Eat Fruits and Vegetables to Reduce Your Calories

A diet rich in fruit, veggies, and whole grains lowers the risk of several diseases. Research shows plant-based diets rev up metabolism for weight control, too.

If you know any vegetarians or vegans, you’ve probably noticed they are almost always slim. It turns out, it’s not necessarily due to eating fewer calories.

Researchers have found eating a plant-based, low-fat diet based on fruits, vegetables, and whole grains — with no calorie limit — revs up metabolism so much it increases the number of calories burned by almost 20 percent. That style of eating may also cause LDL (low density lipoprotein), the “bad” artery clogging cholesterol to plummet.

The study findings, published in JAMA Network Open by the Physicians Committee for Responsible Medicine and Yale University researchers, could be groundbreaking for millions of Americans struggling with excess weight. After all, there is an epidemic of Americans who are overweight, almost 43 percent of them obese, according to the the Centers for Disease Control and Prevention (CDC).

“Over the course of years and decades, burning more calories after every meal can make a significant difference in weight management," says study author Hana Kahleova, MD, PhD, director of clinical research for the Physicians Committee for Responsible Medicine.

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Evidence plant-based diets zap calories

The study randomly assigned research volunteers (who were all significantly overweight and had no history of diabetes) to either a dietary intervention group or a control group. Then, for about four months, the participants in the intervention group ate a low-fat, plant-based diet based on fruits, vegetables, whole grains, and legumes. There was no limit to the amount they could eat and no calorie limit. The control group, on the other hand, kept eating the way they usually did, without dietary changes.

None of the research subjects altered their exercise routines or medications, unless their personal doctors ordered a change in prescription drugs.

To measure how many calories the people in both groups burned after eating a meal at the beginning at the study’s beginning and end, researchers used indirect calorimetry, a technology that measures respiratory gases linked to metabolism.

The control group’s after-meal calorie burning didn’t change significantly and they didn’t lose weight. But the results showed the people in the plant-based meal group increased their after-meal calorie burning by an average of almost 20 percent.

The metabolism-boosting power of the plant-based meals resulted in an average loss of 14 pounds within 16 weeks for the research subjects who ate vegan and vegetarian meals. Some dropped significantly more excess pounds.

“I plan to stay on this diet for good. Not just for 16 weeks, but for life,” reports study participant Sam T., who lost 34 pounds and improved his metabolism during the 16-week study. Since the study concluded, Sam has continued a plant-based diet, reached his goal weight, and began running half-marathons and marathons.

How the benefits of plant-based meals might prevent diabetes

The veggie, fruit, and whole-grain eaters had another change in their bodies that the control group didn’t experience. Those in the plant-based group saw significant losses of body fat, including visceral fat — the dangerous fat that can accumulate around internal organs.

So, for another part of the study, Yale University researchers Kitt Petersen, MD, and Gerald Shulman, MD, used high-tech magnetic resonance spectroscopy to measure the amount of fat accumulated inside muscle and liver cells in some of the research subjects.

The findings revealed those eating plant-based meals reduced fat in their liver cells by 34 percent and fat inside muscle cells by 10 percent. The research subjects in the control group, however, showed no significant changes in accumulated fat in muscle and liver cells.

This finding is important, the research team concluded, because fat building up in these cells is associated with both type 2 diabetes and insulin resistance, which raises the risk for type 2 diabetes.

"When fat builds up in liver and muscle cells, it interferes with insulin's ability to move glucose out from the bloodstream and into the cells," study author Kahleova explains. "After just 16 weeks on a low-fat, plant-based diet, study participants reduced the fat in their cells and lowered their chances for developing type 2 diabetes."

Bottom line? Plant-based meals can reduce health risks — not just weight

The research volunteers who ate plant-based meals also saw their total cholesterol levels plummet by an average of almost 20 mg/dL — and most of that reduction was in the “bad,” heart-disease linked LDL cholesterol.

“Not only did the plant-based group lose weight, but they experienced cardiometabolic improvements that will reduce their risk for type 2 diabetes, heart disease, and other health problems,” says Kahleova.

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