The Food Experiment: Types of Intermittent Fasting

There are several types of intermittent fasting. They all have a basis in physiology, and all can help you achieve your goals in the lifestyle experiment. But you will likely find some easier to do than others. As with any self-experiment, you will need to determine which interventions are best for you.

Here are the most popular methods for intermittent fasting:

• The 16/8 method (aka Daily time-restricted fasting): Also called the Leangains protocol, this involves an 8-hour eating period and a 16-hour fasting period. Some people do this by skipping breakfast, but you can also do the reverse and skip dinner or eat early.

• Eat-stop-eat: This involves fasting for 24 hours once or twice per week. Because this is a slightly more advanced version of fasting, you should only try this if you’re pretty comfortable with the practice.

• The 5:2 diet: With this method, you consume only 500–600 calories on two nonconsecutive days of the week but eat as usual the other 5 days.

• Alternate Day Fasting: Eat a normal diet one day and either completely fast or have one small meal (less than 500 calories) the next day.

Intermittent fasting has been shown to improve insulin sensitivity and reduce inflammation. It has been shown to help with weight loss and improve brain health.

Patients often tell us that the "easiest" type of intermittent fasting is the 16/8 method. The hardest is something like the 5/2 diet where you fast (or nearly fast) for 2 full days. Unfortunately, we also find that 5/2 is usually more effective than 16/8 or any type of "timed daily eating". We believe this is because your metabolism can quickly adapt to the timed daily eating and you never really make the jump over from carbohydrate burning to fat burning.

As have already discussed, the whole idea of intermittent fasting, from the perspective of your metabolism, is that you are trying to make the conversion over from burning primarily carbs to burning fat. You know when you have started burning fat when ketones (molecules that come from the breakdown of fat globules) start to appear in your urine. We recommend getting some ketone test strips from the pharmacy and using them to ensure that you have entered fat burning mode.