"I think the media talk a load of crap about diets," he declares, "and doctors don't know a lot about nutrition."

In a market saturated with so-called superfoods and fad diet, Haskell aims to cut through the noise with a refreshingly straightforward message: Healthy eating is simple, and yes, of course everyone can do it.

"Every time you go online and ask about diet, suddenly there's 17 different ways to skin a cat. It's just not the case. You just have to understand a few rules - calories in, calories out, and to look at your plate as a pie chart," he says.

Alongside sleep and hydration, it is this 'pie chart' that sustains Haskell's punishing gym routine, and his famously big hits on the rugby field. So what does a pie chart contain?

First, there's the protein, second is an energy source ("If you do a lot of training, you need a lot of carbohydrates"). And thirdly, "decent fats and vegetables". Three meals, three basic food groups: In the gospel of Haskell, it needn't be much more complicated than that.

Even if you question Haskell's credentials as a nutrition expert, there's no doubting the know-how of his collaborator, sporting chef-to-the-stars, Omar Meziane.

Meziane knows a thing or two because he's seen a thing or two. After working with Haskell at Wasps, he catered for the British Rowing Team, and then spent the summer in Russia cooking for Gareth Southgate's England squad. "He understood how to fuel us but in a really tasty way," says Haskell. "He kept things very simple. You don't have to see a witch doctor to get any of the foods."

BACON, JALAPENO AND BUTTER BEAN OMELETTE

Ingredients:

(serves 1)

2 slices of streaky bacon

4 slices of pickled jalapeno chilli, or 1/2 a fresh green chilli, freshly chopped

3 large eggs

1 knob of butter

50g cooked butter beans

Salt and pepper

Method:

1. Preheat the grill to high. Place the bacon on a tray and cook under the grill for seven to eight minutes, or until cooked through. Allow it to cool before slicing into strips, half a centimetre thick, and set aside. Stir in the jalapeno chilli.

2. Crack the eggs into a bowl and season with salt and pepper. Whisk the eggs well. Heat a frying pan over a medium heat and add the butter. Pour the eggs into the pan and cook the omelette for two minutes or until it has started to set on the bottom. Now sprinkle the bacon and jalapeno over the omelette and top with the butter beans. Pop under the grill for 30 seconds. Turn out onto a plate and serve immediately.

SWEET POTATO, CHICKPEA AND KALE SOUP

Ingredients:

(serves 2)

1tbsp of olive oil

1 garlic clove, finely sliced

1 large sweet potato, peeled and cut into 2cm dice

400g tinned chickpeas, drained

1.5L hot water

1 vegetable stock cube

1 pinch ground cinnamon

1 pinch ground cumin

4 large kale leaves, chopped

Method:

1. Preheat your oven to 200°C. Heat the olive oil in a large saucepan over a high heat. Place the garlic and half of the sweet potato in the pan and cook for two to three minutes without colouring. Add half of the chickpeas and continue to cook for one minute.

2. Boil the kettle and pour the one-and-a-half litres of hot water into a jug, then dissolve the stock cube in the water. Pour the stock into the pan of sweet potato and add the cinnamon and cumin. Bring the soup to the boil and then turn down to a gentle simmer. Cook for 25 minutes, or until the sweet potato is cooked through. Allow the soup to cool a little before placing it into a food processor and blending until smooth. Adjust the seasoning, and pour back into the saucepan.

3. While the soup is cooking, place the remaining potato chunks on a baking tray, and bake in the oven for 15-20 minutes or until cooked through.

4. Place the saucepan of soup over a low-medium heat and add the remaining chickpeas and the kale. Now add the baked sweet potato chunks into the soup. Serve as soon as the soup is nice and hot.

SEA BASS WITH GINGER AND TAMARI

Ingredients:

(serves 2)

180g brown rice

80g edamame beans

1/2 small bunch coriander, finely chopped

2 whole sea bass

2 garlic cloves, finely chopped

1cm piece of ginger, finely chopped

1 red chilli, finely chopped

3tbsp tamari or soy sauce

4 spring onions, finely chopped

Method:

1. Preheat your grill to high.

2. Place the rice in a saucepan and cover it with water. Bring the pan to boil and cook for 10 minutes, or according to the pack instructions. Drain away any excess water, put the rice back into the saucepan and then set it aside. Now bring a small saucepan of water to the boil and carefully add the edamame beans. Boil the beans for five minutes before draining and mixing together them with the rice. Stir in the finely chopped coriander.

3. Place the sea bass on a roasting tray skin-side up. Sprinkle the garlic, ginger and chilli over the fish. Spoon over the tamari and place the tray under the hot grill. Cook for 15 minutes. Baste the fish with the sauce in the roasting tray.

4. Divide the rice between two plates and then top with the fish. Spoon over any excess sauce, scatter the spring onions over the fish, and serve.

Cooking For Fitness by James Haskell & Omar Meziane is published by Haskell Publishing. Available now.