Counter-intuitive as it may seem, no foods are off-limits, none proscribed. On the five days a week when we’re not restricting calories, we both eat freely – fish and chips, roast potatoes, biscuits, cake. The Illinois study certainly found that volunteers encouraged to eat lasagne, pizza and fries during ‘off days’ still lost weight.

Male or female, your waist should be less than half your height.

In a study from 2005, eight healthy young men were asked to fast every other day, 20 hours a day, for two weeks.12 On their fasting days they were allowed to eat until 10pm, then not eat again until 6pm the following evening. They were also asked to eat heartily the rest of the time to make sure they did not lose any weight.

I assumed that when you get hungry it builds and builds until it becomes intolerable, and so you bury your face in a vat of ice cream. I found instead that hunger passes and once you have been really hungry you no longer fear

felt a certain trepidation as I realised that for the next four days I would be drinking nothing but water, sugarless black tea and coffee, and one measly cup of low-calorie soup a day.

Varady, KA; Surabhi Bhutani; Church EC; Kempel, M. ‘Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardio-protection in obese adults.’. American Journal of Clinical Nutrition, November 2009 & Klempel MC, Kroeger CM, Varady KA. ‘Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and

Insulin-Like Growth Factor 1. IGF-1, as its name implies, has growth-promoting effects on almost every cell in your body. It keeps your cells constantly active. You need adequate levels of IGF-1 and other growth factors when you are young and growing, but high levels later in life appear to lead to accelerated ageing and cancer. As Valter put it,

Valter recommends that you don’t eat more than 0.8g of protein per kg of body weight per day. For someone like me, that would be around 64g a day.

Try the two-to-two: fasting not from bedtime to bedtime, but from 2pm until 2pm. After lunch on day one, eat sparingly until a late lunch the following day. That way, you lose weight as you sleep and no single day feels uncomfortably deprived of food. It’s a clever trick, but it does require a modicum more concentration than the whole-day option.