“Judge not, lest you be judged,” so goes the popular Christian refrain. Less known, but equally striking is “Never trust a fat preacher.” Is it ok to judge if you’re a preacher? How can you guide your flock without making the judgement that they need guiding? If you do so judge, do you then have to be perfect to be a preacher? If you are not (and most of us aren’t) does that make you a hypocrite?

It’s a problem medics face as well. We give lifestyle advice to our patients. Don’t smoke, don’t drink, eat less, exercise more. And lets be honest, we often despair or ridicule if the patients don’t follow our advice as invariably seems to be the case. Are we in a position to do this? Before we say these things do we absolutely have to practise what we preach?

I don’t think so. I don’t smoke or drink excessively. This is not because I have sheer will power to overcome cravings: it’s just never been an issue. My favourite vice is food.

Two years ago I weighed nearly 16 stone. I wanted to lose weight, but I found it impossible. I craved all the food I knew had fattened me up to start with, and finding time to exercise was very difficult. At the beginning of this year I got lucky. I moved from a job starting at 8 in the morning to a job starting at 9. Suddenly, I had a spare hour. I started running. I started dating a slim vegetarian who loved cooking. My repertoire of healthy tasty meals grew. I stumbled across Paul McKenna’s I Can Make You Thin, which showed me how to stay positive, feel good about myself, and enjoy food in a natural way. I learnt to enjoy the richer foods as an occasional treat the way naturally thin people do. I lost 3 stone over 4 months.

When I changed jobs again I found I no longer had time to run in the mornings. After careful thought, I decided I should cycle to work.

7 months later, the weight is still off due to exercise and my new attitude to food.

Does this give me the right to sneer at fat patients who need their jaws wiring? Quite the opposite. I would never do this because I know how bloody hard it is.

You don’t have to be perfect to preach. You don’t even have to practise what you preach. But if you try, if you’ve been on that daunting journey to improve yourself, quashing doubts, working round pitfalls, starting up again after setbacks, you can tell patients what is after all the truth. Every one has flaws: some are unlucky to have flaws that can ruin their lives. We are here to help if they want to act. We will do everything in our power to stay positive. And we will not judge, lest we be judged.

Paul Vincent, F2 Microbiology, City Hospital, Birmingham