The richness of the human experience is that cultures and traditions are very specific to a time and place. While exploring how other people live is soul-enriching, it can also serve a scientific objective. Researchers have studied specific populations around the world to understand why some people are healthier than others.
The question of longevity is far from settled but research suggests calorie restriction may be a key contributor.
As Dr Sarah Brewer, Medical Director at Healthspan explained to Express.co.uk, animal studies suggest prolonged calorie restriction can extend lifespan but how far these findings can be extrapolated to humans is unknown.
“The strongest evidence comes from inhabitants of Okinawa island in Japan, where there are five times more centenarians compared with other industrialised countries,” she said.
“In Japan, longevity is sought through a philosophy of dietary restriction known as ‘hara hachi bu’ which translates as ‘eight parts out of 10’ – in other words, practitioners aim to eat only until they are 80 percent full.”
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According to Dr Brewer, scientists have recognised for over 80 years that restricting your calorie intake can improve health and has the potential to extend life – as long as you avoid vitamin and mineral deficiencies.
As she explained, the 80 percent full rule appears to be sufficient to activate SIRT1 production – a protein which promotes the long-term survival of irreplaceable cells by increasing free radical protection.
“If the gene that codes for SIRT1 is switched off or deleted then calorie restriction does not extend lifespans.”
Conversely, as Dr Brewer explained, if the SIRT1 gene is switched on then lifespan is extended.
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Research continues to elucidate the benefits of calorie restriction.
One study published in the Cell Metabolism journal this month concluded that cutting calorie intake by 15 percent over two years can slow ageing and protect against diseases such as cancer, diabetes, and Alzheimer’s.
A different, more extreme calorie-restricted diet study published in Science Translational Medicine showed that so-called “fasting-mimicking” diets practiced for five days a month for three months can also help the body with ageing.
There are some important considerations, however.
According to the NHS, very low calorie diets should only be followed under medical supervision for a maximum of 12 weeks.
“Do not follow a very low calorie diet unless a GP has suggested it to you,” warns the health body.
Also, very low calorie diets are less likely to be nutritionally complete as they provide far fewer calories than needed to maintain a healthy weight, it notes.
Very low calorie diets are not suitable if you are:
- Under 18
- Have had an eating disorder.
As well as looking at how much you’re eating, it also helps to think about other behaviours and habits you may have formed around food.
“You might already know which foods are healthy and unhealthy – but in practice it can be hard to break old habits,” says Bupa.
One handy tip is to try to stick to regular, planned meal times.
“If you feel hungry between meals, try having a glass of water and waiting 20 minutes to see if you still feel hungry,” advises Bupa.