Research Review:
A study in the American Journal of Clinical Nutrition shows some support for the ability of modified alternate day fasting (ADF) to facilitate weight loss and modify markers of heart health.
Subjects ate 25% of energy needs on fast days and ate ad libitum (at will) on alternate days. On fast days, subjects were instructed to consume all calories between noon and 2 p.m. This pattern continued throughout the study. Subjects were also able to meet with a Registered Dietician (RD) (explains the horrible food choices they were provided on fasting days during the first 4-week period – chicken alfredo? really?) once per week.
The cool thing about the study’s design is that for 4 weeks, the subjects were provided a meal for each fast day, and for another 4 weeks were left to complete the program without prepared food. Adherence rates remained high for subjects who completed the study, which means ADF may be a valuable tool for weight loss and health in the real-world. One drawback was that 2 people withdrew from the study due to their inability to comply with the protocol – that’s 10% of the original subject pool. I guess ADF isn’t for everyone, although that’s not surprising.
Average weight loss over 10 wks (8 wks on weight loss diet – 2 on control diet) was about 5.8% or 5.6kg (12.3 lbs). Also decreasing were BMI, body fat percentage, total and LDL cholesterol, and triaglycerol levels. Systolic, but not diastolic, blood pressure was also lowered.
This study gives us a little more evidence that ADF or intermittent fasting (IF) might be a great tool for weight loss and health interventions. However, there are some drawbacks to this study. 20 subjects is a rather small sample size, so more studies with larger samples are a must. The fact that subjects had weekly meetings with a coach (RD) most likely affected the adherence in a positive way. It would be interesting to see a study that compared an ADF plan with coaching to one without.
On a side note, the lead researcher Dr. Krista Varady commented on the subjects eating less than expected on ad libitum days and said “”I think it’s probably because their stomachs kind of shrunk.” Let’s get this straight. Stomachs don’t shrink. Feelings of satiety (fullness) change, but the physical size of the stomach does not shrink. Ugh… I can’t believe she said that.
Varady KA, Bhutani S, Church EC, Klempel MC. Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotectio in obese adults. Am J Clin Nutr 2009;90:1138-43.
Harding A. On-off fasting helps obese adults shed pounds. Reuters http://www.reuters.com/article/healthNews/idUSTRE5AB4HM20091112