Incorporating more whole fruits and vegetables into your diet is good for you, and variety is important. But for most people, a side of broccoli is a healthier choice than a potato.
In a new study designed to figure out the links between the intake of certain fruits and vegetables and body weight, scientists analysed the reported eating habits of 133,468 men and women in the United States over a 24-year period.
They examined whether people had gained or lost weight during four-year intervals, and then looked at which fruits and vegetables they were eating the most when they did. Only whole foods counted — no juice — and french fries and chips were excluded from the analysis, since none of those options are considered a healthy way to up your fruit or vegetable intake.
For every additional daily serving of fruit over a four-year period, people lost about a half a pound. For every additional daily serving of vegetables, people lost about a quarter pound. Those averages — unimpressive and almost insignificant changes in weight for four years — are not that interesting, unless you’re adding many servings of fruits and veggies every day.
But the kinds of plants people were eating mattered.
Increased consumption of starchy vegetables like corn, peas, and potatoes was actually associated with a gain in weight, while high-fibre, low-gluten-load vegetables seemed to be best for people concerned about their weight. Berries, apples, pears, tofu/soy, cauliflower, and cruciferous and green leafy vegetables were associated with the strongest benefits in terms of weight control.
The charts below show how certain fruits and vegetables were associated with weight change over a four-year period. The more the food was associated with weight loss, the further to the left the purple lines appear, though note that the x-axis (showing pounds lost or gained per additional daily serving of each food) is different on each graph.
It’s important to note that there are some serious limitations to this study. Participants self-reported their diets and their weights, and such reports are often prone to errors. The study population was also made up of mostly white health professionals with graduate degrees, so the results might be different in a more diverse population.
This study also cannot show that these dietary changes caused changes in weight, only that there were some interesting associations.
Researchers tried to control for other factors that may have been involved, including “smoking status, physical activity, hours of sitting or watching TV, [and] hours of sleep” as well as consumption of “fried potatoes, juice, whole grains, refined grains, fried foods, nuts, whole-fat dairy, low-fat dairy, sugar-sweetened beverages, sweets, processed meats, non-processed meats, trans fat, alcohol, and seafood.” But it’s possible, for example, that people who were eating lots of blueberries were also doing other things — not on that list — to try to lose weight, or that they had something else in common.
Only about 10% of Americans eat enough fruits and vegetables, so while the blueberries might have had nothing to do with the weight loss, eating more berries certainly can’t hurt.
The study was published in the journal PLOS Medicine.
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