Instagram fitness model reveals the 5 mistakes you've been making with meal prep

Whether you are looking to shift weight, build lean muscle, or just avoid your urge to hit up the local takeaway joint, meal prepping has fast become one of the best ways to ensure you're eating healthily and saving money.

Even if you think you've mastered how to prepare a Tupperware box of food in advance, you might still be making some common mistakes. From making all of the food you plan to eat for the week in one day to not mixing it up enough, fitness star Kayla Itsines recently shared the five meal prepping mistakes you need to avoid.

1. Preparing food that won't fuel your body

For the 26-year-old Kayla, who trains regularly, not making enough food to fuel your body throughout the day is a trap that many would-be meal preppers fall into. But even if your days and workouts aren't quite as gruelling, you still need to make sure you're getting adequate nutrients and something nice. "Include foods that have the right combination of protein, healthy fats and complex carbohydrates. If you don’t, you might feel hungry again soon after a meal, or you might disregard it altogether because it doesn’t seem appetising enough," she said.

2. Preparing the wrong portion sizes

It's all very well and good assuming that meal prepping is healthy, and packing your lunch to take to work will automatically see you shed kilos. But if you're giving yourself either too much or too little food at midday, you could, in fact, end up gaining weight.

Kayla recommends you start by preparing "adequate portion sizes and see how they make you feel", slowly tailoring your food to what is the right amount for you. She also said it's a good idea to look at your portion-sized containers for inspiration as to how much is generally too much or too little.

3. Don't over-complicate things 

Kayla said that meal prep is supposed to make life easier for you, rather than harder. "You don't want to dread preparing meals because you are spending hours making a variety of complicated dishes," she wrote.

Instead, focus on simple but tasty recipes, like stuffed capsicums, chicken with rice and green vegetables and baked potatoes with toppings. The 26-year-old is also a fan of prepping nourishing bowls, stuffed with greens, chickpeas, chicken and avocado.

4. Don't eat the same thing every day

One of the most common things that stops people from meal prepping is that they assume that if you eat the same thing every day, you'll get bored and stop eating it. But Kayla said you shouldn't eat the same thing too much.

"Sure, repeat the same meal a few times, but generally, the more you switch between different meals, the more enjoyable the experience," she said. She added that even if you're sticking to the same ingredients, mix and match the combinations - and change up your vegetables.

5. You've gotta stop making all your food in one day

While you might think that a successful meal prep week all starts with a Sunday of batch cooking, Kayla, in fact, said it's a better idea to have two dedicated days for meal prep. "Breaking up your meal prep time over two different days is an effective way to ensure your food remains as fresh as possible," she explained.

Try a Sunday and a Wednesday for getting everything sorted and cooked. Then, eat the meals that are likely to go off fastest first.

If you make sure everything is delicious and follow Kayla's rules, exercise regularly and even allow yourself a treat or two, you could see yourselves looking at tight as the influencer herself.