A 2016 study found that flavonoids in certain fruits and in tea may help prevent weight gain in adults. The study, published in the BMJ, looked at data from 124,086 adults participating in the Health Professionals Follow Up Study, the Nurses’ Health Study, and the Nurses’ Health Study II. Every two years for 20 to 24 years, participants answered questions regarding their weight, lifestyle, and changes in health status. Every four years during the same period of time, participants also answered questions regarding their diet, which researchers analyzed for seven types of flavonoids, including anthocyanins, flavonoid polymers, and flavonols. After adjusting for smoking and exercise habits, as well as for dietary and lifestyle factors, researchers found that:
Each standard deviation (a statistical unit) increase in consumption of anthocyanins, mainly from blueberries and strawberries, was associated with a 0.23 pound reduction in weight gained over a four-year period.
Each standard deviation increase in consumption of flavonoid polymers, mainly from tea and apples, was associated with a 0.18 pound reduction in weight gained over a four-year period.
Each standard deviation increase in consumption of flavonols, mainly from citrus fruits and juices, was associated with a 0.16 pound reduction in weight gained over a four-year period.
Like most studies correlating eating habits to health, these associations are based solely on observation. Controlled trials are needed to show a direct link between flavonoids from fruits and weight maintenance. Nevertheless, numerous studies have suggested that eating fruit, which is naturally low in calories and high in nutrients and fiber, can help reduce risks of certain chronic diseases like heart disease and diabetes. So, if your goal is to stay healthy while (possibly) keeping the pounds off, it wouldn't be a bad idea to make room for fruit in your daily diet.