, which is good news.

The bad news is that relentlessly bombarding half the population with hectoring orders to get thinner does not break the rules. They also ban "misleading, fraudulent or deceptive claims" and insist on "proper grammar", which I love. But I don't understand how a diet that promises to evaporate three stone in a month is not either misleading or dangerous.

And it infuriates me that men I know are not targeted in this way. I asked my fiancé if Facebook has ever told him to lose a third of his body weight before he gets married, and he said that he just sees ads for cars, newspapers, adventure holidays and war games.

(How much would it cost me to send him ads telling him to shed three war games before our wedding, I wonder.)

I'm not opposed to advertising – it's what pays for Facebook, much of the internet, and newspapers. And I don't mind ads that target me based on my profile and activity. After all, what wedding would be complete without my initials on chocolate sweets?

What I do mind is receiving unstoppable weight loss bullying, just because I am a woman. That's not clever targeting; it's just rude.

Of course, the advertisers would not be paying Facebook to insult their users if all of this didn't work. Somewhere, there must be people clicking on the adverts and buying the products, whatever those products are. (And how much can you really charge for "no food", anyway?) And, since women are the ones being targeted, that must be because women respond.

So let me tell you this, reader. I have crunched your data, and I know this to be true: you probably don't need to lose three stone, and you definitely shouldn't do it within four weeks.

So how about we all ignore the diet bullies, and let the adverts for all the free curry get through?