Take a look at the photograph above.

That’s me. About 16 months ago.

What do you see?

When I look at it now I see a man with haunted eyes who is thin. Painfully thin. Dangerously thin.

What is most scary is that I didn’t see that at the time. I looked at myself in the mirror every day and saw nothing wrong.

And yet people were warning me. Loved ones were telling me I had lost too much weight. Some people even asked if I had a disease.

And still I saw no problem. If anything I probably thought I could do with losing some more weight.

I don’t look like that now. My body, face and arms are a different shape. Much fuller. The pictures now tell a different story.

My brother showed me this photograph last week and it scared me. Not just because of my appearance but because of what it says of the remarkable capacity of the brain for self-deception.

How can you see that something is wrong when your brain projects a different image?

I should probably give some context. At the time I had just run a marathon. From having no athletic experience at all I trained obsessively for six months to complete the running challenge.

I was going through a tough time at work and my mental health was fragile. Looking back I clearly threw myself into a crazy training regime as some sort of diversion.

I was running six days a week. Getting up some mornings at 4:30am to do a 20 mile run before work.

But no matter how much I ran I could never shake the persistent feeling that I just wasn’t doing enough. My old friend the nagging doubt.

I also started doing strange things with my diet. I cut out gluten, dairy and sugar entirely. I lived on brown rice, nuts and canned fish for a long time.

I’ve always had a complex and difficult relationship with food. A troubling fascination about how my body will react when different things are put inside it. Or not.

This is woven into separate issues surrounding weight, body image and mental health. It’s such a difficult interdependency that I’m pretty confident I’ll never really understand it.

Or understand why it is that I do certain things.

As a young child I often remember being hungry. Where I grew up it was spuds for dinner every night. I was never too fond of potatoes boiled to the point of being almost souped so I sometimes went without.

We’d have a Rich Tea biscuit and a drink of water for supper but I often remember going to bed with a sore, almost empty stomach.

I think this drove in me a determination to be self-sufficient in the kitchen. I remember using the chip pan by myself when I was about eight or nine. Long before they were dangerous. But I had no proper understanding of food and no culinary skills.

Despite this I was a good eater. I loved school dinners and would gorge myself on the steamed puddings and thick custard that the other boys turned up their noses at.

Something changed when I was a student at Queens. At this difficult time some of my anxiety problems were beginning to manifest themselves.

I was becoming more and more conscious that my skeletal pale frame looked puny and absurd compared to most of my more muscular peers. I was very embarrassed about how I looked. I always assumed girls were laughing at my physique.

My diet lost all sense of structure. I found I had the capacity to go for long periods of time without food.

I never ate breakfast and very rarely dined during the days at all. Sometimes I would feast at night, having my first meal of the day at about 11pm. On other occasions I would not eat at all.

I also became aware of the first time of the link between food and what was going on in my brain.

For years I simply could not eat in the presence of other people, family and close friends excepted. My stomach would churn and my throat seemed to contract at the horrific thought of it.

This destroyed eating out as a social choice. I came to dread any situation where I had to eat in front of other people. Several times I had to invent lies about feeling ill to explain why I wasn’t having any food.

One year a close friend invited me to her house for Christmas. I shouldn’t have gone. Her mother plated a huge Christmas dinner which I couldn’t touch beyond moving the food around the plate pathetically with my fork. The mother looked horrified and I was humiliated.

It got so bad that on several occasions I found the only way I could stomach having food was when I was drunk.

But over the years things began to improve. In a sense.

As I started to assert my independence in life my interest in food deepened. I devoured cookbooks and taught myself the basics about how to prepare food properly and to make use of fresh ingredients.

My fears about eating out eventually melted away. I developed a love of the cafe and restaurant culture which remains among my dearest pleasures in life.

And so developed another problem.

I found that I couldn’t stop.

I simply didn’t possess the capacity to know when I’d had enough. The trigger in the brain which says stop just wasn’t working.

From the shy teenager who couldn’t eat a pick, I became a gorger.

