Pinned to my mother Shirley’s fridge on yellowing, curled paper is a handwritten copy of a two-week crash diet. It has been there since 1979, the year she decided she wanted to shed a stone in a fortnight. Its survival is testament to the faith she holds in it.
Among other tortures while on the diet, she allows herself no more than half a grapefruit and a slice of dry toast with black coffee each morning. Lunch is a few cold cuts of meat and a side of vegetables, and dinner is similar. On a typical day this will amount to about 650 calories.
Now 78, you would have thought she’d have deserted this gruelling regime and allowed herself to go into diet retirement.
But like so many women of her generation, she believes the occasional fortnight of eating little is key to a svelte figure and good health.
Such extreme slimming plans have drifted out of fashion in the past few decades. Crash diets are supposed to slow your metabolism down, leading to more weight gain when you stop.
These days, the mantra recited by the medical profession is steady weight loss rather than starvation. And being curvy – a la Mad Men’s Christina Hendricks – is in vogue.
But it may be time to reconsider this approach. And my mother, with her maddening crash diet, might be on to something. Tomorrow, a BBC TV Horizon investigation looks into the health benefits of fasting.
Science reporter Michael Mosley speaks to scientists who have discovered that periods of eating very little or nothing may be the key to controlling chemicals produced by the body linked to the development of disease and the ageing process. This backs up recent studies on animals fed very low-calorie diets which found the thinnest (without being medically underweight or malnourished) are the healthiest and live the longest.
The key, say researchers at the University of Southern California’s Longevity Institute, is the hormone Insulin-Like Growth Factor 1 (IGF-1). Mosley explains: ‘IGF-1 and other growth factors keep our cells constantly active. It’s like driving with your foot on the accelerator pedal, which is fine when your body is shiny and new, but keep doing this all the time and it will break down.’
According to Professor Valter Longo, director of the Longevity Institute, one way to take the foot off the accelerator, and reduce IGF-1 levels dramatically – as well as cholesterol, and blood pressure – is by fasting.
‘You need adequate levels of IGF-1 and other growth factors when you are growing, but high levels later in life appear to lead to accelerated ageing,’ he says. ‘The evidence comes from animals such as the Laron mice we have bred which have been genetically engineered so they don’t respond to IGF-1. They are small but extraordinarily long-lived.’
The average mouse has a life span of two years – but the Laron typically live 40 per cent longer. The oldest has lived to the human equivalent of 160. They are immune to heart disease and cancer and when they die, as Prof Longo puts it: ‘They simply drop dead.’
During the film, Mosley tries various fasts – for three days straight, and for two days a week, for six weeks – with dramatic results. Not only does he lose weight, but his cholesterol levels and blood pressure improve. These findings chime with recent reports that reaching a ‘healthy’ Body Mass Index (BMI) may not be enough – we need to be as slim as possible to reduce our risk of illness.
The reason experts haven’t emphasised this is that they don’t want to trigger eating disorders or demotivate the overweight trying to get into the healthy weight range. There is only so long, however, we can shy away from this because the evidence keeps mounting.
So has my mother’s generation been right all along? Is striving to be ‘slim as a pin’ good for us? And does this mean those who slip into our size 12 jeans believing we are healthy are fooling ourselves?
Matthew Piper, of the Institute of Healthy Ageing, University College London, says: ‘Studies on monkeys show if we restrict the diet there is a delay in the onset of cancer, coronary heart disease and diabetes in later life as well as staving off dementia.’
Reducing our food intake over months or years could boost lifespan by 15 to 30 per cent, experts believe.
My mother says her determination to stay slender comes from her childhood during the war. ‘We were on rations until 1954, so everyone was slim. Now food is everywhere,’ she says, repeating to me two phrases she learnt from her mother – ‘He who sleeps, eats’ and ‘You have to suffer to be beautiful’.