The largest study ever comparing obesity rates found regular meat eaters topped the charts with an average body mass index (BMI) of 28.8—close to being obese. Flexitarians, who ate meat more on a weekly basis rather than daily, did better at a BMI of 27.3, but were still overweight. With a BMI of 26.3, pesco-vegetarians (people avoiding all meat except fish) did better still. Even U.S. vegetarians were marginally overweight, coming in at 25.7. The only dietary group found to be of ideal weight were those eating strictly plant-based (the “vegans”), whose BMI averaged 23.6.
At issue isn’t only the number of calories, but where those calories come from. A dietary quality index was developed that simply reflects the percentage of calories people derive from nutrient-rich, unprocessed plant foods on a scale of 0 to 100. The higher the score, the more body fat may be lost over time and the lower the risk may be of abdominal obesity, high blood pressure, and high cholesterol. The standard American diet was found to rate 11 out of 100. According to U.S. Department of Agriculture estimates, 32 percent of our calories comes from animal foods, 57 percent from processed plant foods, and only 11 percent from whole grains, beans, fruits, vegetables, and nuts.
With whole-food, plant-based eating, there may be no need for portion control or counting calories because most plant foods are naturally nutrient dense and low in calories. Moreover, calorie for calorie, those eating plant-based appear to get higher intakes of fiber, calcium, magnesium, iron, potassium, and A, C, E, and B vitamins.
EPIC-PANACEA, the largest study ever to investigate eating meat and body weight, found meat consumption was associated with significant weight gain even after adjusting for calories, meaning if two people ate the same number of calories, the person eating more meat might, on average, gain significantly more weight.