It is a longstanding principle of nutrition — and basic science — that in order to lose weight, people must consume fewer calories (less energy) than they expend. This principle often leads to the recommendation that people eat less fat, which has more calories per gram than carbohydrate or protein, and more fruits and vegetables, which are often high in fiber and water and relatively low in calories. As last week’s post makes clear, the benefits and risks of limiting dietary fat in people with diabetes (especially Type 2 diabetes) are still being studied and debated. But eating more fruits and vegetables can only be helpful — right?
A new research review, however, finds that consuming fruits and vegetables has little to no effect on weight control — contradicting one of the main reasons they are often recommended both generally and for people with diabetes. Published last week in The American Journal of Clinical Nutrition, the analysis was based on seven studies that met most of the criteria researchers were looking for (measuring weight or fat loss/gain, evaluating a variety of minimally processed fruits and/or vegetables, and involving 15 or more subjects for at least 8 weeks). As noted in an article on the review at HealthDay, the researchers found that among the combined study group of about 1,200 from the seven studies, the average change in body weight — after including more fruits and vegetables in the diet for an extended period — was not statistically significant.
The studies included in this review were chosen because they simply measured how added fruit-and-vegetable consumption affected weight, without any other dietary or lifestyle changes. Some proponents of fruits and vegetables for weight loss maintain that simply adding them to the diet is not enough — instead, they note, overall calories must be reduced, and adding fruits and vegetables can be a good way to maintain the volume of food intake and reduce hunger as part of this process. The Centers for Disease Control and Prevention (CDC) takes this position in a pamphlet entitled “Can eating fruits and vegetables help people to manage their weight?” which cites a number of studies that reach this conclusion. Two research reviews from 2004, published in the journal Nutrition Reviews, also conclude that both clinical and population-based studies support the idea of fruits and vegetables supporting weight control. A 2012 study published in the Journal of Primary Care and Community Health also came to this conclusion, with the most dramatic effects seen at the very highest levels of fruit and vegetable consumption.
Have you found that you eat fewer, or more, calories when you include more fruits and vegetables in your diet? Is it your experience that these foods help support weight loss, or have you not found this to be the case? Are there any downsides to eating more fruits and vegetables? If you’ve successfully lost weight, what role did fruits and vegetables play in achieving or sustaining your weight loss? Leave a comment below!