The Many flavors of Intermittent Fasting
Updated: Aug 21, 2021
There’s little evidence to suggest one form of IF(Intermittent Fasting) is better than another and no evidence suggesting IF is right for everyone (ask your registered dietitian for thoughts before diving in). Here’s a look at some common approaches.
Time- restricted fasting: Majority of the day is spent in the fasted state with specific hours allotted for eating. Popular methods include the 16:8 method (16 hours fasting: 8 hours eating) with ranges existing from a more liberal ratio (12:12) to pushing the limits of IF (20+:4).
Research on time-restricted fasting has found reductions in fasting glucose, and improvements in LDL- and HDL-cholesterol. Self-reported hunger was higher in the morning for those consuming a single meal per day, and subjects did not report becoming accustomed to this hunger over the course of the study.
Alternate- day fasting: Alternating between days of fasting (energy-free fluids only) and feasting (no rules).
Research comparing alternate day fasters to individuals on a standard, reduced-calorie diet found that there was no difference in weight loss or weight maintenance over the course of one year. Like time-restricted fasting, alternate day can lead to modest weight loss with possible improvement in metabolic parameters but hunger on fast days is intense and is unlikely to improve over time.
Modified fasting: Across the week, 5 days typical eating and 2, non-consecutive days of intake limited to 20 -25% of calorie needs.
Research suggests that this method results in weight loss, with modest and mixed effects on blood sugar control, blood lipid levels, and inflammatory markers. There is little evidence to suggest that this method produces superior weight loss or metabolic changes in comparison to standard energy restriction regimens.