“The metabolic improvements with a very low-calorie diet, such as a reduction in liver fat and reversal of diabetes, would be expected to improve heart function,” said lead author Dr Jennifer Rayner, of Oxford University. “Instead, heart function got worse in the first week before starting to improve.”
Rayner insisted that patients with heart problems needed to check with their doctors before embarking on a very low calorie diet or fasting, and that their diets should be supervised.
A tendency to ‘yo yo’ diet – as Warne appeared to do – can also be risky. Says Yeo: “If you yo-yo diet in a crazy way – adding and losing stones – that can put an awful lot of stress on your body.” Pigott adds: “Sometimes we have seen big shifts in patients with extreme eating disorders, or who purge and make themselves unwell, which can lead to cardiac arrhythmias and impact kidney function.”
Yeo adds that while being middle-aged, like Warne, is not itself a risk, men are more at risk of heart attacks and other metabolic disorders “because they store fat around their middles – which can lead to cardiovascular problems.”
And what of the “detox diet”? “We do need to detox, but we have kidneys and a liver that detox for us,” says Pigott. “There’s no food you can eat and no diet you can go on that will enhance the detoxification process.”
What can happen to the rest of your body on a crash diet?
By Abigail Buchanan
liver
Extreme dieting can result in your body using lean tissue such as muscle and even liver and heart tissue to make energy, says Dr Duane Mellor, dietician and lead for Nutrition and Evidence Based Medicine at Astor University in Birmingham. “Your liver normally stores glycogen, which is an animal starch that keeps you going between meals and overnight,” he says. “If you don’t have enough energy coming in, your body has to make that glucose [another way]”.
Good
Crash dieting can cause cramping and constipation, says Pigott. “When you have a very low energy intake, your gut has a lot less to process and things slow down. You’re likely to be taking in less fiber and your gut flora and fauna can become a little dysregulated,” she says. “When we return to eating, it can take time for the gut to get used to a normal volume of food again.”
Brain
Crash diets have both physiological and psychological impacts. “Most restrictive diets won’t contain sufficient carbohydrates, so you will need to break down some of your own body fat and protein stores to produce the glucose that your brain needs for energy. That process is slow, so people feel sluggish,” explains Pigott.
