Lent, traditionally a time of self-denial and restraint, begins on Wednesday. But how hard is it to give up something and does it really do us any good?

This 40-day period, which represents the time Jesus spent in the desert being taunted by Satan, is a period supposed to be marked by prayer, good deeds and fasting. Meat in particular is proscribed. St Thomas Aquinas claimed meat contributed to seminal matter, which “when abundant becomes a greater incentive to lust”; so fish is the dish for Lent.

But even in the Middle Ages, people were finding excuses. That most unreliable of prelates, Gerald of Wales (the one who claimed he saw geese emerging from barnacles in the spring) pronounced that beaver tails, a medieval delicacy, were a bit scaly-looking, so they obviously counted as fish. Obviously.

Excuses aside, how hard is it to give up something for Lent? Professor Jane Wardle is the director of the newly launched Health Behaviour Research Centre at University College London and she’s very clear. “It’s very hard.” Part of the problem is that many of the things that we would like to give up – say chocolate – are linked to automatic behaviours. For instance, you get home and go straight to the fridge and pour yourself a glass of white wine; you finish a meal and immediately reach for a Hobnob; or you have a drink and automatically light a cigarette. “Routines and habits dictate what we do,” she says.

We think of habits as bad, but as far as your brain is concerned, habits are good. Because they are automatic, while they are going on, processing power within your brain is freed up for other more important things. It’s the reason you can walk and chew gum at the same time.

Or carry on a conversation while you are filling a kettle. But, to be effective processing releasers, habits have to be well ingrained.

Creating good habits takes months

In an experiment designed to find out what it took to build a new habit, Professor Wardle’s group got volunteers to try to adopt a new healthy habit – giving up slothful lounging at lunchtime, for instance, and taking a short walk. Or not eating biscuits with coffee. Every day, the volunteers logged into a website and completed a questionnaire as to what they had done and how easy they had found it.

How long did it take for their resolve to become a normal part of their routine? “We found it took a very long time – 70 days in fact, although for some it was shorter.” So Lent’s 40 days would be over and you’d be tucking into Creme Eggs at Easter and still be little more than halfway through the process of creating an automatic habit out of your good intent.

So what are Professor Wardle’s tips to help you to give something up? “Many behaviours are about context, so some forward planning may be needed to alter context and give you a better chance of success and, in this way, having a set date like Lent helps.”

So, if you always reach for the wine bottle the minute you get home, consciously give yourself some other brain-absorbing task to do when you get through the door. And for further reinforcement, Professor Wardle also recommends writing things down or saying them out loud: “I’ll go straight to the sitting room and do a Su Doku when I get home.”

It’s easier to give up heroin than nicotine

The Health Behaviour Centre is core-funded by Cancer Research UK and its researchers work in three specific areas: diet and weight; screening; and smoking. Robert West leads the smoking group. While we might joke that we are addicted to Hobnobs, nicotine is truly and ferociously addictive (far more so than heroin, in fact). For West, the keys to giving up smoking are emotion and identity.

“All behaviour is emotion not belief,” West says. “It doesn’t matter what you believe – for instance, that smoking is bad for you – unless your actions generate feelings, your attempts at giving up won’t work. As far as smoking is concerned, he takes a different tack from Professor Wardle about the usefulness of Lent as a hook. For him, setting a date smacks too much of prevarication and of not really being up for the challenge. He also points out that about 50 per cent of attempts to quit involve no planning. Curiously, perhaps, these are the attempts that are more likely to be successful in the long term.

Epiphanies – such as someone close dying of lung cancer – are more helpful in terms of giving up smoking, because they generate an emotional surge. But emotion such as fear of lung cancer simply cannot be maintained at a constantly high level. A more successful way of sustaining emotion is through our own identities. Changing the way that we think about ourselves and the person we want to be – for instance, not a smoker but an ex-smoker – is important. In this way we violate our own identity if we resume smoking. Self-violation is aversive – a sort of self-imposed electric shock.

Stopping smoking is clearly beneficial, but what about changes in health habits for only 40 days? “It’s a kind of personal experiment which gives you good data about yourself,” says Professor Wardle. “It gives you feedback about how difficult or easy something will be, and you might then try another month.” Both experts point to the psychological value of imposing a regimen that gives you some measure of control in your life.

An inside look at addiction

Feel-good chemicals Dopamine is the brain chemical responsible for feelings of reward. Every time we think of our particular vice – be it cigarettes, wine or chocolate – dopamine generates sensations of relief and pleasure based on those we got the last time we indulged.

Getting hooked A further hit of dopamine occurs immediately after our first puff or sip, generating more pleasurable feelings, which reinforce the habit. This response takes place in the most basic part of the brain, the amygdala.

Psychological addiction Reward also occurs at a higher processing level, so it’s not surprising that there are multiple routes to kicking addictions, which include altering context, emotion and motivation.

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