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Fast-5 Diet Summary

Eat within five consecutive hours.
That’s it—that's the basic summary: eat within five consecutive hours. “Eat” means consume calories according to your appetite. It does not mean eat constantly for five hours, nor does it mean eat as much as you can. During the five consecutive hours (the “eating window”), eat as much as you’re hungry for, and eat what you want to eat. Consuming liquids with calorie content counts as eating, so only calorie-free beverages are permitted during the fasting period - no juice, protein shakes, etc. As long as you keep at least a nineteen-hour fast daily and eat within five or fewer consecutive hours, you’re within the guidelines of the Fast-5 program. Any window of five consecutive hours can be used.

What to expect:
Expect zero weight loss in the first three weeks, which is the adjustment phase. You may even see weight gain during this period due to compensatory overeating. Weight measurement during this time is not recommended, but many people can’t resist, so don’t expect a loss. Three weeks after starting the Fast-5 program, you should see an average of a pound per week loss. That means over the course of four weeks, you should see four pounds lost, but the loss may not be evenly spread from week to week; it can be two pounds one week, none the next, then two again, and so on.
Some people see more rapid weight loss, even in the first three weeks. That’s not a problem, but may not be seen by everyone, and is less likely for someone who’s already been maintaining a low-carb diet. An early loss of several pounds early is likely to be mostly water, so if you see a large early loss, do not expect to see the same rate in later weeks.

How to start:
There are two ways to start, “cold turkey” and a gradual “adjustment” approach.

1. Cold Turkey
In a cold turkey start, one simply chooses to not eat until the eating window opens. This approach is usually effective but may require a number of “close-but-not-quite” days before finally reaching the target time. Using this approach, the third, fourth or fifth day is typically the hardest to get through, and after this “crunch” day, the days get easier quickly.

Key to remember: If you slip and don’t reach your goal, don’t give up. Getting close to your goal pushes your body to adapt, which can make it easier to reach your goal on your next try. Slips are a normal part of adjustment.

2. Adjustment

  • A. Standard Adjustment

    In the adaptation approach (extensively described in the book), the time one first eats (called break-fast and pronounced “brake-fast” to avoid confusion with breakfast) is gradually pushed back. The time of break-fast is pushed back by the same interval (half an hour or an hour) every day or every few days until it is the desired window opening time.

  • B. "Ratchet" Adjustment

    One can also adapt using the faster “ratchet” approach, in which you don’t eat until at least 15 minutes later than yesterday’s break-fast time, but if you’re not truly hungry at that time, you wait until you are. With this approach, you postpone break-fast by whatever time increment your body’s ready for. On some days break-fast may be 15 minutes later than the day before, and on other days it may be an hour or more later, but it doesn’t fall back.

Key to remember: Same as the cold turkey approach: If you slip and don’t reach your goal, don’t give up. Getting close to your goal pushes your body to adapt, which can make it easier to reach your goal on your next try. Slips are a normal part of adjustment.

Effects and Side Effects
The Fast-5 way of eating works because it restores appetite to an appropriate level for the amount of stored energy (fat) you have and the amount of energy you expend in a day. You take in less food so your body burns more fat. Binge eating may occur during the adjustment phase of the program, but doesn’t typically persist.

People on a Fast-5 way of eating have reported the following:
Inches before pounds—Inches seem to disappear before the weight comes off. Probably due to fat redistribution, this means a Fast-fiver typically will see loosening of belts or pants before the weight loss is seen on the scale.

Feeling cool or cold when they’d usually be comfortable —This occurs during the fasting period due to the absence of heat generated as a byproduct of digestion of the usual meals. Digestion is metabolic activity, but the energy burned by digesting food is less than the energy that gets stored, resulting in a net gain of calories and fat. While the absence of digestive heat may mean wearing an extra layer in cold weather, it also means greater comfort in warm or hot weather. After starting Fast-5, the heat byproduct of digestion may be more noticeable after break-fast because it hasn’t been going on constantly.

Decrease in symptoms of inflammatory and other diseases—Fast-fivers have reported diminished symptoms of: rheumatoid arthritis, multiple sclerosis, asthma, congestive heart failure and a reduction of insulin requirement for type 2 diabetes.

Saving money and time—Fewer meals, less food, and less time spent preparing meals means more time and money for you to spend as you wish.

Please read the FAQ (Frequently Asked Questions) file for more information.