One study had two 8-week phases in which 49 healthy men took 150 mg of quercetin per day or a placebo, and then did the reverse. After the quercetin phase, levels of HDL, the “good” cholesterol, increased by 4.5 percent. Total circulating fat (triglyceride) levels also declined, and systolic blood pressure decreased by an average of 5.7 points (mmHg).
Researchers also measured changes in weight, waist circumference, and body mass index (BMI) scores and found that overall, waist size decreased after the men took quercetin. But not all men lost weight. Doctors found that only men with a specific variation of a fat-binding protein, apolipoprotein E 3/3, lost weight, waist size and had better BMI.