In the morning I couldn’t stop at one bowl of cereal, I had to have four or five. If I opened a packet of biscuits then I wouldn’t cease until they were all gone in one sitting. I would buy a packet of six yogurts to last all week and then devour them all within minutes of getting home.

There was something about the way I ate as well. It was urgent. Like a force of nature not to be disturbed. I deplored people trying to talk to me as I feasted.

It could be quite embarrassing, if we were with a group in a restaurant. While all my peers were still stuffing their napkins into their shirts I was already finished and wanting more.

My wife also developed the habit of eating fast as well. For her it was an evolutionary defence against me stealing her food once I was done.

I existed on the edge of what is socially acceptable with food. I would ask others if they intended eating what was on their plate.

I stared longingly at the food on the plates of diners at other tables. I simply couldn’t comprehend that they could sit there chatting casually to each other while they hadn’t finished their food. It angered me that they could be so blasé about their meal.

It seemed absurd that society demanded that their leftover food should be binned rather than allowing me to walk over there and take it from their plates.

Some wives may suffer from husbands whose eyes are drawn to other women. Mine often had to tell me off for staring too obviously at someone else’s plate.

But the downside could be debilitating. The linkage of overeating with depression is well known. Often my most acute feelings of worthlessness came when I had eaten so much that I felt sick. I knew it would happen, I told myself to stop, but I just kept eating. Then I despised myself for the weakness.

But somehow I stayed slim. No matter how much junk I ate it never seemed to have any impact on my body weight or shape.

My thin frame, which had been a curse when I was a teenager, now seemed a blessing. I saw countless younger men’s bodies collapse into a middle-aged pear shape while I stayed relatively lithe and fit.

Well, for a while at least.

As I passed 40 things began to happen. There was hair on my body where it had previously been desert. My stomach, up to now admirably concave, collapsed into some sort of soft convex bulge.

So I decided to do something about it.

There comes a point in your life where you know you have to start looking after yourself. I also thought a fitter body would assist in combating my mental gremlins. It seemed to make sense.

Unless you’ve got a chronic depressive obsessive personality-type.

One of my first decisions was that I needed to drink more water. So I drank three litres every day. Exactly three litres. Every day. Not a drop more or less.

My wife bought me a watch with a step counter. I decided I had to do 20,000 steps every day. If it got to late in the evening and I was lagging behind I could be found walking incessantly around the kitchen table. I pulled all sorts of diversions to ensure that the step which took me into bed at night was my 20,000th.

Sugar, gluten and dairy were all binned from my diet. My kitchen cupboards were reorganised to be full of glass jars packed with nuts and seeds. Coffee was banned.

Just to offer some brief defence for my actions. I knew there was no point in me trying to cut down on something like sugar. The only relationship I have with sweet food is one of excess. The only hope I had was to banish it from the house.

And then there was the running. The endless hours of pounding the pavements.

I trained for the marathon through last winter, which brought a surfeit of nasty storms with names. I found myself running in the darkest, blackest mornings several times with gale force winds blowing sheets of stinging, icy rain straight into my face.

And yet I kept on going. I learnt that my willpower is like iron when I set my mind to a task. I was a victim of my own stubbornness.

And so I ran the marathon. In a decent time.

And then the photograph with which I started this blog post was taken.

Was I healthier than before? Perhaps in some ways.

However, my face looks haggard and drawn. The arms are skeletal. The torso so sickeningly thin.

But the real point is the look on the face. There’s no joy there. No love of life. There’s fear in the eyes.

Gradually I’ve drifted away from the fitness and dietary regime I set myself and my body is now pretty much back to where it was before I started.

I still eat way too much. I wish I could stop that.

I could probably do with losing a pound or two.

My son likes to make fun of ‘daddy’s big fat belly’ and plays a game where he slaps it repeatedly to watch it wobble.

Your physical health is like your mental health, it never stays static. There’s always a process of improvement or regression. You try to keep it moving in the right direction.

And you guard against the other. Because you don’t always see it in the mirror.