In a world where you can inhale half your daily allotment of kilojoules as you turn left out of the drive-thru, often the only thing standing between you and a few extra chins is willpower - that oh-so-elusive ability to halt the urge to indulge. If your powers of resistance are lacking, you'll be psyched to hear this: research shows that willpower is a kind of mental muscle, and like any other muscle, it can get stronger. These four tactics target the most common resolve busters. Put them into practice, and pretty soon that cheesy pizza slice or glazed doughnut will be no match for your mighty mental strength.

1. Eat smaller, more frequent meals

What it targets: An out-of-control appetite
Why it works: Going for too long without eating makes your blood sugar plummet. That leaves you with a raging appetite that can overpower your best intentions. If you have small meals every three to five hours, your blood sugar stays stable, preventing a sugar low that will leave you vulnerable to overeating, says dietitian Lisa Jones.

Your blood-sugar levels do more than affect how hungry you get; they're also directly connected to willpower. In lab studies, people's blood-sugar levels dropped when they performed self-control tasks; then, when asked to attempt another test of resolve, they fared worse. Raising blood glucose with sugar-sweetened drinks restored the subjects' lost willpower. "Mental tasks, such as self-control or concentration, require the same energy your body runs on," explains Dr Roy Baumeister, a professor of psychology at Florida State University, US, who conducted the studies. "So it will be harder to exert willpower if you haven't had enough to eat."

Your weight won't take too kindly to your downing sugary drinks, so reach for snacks that mix carbs with lean protein and a bit of healthy fat (the kind found in nuts, olive oil and fish) to keep your blood sugar on an even keel. Try low-fat yoghurt with berries, or a handful of almonds with an apple.

2. Eat with your other hand

What it targets: Distraction
Why it works: Picking up a fork with the hand you don't usually use automatically slows you down and makes you focus on your meal - two things that have been proven to aid weight loss. Now studies are showing that, with regular practice, this kind of switcheroo technique can also increase your overall willpower. Dr Baumeister found that people whose resolve was drained by one test - say, resisting a bowl of delicious, crispy hot chips in favour of a plate of boiled brussels sprouts - gave up more quickly on consecutive tests, such as trying to solve an unsolvable puzzle. But in another of Dr Baumeister's studies, when subjects spent several weeks practising small acts of self-control, such as using a different hand to brush their teeth or operate a computer mouse, they worked longer on that same puzzle.

"By practising their ability to override one specific impulse, they increased their overall capacity for resisting impulses," Dr Baumeister explains. The subjects in this study saw signs of progress within three weeks of daily activity. Of course, your results will depend on how often you practise and whether you keep it up over time - it's quite possible that, just like your upper arms, your grey matter can turn flabby if you don't keep working it out on a regular basis.

3. Be realistic about your willpower

What it targets: Impulsive eating
Why it works: Most people overestimate their ability to resist temptation, according to new research from the Kellogg School of Management, Northwestern University, in the US. Researchers found that when participants were in a "cold state" (ie, not experiencing hunger or other cravings) they had a hard time understanding how a "hot" impulsive state will influence their behaviour. "People are not good at anticipating the power of their urges, and those who are the most confident about their self-control are the most likely to give in to temptation," says Professor Loran Nordgren, who led the study. "The key is simply to avoid any situations where... weaknesses thrive and, most importantly, for individuals to keep a humble view of their willpower."

Staying "humble" might include arranging lunch with friends in a sushi bar rather than a pizza joint; or resisting the purchase of a jumbo tub of ice-cream that you're confident will last for weeks. As Dr Baumeister says, self-control is a limited resource, so giving yourself fewer opportunities to resort to it can only be a good thing.

4. Lift your spirits

What it targets: Emotional eating
Why it works: It's estimated that when people overeat, nearly 75 per cent of the time it's because they're feeling down. It stands to reason that lifting your spirits might also help you take your mind off inhaling that entire bag of Grain Waves, and a study published in the Journal of Experimental Social Psychology backs this. Researchers first depleted people's reserves of willpower by asking them to eat only radishes while leaving them alone in a room filled with biscuits and chocolate. Next, some of the volunteers watched a short comedy video while others viewed an educational film. Then the entire group was asked to perform the same mental task. Guess who did better.

The results show that even small doses of pleasant emotions can quickly renew your ability to say no. So the next time you're facing down seemingly irresistable temptation, dig out your Eagle vs Shark DVD or treat yourself to that fabulous pair of shoes you've been eyeing. Sure, the good feelings you experience might only be temporary, but they will certainly last long enough to get you safely past that doughnut shop.

Quick tips to help bolster your resolve

• Sleep for 7+ hours Research shows that getting less than six hours of shut-eye a night reduces your decision-making ability, leading to what psychologist Dr Kathleen Vohs calls "failures of self-control".
  At a pinch Squeeze the bud of cartilage at the start of your ear canal. This is the acupressure point that's supposed to short-circuit cravings. Can't hurt, and better than squeezing a Picnic bar into your gob, at any rate.
  Don't get cocky A US study of smokers who quit found that the higher people rated their willpower, the more likely they were to cave in to temptation