Nutrition and fitness expert Joe Wicks, 30, has gone, in just two years, from someone trying to help people by posting advice on Instagram (which, he says, ‘about two people watched’) to being something of a phenomenon. His two books – Lean in 15 and Lean in 15: The Shape Plan – have both been bestsellers, he has a Channel 4 show provisionally called Joe Wicks: Body Coach, to be broadcast soon and more than 100,000 graduates report remarkable results from his 90-Day Nutrition and Fitness Plan. But if you’re negative, forget it. ‘I can’t bear a Moaning Minnie or a Negative Norman,’ he says. ‘I have clients with diabetes, polycystic ovary syndrome, thyroid and other conditions who have had amazing results. There are 20-year-olds on my plan, and 70-year-olds. The fact is, if you want to be lean, you can be – and I can totally help you.’

SO WHERE DO WE START

‘It’s all about prepping like a boss,’ he says. ‘We all lead busy lives and if you’re reading this on the Tube, you might have grabbed a high-sugar cereal bar, a coffee, a banana. The key is, if you prep the night before and know what you are eating the next day, you will eat better.

‘If you want to wake up and do a quick 20-minute HIIT (High Intensity Interval Training) exercise session, you can then wolf down some overnight oats, or stick them in a tub and take them to work, knowing you are fuelling yourself and will be burning fat for the rest of the day.

‘If you’ve got a salad or left over stir-fry, that will sort you out for lunch. Then go home and make a nice fresh dinner. The most successful “leanies” are those who prep like a boss.’

Although eating the right food is clearly important, so is exercise. Joe chooses to do his workout first thing in the morning and, he says, afterwards, you need to refuel with carbs – and not tiny amounts either. ‘You can have big portions,’ he says, ‘it just has to be the right kind of food.’

He says: ‘Remember this isn’t a diet. It’s about changing how you eat and exercise. If you slump after lunch, it’s likely to be because you are not giving your body the fuel it needs.’

It’s hard not to be carried along by Joe’s enthusiasm as many are (he’s now got not two but 1.2 million followers on Instagram).

‘My whole ethos,’ he says, ‘is about being encouraging and positive. There are many things I want to achieve and, until I’ve got the world off diets, I’m not going to stop.’

To find out more, go to TheBodyCoach.co.uk. You can also try these recipes.

Lean in 15: The Shape Plan by Joe Wicks (£16.99, Bluebird) is out now.

FUEL YOURSELF PROPERLY

1. Eat a big nourishing lunch – forget that pasty or stodgy sandwich.

2. Always drink water before you exercise. You’ll be amazed how great you’ll feel if you drink two litres of water a day.

3. Get some fresh air. Sitting at a desk all day would make even an insomniac tired.

4. If you must snack – and by eating the right foods at the right time you shouldn’t need to – have a handful of nuts, a boiled egg or a piece of fruit.

Read more: London’s healthiest lunch boxes 

PEAR AND CRANBERRY OVERNIGHT OATS

Serves 1

* 75g frozen cranberries, plus, if you wish, a few extra to serve
* 1 pear, cored and chopped into rough pieces – skin and all
* 175ml almond milk
* 1tbsp Greek yogurt
* 1tbsp honey
* 1 scoop (30g) vanilla protein powder
* 100g rolled oats
* Flaxseeds, to serve
* Chopped toasted hazelnuts, to serve

Chuck the cranberries, pear, almond milk, Greek yogurt, honey and protein powder into a small blender and blitz until smooth.

Pour the mixture over the oats and leave to soak in an airtight container in the fridge for a minimum of 6 hours, but preferably overnight.

Just before eating, scatter with the flaxseeds, toasted hazelnuts and a few extra cranberries, if using, to serve. I’ve chosen Hazelnuts and Flaxeeds, but go with whatever seeds you have.

MONKFISH KEBABS WITH TABBOULEH

Serves 1

* 50g dried bulgur wheat
* 250g monkfish, trimmed and chopped into 2–3cm chunks
* Drizzle of olive oil
* Salt and pepper
* 3tbsp chopped parsley
* 2tbsp chopped mint
* 2tbsp chopped coriander
* 1 ripe tomato, roughly chopped
* 2 roasted red peppers from a jar, roughly sliced
* 2 spring onions, finely sliced
* 2 lemons
* Pitta bread, to serve

Preheat your grill to maximum and bring a saucepan of water to the boil. As soon as the water has boiled, dump in the bulgur wheat and cook according to the packet instructions (about 8 minutes) before draining through a fine sieve and rinsing under cold water.

Slide the monkfish onto one massive skewer or two smaller ones. Drizzle with olive oil and season with salt and pepper. Grill the monkfish for 8 to 9 minutes, rotating a couple of times
while cooking.

Tip the drained bulgur wheat into a bowl and add the chopped herbs, the tomato (scraping in all the tomato juice too), red pepper, spring onions, the juice of 1 lemon and a generous pinch of salt and pepper. Mix together.

Serve up the tabbouleh with the cooked monkfish skewers on top, a final spritz of lemon juice, some grated lemon zest and pitta bread on the side.

NAUGHTY STEAK BURRITO WITH PINEAPPLE SALSA

Serves 1 (makes 2 wraps)

* ½tbsp coconut oil
* 1 x 225g sirloin steak, sliced into 1cm thick strips
* 5 spring onions, finely sliced
* 2tsp jerk seasoning
* 100g pre-cooked rice
* 40g tinned kidney beans, drained and rinsed
* 2tbsp chopped coriander
* 75g pineapple, chopped into 1cm pieces
* 1 red chilli, finely sliced (remove the seeds if you don’t like it hot)
* 1 lime
* Salt and pepper
* 2 large tortilla wraps
* Shredded iceberg lettuce, to serve

Melt the coconut oil in a wok or large frying pan over a high heat. Add the steak strips and stir-fry for 1–2 minutes until they’re nice and brown, but still a little rare. Chuck in the spring onions and jerk seasoning and continue to stir-fry for 1 minute.

Next, add the rice and kidney beans, crumbling the rice between your fingers as you drop it in. Pour in about 2tbsp of water, which will help warm through the rice and beans.

Stir the ingredients for about 2 minutes until the rice is warmed through. Remove the pan from the heat and stir through 1tbsp of chopped coriander. Keep to one side while you make the salsa.

Place the remaining coriander, pineapple chunks, chilli and the juice of half the lime in a bowl along with a small pinch of salt and pepper. Mix the ingredients together until well combined.

Zap the tortillas in the microwave at 900w for 20 seconds. Construct your wraps by piling up the rice and steak, topping with the lettuce and salsa, and then finishing with a squeeze of lime juice.