Obesity is a serious condition especially prevalent in the west. Now scientists at Harvard University have found something that may help in improving westerners' diets: upping daily intake of fruit actually prevents weight gain, even when eating the same amount of calories.
Researchers say it is all to do with flavonoids, naturally occurring compounds which occur in fruits and vegetables and have been linked to weight loss.
"Our results suggest that choosing high flavonoid fruits and vegetables,such as apples, pears, berries, and peppers, may help with weight control," said Monica Bertoia, Harvard T H Chan School of Public Health
To test which flavonoids were most effective, they followed nearly 125,000 people between 27 and 65 over 25 years monitoring their diet, lifestyle habits and weight.
Figures showed that increasing levels of anthocyanins, flavonoid polymers and flavonols - which are found mainly in blueberries, strawberries, apples, pears and oranges - had the greatest overall impact. Onions were also beneficial.
Each extra portion a day brought weight down by a quarter of a lb over four years (100 grams), so sticking to a five-a-day regime could bring weight loss of 1.2lbs (or half a kilogram) over the same time period.
The authors say that people struggling to hit their five-a-day target could help themselves by choosing those with high levels of flavonoids. While the study was observational, the authors expressed hope that people might eat more fruit if they knew a favorite berry helps with weight loss. Most Americans eat less than a cup of fruit and less than two cups of vegetables a day, research has shown.
As for the UK, Tracy Parker, dietitian at the British Heart Foundation, said: "Although the mechanisms of the benefit of eating fruit and vegetables are not well understood, this study suggests that eating fruit and vegetables that contain high levels of flavonoids could help people maintain a healthy weight.''
Recently the UK government has been called on to cut the price of fruit and veg, in light of the studies' findings.
Tam Fry of the National Obesity Forum said: “Cheap junk food has made buying any fruit seem expensive and until the overall cost of going to the greengrocers is addressed, one key to tackling obesity will have been lost.”
He added: “It is imperative that David Cameron’s anticipated strategy to defeat obesity focuses on ways to make the healthier choice cheaper.”
Sources: telegraph.co.uk, edition.cnn.com, express.co.uk