A new study from researchers at the University of Alabama at Birmingham claims that a common weight-loss tactic of increasing the feeling of being full by eating more fruits and vegetables is not an effective diet recommendation.
The University of Alabama at Birmingham (UAB) team performed a systematic review and meta-analysis of the available data on increasing fruit and vegetable intake as a weight-loss aid. The review - which is published in the American Journal of Clinical Nutrition - looked at several randomized controlled trials involving more than 1,200 participants in total.
According to the UAB researchers, there is no evidence that increasing fruit and vegetable intake reduces body weight.
"Across the board, all studies we reviewed showed a near-zero effect on weight loss," says lead author Kathryn Kaiser, PhD, instructor in the UAB School of Public Health.
"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."
Dr. Kaiser says that in the context of a healthy diet, the best way to reduce weight is to reduce caloric intake. Although dieters might make the assumption that high-fiber fruits and vegetables "displace" the less healthy foods, this is not demonstrated in the available evidence.
Researchers suggest public health communications should be amended
Senior author David B. Allison, PhD, associate dean for science in the UAB School of Public Health, explains the problem with communicating to the public why this technique is ineffective:
"In public health, we want to send positive and encouraging messages and telling people to eat more fruits and vegetables seems far more positive and encouraging than just saying 'eat less.' Unfortunately, it seems that if we just get people to eat more fruits and vegetables without also taking explicit steps to reduce total food intake, lower weights are not achieved."
As public health recommendations are focused on increasing fruit and vegetable consumption, Dr. Kaiser believes public health messages should be modified to explain that there are many health benefits associated with eating fruit and vegetables, but that weight loss is not one of them.
All of the studies in UAB's systematic review showed that adding more fruits and vegetables to a diet without reducing total food intake had "a near-zero effect on weight loss."
"I think working on more multimodal healthy lifestyle interventions would be a better use of time and money," she suggests.
Dr. Kaiser adds that it is important that more quality research investigates the interactions of multiple foods in creating healthy weight loss that can be maintained.
"We need to design mechanistic studies to understand these things better so we can help the public be best informed and know what to do when it comes to weight-loss efforts," she concludes. "Overly simplified messages don't seem to be very effective."
However, recent research has shown that the benefits of a diet with higher fruit and vegetable intake include lower risk of dying from ischemic heart disease, reduced stroke and pancreatitis risk, and even a more attractive "glow."
While the UAB systematic review may not prove that simply adding extra fruit and vegetables to your diet will result in weight loss, the importance of fruit and vegetables in a healthy diet should still not be underestimated.