She liked me fat. It took a long time for me to understand that, and I think I came to understand it in a way she didn't.

It took me off the market, made me hers alone. And so she liked me fat.

It was a long relationship – seven years, near enough – and I wasn’t fat all the way through. There were times when I’d leave her alone in bed, pull on my runners, grab the dog, and head off for a long run in the park. The dog, at least, was there for me.

Oh, faithful hound, you were indeed my best friend.

It’s hard, though, nudging right up against impossible, when one person in a relationship isn’t merely indifferent about fitness and health, but actively hostile towards it. There were times when I gave up, and set about eating my frustrations. Those were the times I’d top out in the high 120s on the scales.

… while everyone gained weight as they got older, the waistlines of people with stressful, negative relationships ballooned more dangerously over time.

I was the dream subject for those research findings reported in Men’s Health earlier this year, the Northwestern University study which determined that while everyone gained weight as they got older, the waistlines of people with stressful, negative relationships ballooned more dangerously over time.

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I’m not blaming her. That would negate my own responsibility. She was who she was and I knew that about her. It was my own motivations and weaknesses I had to understand and correct before I could take control of my life, and that control did not magically arrive when I left her. It took some years, and the help of other people, other relationships.

We make ourselves fat, but often with the connivance of our friends, families and co-workers. How many times have you felt yourself judged and deprecated simply because you didn't stuff yourself to bursting point with gross tonnages of sugary carbs at some morning tea at work? Birthdays, retirements, days ending in the word “day” ¬– they’re all good for a pig out. Even blokes torching kilojoules and building muscle mass with hard physical labour do not escape, not when your workmates live on Mars Bars and Coke, and like to round out the day with half a dozen frosty ales.

The US, the land of the free and the home of the morbidly obese, is unsurprisingly the premium source of knowledge on how good behaviours, like exercise, optimism and maintaining a healthy diet, can pass from friend to friend like benign viruses. So too the reverse, with groups of friends infecting each other with obesity, depression and smoking.

The famous Framingham Heart Study, running since 1948 has monitored the health and fitness of over 15,000 residents of the small American town, tracking over the decades the national embiggening. (And also delivering the data which led to the discovery of “good” LDL cholesterol).

In the mid-noughties, a couple of social scientists took a run at the long data from a sociological perspective finding, as the New York Times reported, that “staying healthy isn’t just a matter of your genes and your diet, it seems. Good health is also a product, in part, of your sheer proximity to other healthy people.”

It’s another common-sense finding to throw in the face of fat activism – the perverse but understandable political movement to normalise obesity and even punish the efforts of those who try to avoid it. You are what you eat. To do is to be. And your fat friends are making you fat. It shouldn’t be a surprise. In the end we are social animals, and most comfortable with our own tribe, our own pack.

It can mean, though, that if you find yourself with the wrong tribe, the life changes demanded of you go far beyond buying a gym membership and cultivating a taste for kale. I know from hard, personal experience that I did not go lonesome into obesity. My recovery was likewise a team effort, even if I didn’t recognise it as such when I was grinding out the long miles on the treadmill before sun up, or trying to find enjoyment in a cup of green tea while all around me were drowning in mocha lattes. My wife, my doctor and, most unexpectedly, my blog buddies – many of them sliding towards midlife corpulence – were always there when I needed reminding why that sweet bakery treat was not my friend, or why a cold run on a wet morning was still immeasurably better than looking up at the same grey sky from a grave.

You might ponder this too if you’re at the start of a journey away from a life that’s killing you. You can’t do it all on your own. And you really can’t do it if you’re travelling with people heading in the opposite direction.

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