I'm still short, still overweight. Turns out you can cure one but not the other. But over a six-year period, I've managed to keep off most of the weight I lost – and apparently that's unusual.

I'd like to thank the Live Life Well researchers at the University of Sydney's Boden Institute.

The particular researchers who found me six years ago were looking for a cohort of the overweight, under-exercised, overtired. They were assisted in their search by Dobber-In-Chief, my darling GP. Before I knew it, she'd signed me up for, among other far more useful things, a hideous focus group, all of us overeaters.

"I'm Jenna. And I eat too much." Kill me. I ditched the focus group because it made me want to tear strips off my flesh.

But I kept the rest: a nutritionist, an exercise physiologist, a food coach. That all sounds expensive but there are programs like this going on all the time and your GP can always hook you up. I didn't realise it at the time but you also have to be ready.

My metabolism turns out to be slow as a wet week so exercising meant I could eat more than two grapes and a celery stick – but the exercise isn't insane. And to be honest, gives you time away from the fridge. The exercise physiologist gave me things to do that didn't make me panic, walking, cycling, be active throughout the day. The nutritionist wasn't some health food nut, I could eat nearly everything in moderation. It was discovering what moderation really meant – and it wasn't three pieces of Toblerone every night.

Also vegetables. Eat them. They fill you up plus they stop you from being sad!

The best thing was the phone calls from the food coach who cheered when I lost weight, sympathised when I fell off the wagon – and revealed that a fresh date or two at night made you feel like you had eaten those pieces of Toblerone. She called me every week for a year. Some weeks I didn't want to answer the phone. Some weeks I wanted to ring her.

A year later, I'd lost a third of my bodyweight. A freaking miracle because I'd tried to lose weight over decades but never succeeded.

Less food, more water, much more exercise: you don't need a researcher to tell you that it works.

But what we do find from new research in this area – now underpinned by the Sax Institute's 45 and Up study led by Emily Banks, a professor of epidemiology and public health at ANU – are all the other reasons we need to keep a healthy weight.

So many.

Banks says: "For a lot of conditions, such as cancer and cardiovascular diseases, there is a big component of the risk that relates to weight and that is not offset by physical activity."

In short: you can be fit and fat but it won't stop you from getting cancer and heart disease or diabetes – all the diseases that killed my parents and my sister. Terrifying.

"In our research we found that those who were overweight had double the risk of developing diabetes – and those who were obese had five times the risk compared to someone of healthy weight," she said

"What was disturbing about the increase in risk – it was observed regardless of how much physical activity people did."

Get that? Your risk of diabetes increases with your weight. You can't fend it off just by doing a lot of exercise. I'd specially like to thank the researcher, Binh Nguyen, who found these convincing results through the 45 and Up study.

What I loved about the Live Life Well researchers was that no-one was interested in making me ashamed of being overweight. They all realise that it's more of a structural problem – and they are dead keen on finding a structural solution – or at least support for those of us who need it.

After the program, one of the researchers asked me to make a video about my experience. When she approached me, I felt tears running down my face. Because she knew it was hard. And it was. And it is. It will be. Those of you who are genetically slender have all the gifts. Not because you are gorgeous but because losing weight is hard.

You have to get your family on board (mine were lovely) and you have to get yourself on board, every single minute of every single day. It's a lifelong project.

And mine is to have a long life.