Researchers from the University of Alabama at Birmingham have discovered that having more fruits and vegetables in a person's diet will have no effect on weight loss, which is contrary to the often recommended notion of eating more of them to lose weight.
The research team utilized data of over 1,200 test subjects in seven controlled and randomized experiments that explores the effects on weight loss when people begin to eat more fruits and vegetables in their daily diet.
"Across the board, all studies we reviewed showed a near-zero effect on weight loss," said Kathryn Kaiser, Ph.D., UAB School of Public Health instructor and the leader of the research team.
"So I don't think eating more alone is necessarily an effective approach for weight loss because just adding them on top of whatever foods a person may be eating is not likely to cause weight change."
The study, which was published in the American Journal of Clinical Nutrition on June 25, also found out that while eating more fruits and vegetables will not help a person lose more weight, it will also not make the person gain weight.
Kaiser said that increasing the serving size of fruit does not increase a person's weight, which makes eating fruit a very effective way of acquiring the body's daily requirements of vitamins and fiber.
Kaiser adds that to lose weight while keeping a healthy diet, the best way is to reduce total caloric intake, not just increase the intake of fruits and vegetables, as according to popular belief.
The MyPlate Initiative of the United States Department of Agriculture recommends a daily serving requirement of one and a half to two cups of fruit and two to three cups of vegetables for adults. People looking to shave off a few pounds in their weight are often recommended to include more in their daily diet, as it is assumed that the low-calorie fruits and vegetables will take up space in a person's digestive tract, satisfying hunger without consuming fat.
"People make the assumption that higher-fiber foods like fruits and vegetables will displace the less healthy foods, and that's a mechanism to lose weight," Kaiser said.
However, the study's findings show that the desired weight loss effect is not achieved for people who only increase their consumption of fruits and vegetables -- they also have to cut total calorie intake.
The research continues the trend of reports disproving long-standing dietary beliefs. A study published in 2008 in the International Journal of Obesity revealed that having two eggs for breakfast will contribute to weight loss on an energy-deficit diet of 1,000 calories a day, which is surprising because eggs are often viewed as food that causes weight gain.
Researchers note in the abstract of that study that the egg breakfast enhances weight loss, when combined with an energy-deficit diet, but does not induce weight loss in a free-living condition. They concluded adding eggs in a weight management program may offer a nutritious supplement to enhance weight loss.