Guidelines for Progressive Intermittent Fasting
‘Doc, how should I start intermittent fasting if I’ve never done it before?’
I get this question quite often. The truth is that most people will suffer no serious health issue if they suddenly fast for 20-24 hours, even if they’ve never fasted before. However, the chance of feeling unwell or very hungry during the fast is much more likely.
If you are new to intermittent fasting, I would recommend starting low and going slow. That way, your body will gradually adjust to longer and longer periods of going without food. You will be much less likely to struggle with hunger, cravings, dizziness, headaches or mood changes associated with fasting if you get used to it over time.
Naturally, some people can adapt more quickly than others, but for anyone who wants to try intermittent fasting for the first time, here is the schedule I would suggest:
WEEK 1: 12-hour fast every day
For example: Stop eating at 18h30 and have your breakfast the next day at 06h30. Of course, you don’t have to wait for the clock to strike the precise moment to dig into your breakfast, but you get the idea. Have your normal meals and snacks within the 12-hour ‘eating window’ between 06h30 and 18h30.
WEEK 2: 2 days x 14/10 (aka Brunch fast), maintaining 12-hour fast on other days
Extend your fast by a couple of hours on a couple of days this week.
For example: Finish your dinner at 19h00 and have a ‘brunch’ at 09h00 the next day. Have lunch and dinner as usual if you feel hungry.
WEEK 3: 2 days x 16/8, maintaining 12-hour fast on other days
On 2 days this week, completely skip breakfast and eat at lunchtime.
For example: Finish your dinner at 19h00 and eat again the following day at around 13h00.
WEEK 4: 2 days x 18/6, maintaining 12-hour fast on other days
On 2 days this week, extend your fast to 18 hours if you can.
For instance: Finish your dinner at 18h30. The next day, break your fast at 13h30.
WEEK 5: 3 days x 18/6, maintaining 12-hour fast on other days
This week: fast for 18 hours on 3 days to help your body adjust to more frequent longer fasts. Fasting for 18 hours or longer helps your brain and muscle tissues adapt to using ketones for energy.
WEEK 6: 2 days x 18/6, 1 day x 20/4, maintaining 12-hour fast on other days
This week: Maintain an 18-hour fast on 2 days. And then do a 20-hour fast on another day.
An example of a 20-hour fast: Finish your dinner around 19h00. Skip breakfast the next day. Skip lunch as well and break your fast around 15h00. You can have a full meal at this time and a lighter meal at dinner, or a protein- and fat-based snack now to satisfy your hunger and maintain ketosis, then your full dinner later.
WEEK 7: 2 x 18/6, 1 day x 24-hour fast, maintaining 12-hour fast on other days
This week:
Fast for 18 hours on 2 days. Then try a 24-hour fast on another day.
An example of a 24-hour fast: Finish dinner at 18h00. Skip breakfast and lunch the next day. And break your fast at 18h00. You would have fasted for a full 24 hours.
Remember: When you break your fast (especially after longer fasts), include plenty of vegetables, some protein and healthy fats like olive oil, nuts and seeds, cheese, avocado and coconut to maintain ketosis. Avoid refined or fast-release carbohydrates like cereal, bread, pasta, noodles, potatoes or polenta as these will immediately trigger release of insulin and fat-storage mode.
If you want to benefit the most from intermittent fasting, make sure your ‘break-fast’ meal is healthy and nutritious. Have a look at the section on ‘Healthy Plate’ for more details on nutritious meal planning.