In my head I am thin. I just haven't quite got there yet. As I was growing up, it was made clear that the fat me wasn't welcome, that a thin person was expected and awaited, and impatiently so. Of my parents' four children, I was always known as the "fat one". They had longed for a girl, following two boys born in quick succession, and were thrilled when I finally arrived. As I well know, having longed for a daughter myself, when one dreams of having a girl one does not picture a fat one – no one does. Hopeful parents picture a sweet, pretty (regrettable, but true), adorable little thing who'll be cuddly and affectionate in the way boys, post-babyhood, are rarely expected to be.
As retold by my parents, their close friends and relatives, for the first few years I duly fulfilled the hopes and dreams they'd harboured when hankering for a daughter: I was cheeky, vivacious and "utterly charming". If the photos are anything to go by, I wasn't particularly pretty, and certainly not thin. I was a solid toddler, as one might expect since I'd weighed 11½ pounds (5.2kg) at birth. Clearly my personality made up for the fact that my looks weren't as fine as they might have hoped for. All well and good – except when I started to get plump at around nine years old.
I have no memory of suddenly eating more or exercising less; there is no logical explanation for the increase in size. I wasn't enormous, but I was plumper than my peers and my siblings, and this began to concern my parents greatly. I recall once complaining to my father about the discomfort I experienced when the tops of my thighs rubbed together, causing sore, red patches, to which he replied, characteristically obliquely, "Try pushing yourself away from the table." At the time, as children tend to, I took him literally.
On one memorable evening it was made clear to me I needed to deal with my weight and, moreover, that my parents found it intolerable. The whole family sat down for a supper of mince and mashed potatoes. (In itself this was memorable, since we very rarely ate all together. In the 60s, when I grew up, adults always ate separately, differently and inevitably better than kids.) Before we began eating, Dad stood up, looking a bit uneasy, cleared his throat and announced, "Arabella won't be having potatoes because she's fat." I remember feeling overcome with rage and indignation – why should I be punished for something that was out of my control? I only ever ate what my siblings ate. It wasn't my fault if my body processed it differently. I wasn't doing this on purpose to annoy my parents. However, it would appear this was exactly what my parents thought was going on. My oldest brother, Andrew, protested on my behalf, drawing attention to his own (albeit very slight) plumpness. "That's different, you're a boy," my father said.
Our parents were highly educated, left-leaning and shared many social values, including our mother's distaste for housewifery – while Dad expected to enjoy a well-run home, he did not expect it to be at the cost of Mum's intellect or sense of fulfilment – yet neither of them saw any paradox in separating a boy's physical requirements from those of a girl. The message was loud and clear: girls need to be pretty, boys don't.
Needless to say, neither of them then went on to educate me in the ways of dieting or exercising more. In order not to annoy them and be more lovable, I simply needed to be less fat. Unsurprisingly, this method did not work. I soon learned never to express hunger around them and to eat in secret, thereby developing an inextricable emotional link between what I ate and my ability to be loved. From then on, if I eschewed pudding, potatoes and biscuits in their presence, they were pleased and congratulatory – they did love me more. If I ate anything "bad" in front of them, the reaction was guaranteed: a flamboyant roll of the eyes, heavy sighs or loud cries of, "Do you do this on purpose to annoy me?" or "Have you any idea just how fattening that is?" My mother's favourite line was, "Watching you eat is like having hot knives stuck into my eyes!" The link between worthiness and abstinence – or, in reality, thinness – was unmistakably demarcated.
This belief has never been more evident than it is today. Society prizes a girl for being thin more than anything else she might bring to the table. With this pressure in mind, and acutely aware of the trap into which my parents had fallen (I know they loved me, but they also never denied loving me more the less I weighed), when I had children, I made a decision to avoid investing food and eating with anything other than love and ease. And that's when I found out that feeding your children is a minefield – much harder than one might think before becoming a parent and, I reluctantly admit, even harder if you have a girl when you yourself are a girl with "eating issues".
I'm not letting my parents off the hook, but I now know that attempting to nurture a healthy and relaxed approach to eating is hard. My parents' generation's benchmark was simple: Fat Equals Bad. These days not only do we have that message shoved down our throats, we are also bombarded with horror stories of child obesity and the huge rise in popularity of sedentary children's activities (favoured because they'll be abducted if they're allowed to play out, so we're led to believe), plus the five-a-day fruit-and-veg diktat. (I literally break into a sweat if their bedtime approaches and I've failed to meet the target – many is the night I've tried to persuade them to eat a selection of crudités in bed.)
Little wonder it's harder than ever to foster a stress-free approach to eating. And this is particularly true for women, to whom the relentless task of providing family meals almost always falls. Women are told we need to be thin to "count", while at the same time being charged with ensuring our children eat well but not too much; that a chocolate biscuit or two is OK, but eating the whole packet is not; that being skeletal is neither healthy nor attractive. Simultaneously, we must also aim to develop in them, the next generation, an egalitarian attitude to size and gender. It's a tall order. We have to be on high alert all the time.
I've got a boy and a girl; their parents are a boy and girl (me). The boys eat more than the girls, yet aren't overweight. My 11-year-old son never thinks about what effect eating might have on his body – if he wants something, he eats it. So far, food has no emotional value for him at all. And that's just how it ought to be. My daughter, who is 12, thinks about fashion as much as most girls of her age. She eats well and healthily, the same food as her brother, but less of it. Their father and I have avoided saying anything negative when more ice-cream, chocolate, biscuits, cake, is inevitably demanded. "Everything in moderation" is the aim; nothing is off limits, just the amount. So far, so good.
But I don't know what I'd do if one of my kids began to gain weight. Naturally I'd look to myself first, and check what and how much I was providing; but what if the weight gain was the result of food they were eating outside the home, for example, chips with their mates on the way home from school? In an ideal world, I'd bite my tongue and ride this phase out, hoping it was just that – a phase. During which a loving parent, desperately trying as I am not to attach any emotional value to food, is required to stand by and let their child make their own mistakes. But I can't say that would be right, either. I wish my parents hadn't made me feel that how I looked was linked to how much they loved me. But I do also see how hard it must be to see your child pile on the pounds and trust they'll find their own way back to a healthy weight.
Being able to be around food and never wonder if there'll be enough for you, never to worry if you'll be judged for what and how much you're eating – to be able to expect and enjoy good food and to feel entitled to it – is a fantastic gift. But, like any gift worth having, in the first place someone has to give it to you.
• The Real Me Is Thin, by Arabella Weir, is published by Fourth Estate, priced £16.99. Order a copy online for £11.99 with free UK p&p, at the Guardian Book Shop.