I’m very skeptical of promises that sound too good to be true.
No field is as rife with these as the diet industry, where new dream diets are invented daily and claim to have found a magic trick allowing us to eat as much as we want yet lose weight.
But here’s one worth checking out: Can eating more fruit help you shed weight?
This diet is worth a second look because we have many other good reasons to increase our fruit consumption—fruit and vegetables are an important component of a healthy diet and have a protective effect against many chronic diseases, such as heart disease, cancer and diabetes.
There’s also a plausible explanation for why eating fruit may protect against weight gain: Fruits have a relatively low-energy density, they have a lot of water and dietary fiber, and add lots of bulk. Studies show that food intake may be regulated by the weight of the food, and how long it takes to consume, therefore filling your plate with fruits would lead to greater satiety and less consumption of other foods.
A recent paper in Obesity Reviews analyzes the published studies on the association of fruits and weight loss. The authors specifically sought studies which look at fruit only, and not fruit and vegetables as one category (there are many studies showing that fruit and vegetable intake has an inverse relationship with overweight and obesity).
Of the sixteen human studies that met the inclusion criteria, eleven showed that increased fruit intake facilitated a significant reduction in body weight, decreased the risk of overweight or obesity or was associated with less overweight. The remaining five studies found no significant association, and no studies showed increased weight related to increased fruit consumption.
The studies included in this review were of three different types: Intervention studies, in which a study group is randomly assigned to receive an intervention—in this case increased fruit—and compared to a control group which receives a placebo or no intervention, prospective observational studies, in which a cohort with known exposures (in this case fruit intake) is followed for a health outcome over time (in this case weight), and cross-sectional studies, in which a population is observed at a certain point in time, looking for possible connections between, in this case, fruit consumption and weight. Each kind of study has its strengths and weaknesses.
Results from all three types of studies pointed towards an association between high fruit intake and lower weight. The authors call for large behavioral, randomized, controlled intervention studies to further clarify this issue.
Can supersizing the fruit serving increase fruit intake?
I think we’re all sold on the idea of including more fruit in our daily diet for a multitude of reasons, but many parents struggle with just how to do it—less than ten percent of kids consume their daily recommended number of fruit and veggie servings.
This brings me to another recent fruitful study, this one from the scientific journal Obesity.
Many studies show that increasing the size of the serving of food—entrees, snacks or soda—leads to increased intake, and supersizing the portion leads to supersized eating and supersized people. The authors asked the interesting question: Will supersizing the fruit and vegetables portion lead to higher intake of those in kids?
Forty-three Philadelphia-area kids aged five and six years were included in the study. They were twice fed dinner consisting of pasta with tomato sauce, broccoli, carrots, unsweetened applesauce and milk, with the portions of broccoli, carrots and unsweetened applesauce doubled in one of the meals randomly, while the pasta and milk portions stayed the same.
The results are pretty interesting:
Doubling the portion of fruit and vegetables side dishes resulted in a significant increase of 43 percent in the intake of the fruit—applesauce—but not the vegetables.
Doubling the portion of fruit and vegetables side dishes resulted in a significant decrease in the intake of the pasta dish, with the extra fruit displacing the more energy-dense pasta.
Overweight kids showed a bigger response to over-sizing the fruit and vegetables portion than normal weight kids; they ate more of the fruit and vegetables offered.
The study shows doubling the size of fruit and vegetables portions as a valid method for increasing fruit intake, but also maybe of controlling weight gain, as the fruit displaced a higher calorie food (pasta).
What about the vegetables?
A more careful look at how the vegetables were presented might offer an explanation: the broccoli and carrots were thawed from a frozen pack and served plain, with no seasoning or fat. I think even the most ardent vegetable lovers wouldn’t get too excited by those. Perhaps a more appealing preparation (broccoli sautéed with some olive oil, garlic, fresh ground pepper and salt anyone?) would have gotten a different result.
I think that if you’re plating a meal for yourself or for others increasing the size of the vegetable and fruit component is worth trying. It may very well be that the most obvious way to increase fruit and vegetables consumption is by making them show up in plenty! If they’re on the table, prepared in an appealing way, ready to eat and constantly available they’ll be what we eat when we’re hungry. That’s part of the way manufacturers of sugary drinks and junk foods make sure we consume more—they’re just everywhere and in plenty.
Food for thought!