There are many widely-believed health and fitness myths that simply aren’t true.

For example, it’s commonly believed that weights will make you bulk up and carbs will make you fat, neither of which are true.

And one of the most prevalent myths has now been debunked by a personal trainer - apparently sit-ups won’t give you a flat stomach or washboard abs after all.

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Celebrity personal trainer Nicola Addison, whose clients include Elle MacPherson and Daisy Lowe, has explained that what you need to do is planks and weights whilst eating a healthy diet. Sounds pretty appealing, right?

The trouble with sit-ups and crunches is that although they may help you tone the muscle on your abdominals, they won’t help you shift the layer of fat round your middle so your muscles will stay hidden.

“Sit-ups unfortunately do not reduce fat from the tummy - as much as you might want to believe it, spot reduction of fat is a myth,” Addison explained to the Mail Online.

Of course, no one needs a flat stomach or a six-pack, but if that’s what you’re after, her advice could help you get there quicker.

Here’s what to do:

The first step is building muscle. “Learn to love weights,” Addison says.

The more muscle you have, the more calories you burn, not only when you’re working out but all the time thanks to your boosted base metabolic rate.

Studies have found that frequent weight training can raise your basal metabolic rate by 15 per cent.

The exercise it takes to burn off high-calorie foods Show all 10 1 /10 The exercise it takes to burn off high-calorie foods The exercise it takes to burn off high-calorie foods Sugary soft drink - 330ml - 138 calories Walk off: 26 minutes. Run off: 13 minutes. JOEL SAGET/AFP/Getty Images The exercise it takes to burn off high-calorie foods Standard chocolate bar - 229 calories Walk off: 42 minutes. Run off: 22 minutes. Koichi Kamoshida/Getty Images The exercise it takes to burn off high-calorie foods Chicken and bacon sandwich - 445 calories Walk off: 1 hour 22 minutes. Run off: 42 minutes. Justin Sullivan/Getty Images The exercise it takes to burn off high-calorie foods One quarter of a large pizza (449kcal) Walk off: 1 hour 23 minutes. Run off: 43 minutes. Getty Images The exercise it takes to burn off high-calorie foods Medium mocha coffee - 290kcal calories Walk off: 53 minutes. Run off: 28 minutes. Getty Images The exercise it takes to burn off high-calorie foods Packet of crisps - 171 calories Walk off: 31 minutes. Run off: 16 minutes. Evan-Amos/Creative Commons The exercise it takes to burn off high-calorie foods Dry roasted peanuts - 50g - 296kcal Walk off: 54 minutes. Run off: 28 minutes. Getty Images The exercise it takes to burn off high-calorie foods Iced cinnamon roll - 420 calories Walk off: 31 minutes. Run off: 16 minutes. Justin Sullivan/Getty Images The exercise it takes to burn off high-calorie foods One bowl of cereal - 172 calories Walk off: 31 minutes. Run off: 16 minutes. Getty Images The exercise it takes to burn off high-calorie foods Blueberry muffin - 265 calories Walk off: 48 minutes. Run off: 25 minutes. Isabelle Hurbain-Palatin/Creative Commons

Next, you need to start doing “compound workouts” - exercises that use various muscle groups and joints at once.

Once you’ve mastered that, incorporate planks into your regime.

Regular planking will help you build a strong core, strengthen the abdominal wall, protect the back and compress the abdomen.

And finally there’s the disappointing truth that abs are made in the kitchen, and you’ll never be able to out-train a bad diet.

Cut down on processed foods, sugar, salt, saturated and trans fats so as not to undo all your hard work in the gym.

According to Addison, by including more protein in your diet and working on the moves above, “you should start seeing some stomach definition in no time.”