I suggest you start by doing one set of 10 repeats of each of these in Week 1 of the diet (with 20-second holds on the planks). In other words: 10 press-ups, 10 crunches, 10 squats. Do this three times in the first week. Aim for two sets of 10 repeats by Week 2, and three sets by Week 4.

The Fast 800 has three stages: Rapid Weight Loss, the New 5:2 and Maintenance. I am not going to be prescriptive about how long you stay in the first two stages because that depends entirely on how much weight you want to lose and whether you are finding that particular stage easy to stick to.

on a slice of rye bread (add 55 cals) or wholemeal sourdough toast (add 72 cals).

This means eating generous amounts of foods such as oily fish, seafood, chicken, some red meat, eggs, tofu, beans, pulses, dairy and nuts. If you are a vegetarian or vegan there are alternatives (see page 101). You need at least 50-60g of protein a day, every day. As you get older, you need more.

Red Lentil and Coconut Soup 280 cals Serves 4 A tasty, aromatic soup packed with fibre and protein. 3 tsp coriander seeds, lightly crushed 2 tsp cumin seeds 1 tbsp olive oil 2 leeks, trimmed and thinly sliced 3 garlic cloves, crushed 140g red lentils 400ml tin light coconut milk juice of ½ lime 600ml vegetable stock 2 tbsp flaked almonds, toasted

But the thing that really sets them apart is that they are a mixture of fats and carbs. And not any old mixture. Broadly speaking, whether it is chocolate or crisps, cake or cheeseburger, they are all made up of roughly 1g fat to 2g carbs. It is a ratio that we seem to find particularly irresistible. The 2:1 ratio Milk chocolate, per 100g – 30g fat

Lemon and Thyme Chicken Kebabs 220 cals Serves 2 Not only do chicken thighs contain more nutrients than breast meat, they are also more succulent and flavourful. Kebabs are well designed for eating on the hoof – take them to work in a lunchbox with a generous salad and a dressing in a small jar. 4 small, boneless, skinless chicken thighs, diced (ab

So when she came across Valter’s research showing that short-term fasting could reprogramme a faulty immune system, she decided she would give it a go.

As well as cutting down to 800 calories a day, I recommend adding in a Time Restricted Eating (TRE) programme. This means, from the start, aiming for a 12-hour overnight fast. More on how to do this on page 139.