I used to weigh 25 stone, but the responsibility for tackling the obesity crisis is yours as much as mine

Let's talk about what personal responsibility really means, and how you can make sure you're taking your own responsibilities seriously. Starting with not patronising your friend who would ‘be so pretty if they just lost weight’

I used to weigh 25 and a half stone. Thanks to weight loss surgery and the Slimming World programme, I am now around 13 stone – and aiming to make it to 10 and a half.

In my old life, I couldn’t walk 100 metres without crippling back pain. Last month I hiked 25km for charity, and up some pretty steep hills too. I have gone from being morbidly obese to obese. Soon, I hope, I will just be overweight.

And then, one day I will be a healthy weight.

In stating the science and calling for a ban on advertising junk food to children, Cancer Research UK is not fat shaming. Far from it; scientific truths are important and they can’t be massaged to spare the feelings of those who are affected by them.

That said, I've been there. I understand and share the pain of those who know that every time this debate is raised in public, no matter how sensitively by the charity in question, it will make life harder for those of us who are obese . These scientific facts will be translated through the lens the media, social media, and wider society put on them. That’s not CRUK’s fault, but it does need to be admitted.

Losing weight, even with the aid of surgery, is a physical and emotional slog. It's difficult in ways that people who only want to drop a few pounds for the summer will never truly understand. But because almost everyone has undertaken some form of weight control, everyone thinks they know how it is done. It is this that makes the myths around "personal responsibility" so prevalent.

Most obese people know that the ultimate formula for weight loss is to eat less and get more exercise. But that's just not as easy as it seems. Being obese doesn't just change your body, it affects your mind. Knowing the facts and being able to act on them are very different things.

When I was morbidly obese I was in constant pain and, like many people, I self-medicated. Very often, that was through the endorphin rush of overeating unhealthy food.

Food was, and is, my addiction. And unlike heroin, I can't just go cold turkey. Imagine being an alcoholic who has to keep wine in their house and drink a well-regulated portion of vodka every a day just to stay alive. That’s the level of challenge we’re talking about.

So before we hear it through the endless segments daytime television and rants from the likes of Piers Morgan, let's talk about what personal responsibility really means. Both from those who are obese and those who want to encourage them to lose weight.

Personal responsibility is about finding the right mindset before you do anything else. It's about making long term changes, not going on a diet.

One of the things I like best about Slimming World approach is that, though you count "syns" (and yes, I still cringe when I use that word), it isn't a diet. The emphasis in the group is on changing your relationship with food for life, not trying out ways of being that could never last. It’s one of the reasons that those who have achieved their target weight are encouraged to stay part of the group, and granted free membership to allow them to do so.

This is a lifetime change of behaviour and it needs a lifetime’s worth of support and encouragement, just as people in Alcoholics Anonymous are not thrown off the programme when they reach step 12.

From those who are not obese, but who are concerned about the obesity crisis, you too have a role to play in this challenge – it's just not the role you so often think it is.

Your personal responsibility is to not fat shame people on TV in the smug belief you're doing the nation a service. It's not to loudly comment on strangers who are just trying to get through their day. And it's definitely not to put patronising pressure on your friends who you feel “would be so pretty" if they just lost weight.

No, that role is about being understanding when your friend wants to meet in the same restaurant again and again, because she’s worked out what she can have there that works for her. It’s about changing your understanding of an obese person’s relationship with food, so you can support them in making better choices, not shame them into hiding their bad ones. It’s about understanding the emotions that go along with eating for a large portion of the population – and doing your best not to trigger those when you wade into this debate.

We all have a role to play in tackling the obesity crisis. As long as the sole burden falls on the fat, rather than looking at how societal attitudes are affecting them, the worse it will get.

So if you choose to fat shame off the back of this scientific research, please know that you are the problem. Just as much as the overweight, now it is time for you to have a sense of personal responsibility and understand the damage you are doing to society.