Alternate-day fasting

DietUniversity of Illinois at Chicago researchers report that a modified version of a plan called “alternate-day fasting” may be a viable way to lose weight.

First, the details.

  • 16 obese adults completed were assigned to participates in each of 3 phases in the study.
    • Phase 1: 2-weeks where participants ate and exercised normally
    • Phase 2: 4-week weight loss/alternate day fast based on meals prepared for them
    • Phase 3: 4-week weight loss/alternate day fast based on self-selected food intake based on what they had learned about alternate day dieting
  • All weighed more than 210 pounds and had body mass indexes between 30 and 39.9.
  • The participants consumed 20% to 25% of their energy needs on the fast day and ate food as needed the following day.

And, the results.

  • More than 8 out of 10 participants were able to adhere to their diet during each phase of the study.
  • The response to both alternate day fast diets was about the same.
  • Body weight decreased  from 10 to 30 pounds after 8 weeks of diet; the researchers expected an average loss of only 5 pounds .
  • Percentage body fat decreased significantly from 45% and 42%.
  • Total cholesterol, LDL (bad) cholesterol, and triglycerides decreased significantly by 21%, 25%, and 32%, respectively, after 8 weeks
  • HDL (good) cholesterol remained unchanged.
  • Systolic blood pressure decreased significantly from 124 to 116 mm Hg.

The bottom line?

The authors also reported, “It takes about 2 weeks to adjust to the diet, after which people don’t feel hungry on the fast day.”

11/7/09 20:39 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.