The Mediterranean diet is hailed by doctors and scientists for its menu of fruit, vegetables and wholegrains that has been shown to boost heart health.
But now, scientists say a slightly tweaked version — packed with green tea, walnuts and a green smoothie — improved the brain health of obese people who followed it.
Weighing too much has been linked with the brain ageing faster than would normally be expected.
Israeli researchers, who recruited more than 100 obese people to follow the diet, found that for every one per cent drop in their body mass index (BMI), their ‘brain age’ reduced by nine months.
The findings show that it is vital for brain health to maintain a healthy weight and eat less processed foods, sweets and drinks, the researchers said.
But now, scientists say a slightly tweaked version — packed with green vegetables and green tea — improved the brain health of obese people who followed it
The Mediterranean diet — high in healthy fats and proteins but low in carbohydrates — has become extremely popular in recent years with a wealth of studies touting its benefits for longevity, reducing frailty and warding off cancer.
The diet involves largely shunning dairy, red meat and alcohol, while tucking into fruit, vegetables, wholegrains, olive oil, oily fish, nuts, seeds and pulses.
A swathe of evidence has shown that it can aide with weight loss.
Being obese has been linked with having an older looking brain, including a shrinkage in white matter, which helps communication between different regions of the brain.
Researchers at the Ben-Gurion University of the Negev recruited 102 obese volunteers, who were mostly men and aged 52, on average.
They were asked to follow a ‘green’ Mediterranean diet for 18 months, which involved consume 28g of walnuts daily, three to four cups of green tea and a 100g green shake made with globosa — a type of plant supplement.
They were also told to cut out red meat and sweets.
Women were asked to consume no more than 1,200 to 1,400 calories a day, while men stuck to between 1,500 and 1,800 calories per day.
MRI brain scans were completed at the start and end of the trial to calculate ‘brain age’ — hold old the brain appears on scans, regardless of biological age.
During the study, all participants received a free gym membership and educational sessions encouraging moderate-intensity physical activity.
They were also asked to attend 45 to 60 minute sessions of aerobic and resistance training three or four times per week.
Measurements were also taken of participants body weight and waist circumference.
Writing in the journal eLife, researchers said 56.8 per cent of those following the green Mediterranean diet had a lower brain age than expected at the end of the study.
And they spotted that every one per cent drop in BMI or weight correlated to a nine-month drop in brain age.
Those in this group saw their BMI reduce by 0.76 units, lost 5lbs (2.31kg) and 5.39cm from their waist, on average.
Study author Dr Gidon Levakov, of the university’s Department of Brain and Cognitive Sciences, said: ‘Our study highlights the importance of a healthy lifestyle, including lower consumption of processed food, sweets, and beverages, in maintaining brain health.
Co-author Professor Galia Avidan said: ‘We were encouraged to find that even a weight loss of 1 per cent was sufficient to affect brain health and lead to a 9-month reduction in brain age.’
However, the scientists did not study whether the drop in brain age affected the participants cognition. They noted that the findings are also limited by most participants being men and a lack of control group to compare the findings to.
One million patients, who were a healthy weight with a body mass index (BMI) of 18 to 25, were calculated to cost the NHS an average of £638 each in 2019, the final year of the study. By comparison, severely obese patients with a BMI of 40 and above cost more than double – at £1,375 annually. Meanwhile, the NHS spent £979 a year on obese patients with a BMI of 30 to 35, which increased to £1,178 a year for those with a BMI of 35-40
Studies have previously suggested weight loss, lowering blood pressure and controlling blood sugar levels reduced the loss of brain cells.
Research has also linked obesity with decreasing connectivity within the default mode network – the part of the brain active during passive rest.
Obesity is also associated with multiple adverse health impacts.
Latest NHS data shows 26 per cent of adults in England are obese and a further 38 per cent are overweight but not obese. One third of Americans are overweight, while four in 10 are obese.
Obesity rates have been on the rise for decades, with experts blaming sedentary lifestyles and unhealthy diets.
They are also soaring in children, with a quarter of children in reception in England now considered overweight, and one in ten obese.
A landmark study earlier this month also revealed UK’s bulging waistline is stripping billions of pounds from the cash-strapped NHS each year, with twice as much spent on obese patients, as on those of a healthy weight.
Costs per patient rise drastically the more people weigh, as they ‘collect obesity-related conditions’ such as type 2 diabetes, cancer and heart disease, according to research involving nearly 2.5million people.
