There is a rule when it comes to the internet: if you can think of it, then it probably already exists. There are thousands of strange and brilliant blogs and Facebook groups to prove the theory. Things like Selleck Waterfall Sandwich – a photo-based blog on the popular hosting site Tumblr that consists simply of photos of Tom Selleck, photoshopped on to a backdrop of waterfalls, with a sandwich. Or Awesome People Hanging Out Together – an online collection of photos capturing brilliant or unlikely meetings between celebrities such as David Bowie, Michael Jackson and Bette Midler, on a bench.

So far, however, there is no famous blog called Men Who Eat In Ford Transits. Nor is there a hugely popular Facebook group called Men Eating Chicken On Night Buses. And I am yet to find a website dedicated to photographs of Men Who Eat Boots Meal Deals On Trains. Yet Women Who Eat On Tubes has 15,400 members and counting on Facebook. The David Bailey fan page has, by contrast, just 1,782.

For those of you who haven't seen this latest example of public transport trolling, allow me to explain. Women Who Eat On Tubes is an open Facebook group where people post full-frontal pictures of women eating on the London underground. So far, so invasive. What tips the balance just that little bit further is that the photographers also upload the time the photo was taken, the food the woman was eating and the tube line that she was travelling on.

I have huge reservations about people taking photos of strangers on trains in the first place. Particularly when those people are made easily identifiable and the subject of anonymous, derisive, malicious humour. But this group sticks in my gullet for other reasons.

Firstly, Women Who Eat On Tubes highlights, once again, that age-old, tiresome comparison between sex and food. I hate that plus-size models are so often photographed chewing on bloody steaks or drizzled in honey. It is exasperating beyond words to be leered at by sweaty idiots when I'm seen eating anything that's even tenuously phallic. And I find it more than faintly offensive that women are told that greed, sensual pleasure and appetite are unladylike, unfeminine and unattractive.

It doesn't take a Freudian to tell you that the act of watching something get pushed into an orifice can have vaguely sexual overtones. Which is why being photographed while eating, and without your knowledge or permission, does feel invasive. It feels like voyeurism.

I don't think we should follow Hungary's model and make it illegal to take a photograph without gaining the permission of everyone in frame, but the trend towards photographing strangers feels like a loss of social decency. We are losing our grip on what it is to be human. We are forgetting that other people have feelings too. By putting a smartphone between us and our carriage companions we have stopped seeing them as individuals and started seeing them as fodder for that most unappetising of all things – social-media banter.

Finally, as someone who relishes eating whatever I want, wherever I want, whenever I want, I hugely dislike the fact that women eating on the tube is even seen as noteworthy. To enjoy food alone and to eat without shame are vital parts of becoming self-sufficient. And self-sufficiency is the surest path to unshakable happiness.

So, what is the answer? Sophie Wilkinson, a journalist, discovered a photo of herself uploaded to Women Who Eat On Tubes last week. After emailing the photographer, complaining to Facebook and approaching Transport For London, Wilkinson's attempts to address the situation were frustrated by the fact that to take photos of strangers on the tube is not illegal. While it may cross the boundaries of what we consider socially acceptable, taking a secret snap of a woman on the Northern line does not break the law. There was, in short, little room for redress.

If confronting the people who run, submit to or follow the blog doesn't work, what are our options? Well, walking or cycling to work would be one solution, of course. Also, dare I say it, if we all engaged in a little more social interaction on public transport then perhaps then we would start to see each other as people, and not just orifices to be ridiculed.

But perhaps, most of all, we need to address that eating-woman-as-sexual-object cliche. Just because a woman is thrusting an object into her mouth does not mean she deserves to be the subject of titillation. It's crass, boring and reductive, and says much more about the photographer than it does the subject.

Women need to eat. All those hundreds of daughters, mothers, colleagues, friends, sisters and bosses munching and making their way through London on the tube are people, just like the Ginsters-eating man in his white van. They do important jobs, they make useful things, they have interesting things to say, they have people relying on them and they cannot cope with all that on an empty stomach.

So stop looking at women through the lens of your smartphone and snide sense of superiority. And simply leave them to their snacks.