You should NOT fast if you are pregnant, breast feeding, have had a severe eating disorder, or a medical issue. If you have a medical issue, especially if you’re diabetic, with a doctor’s supervision you may be able to try intermittent fasting. A great resource is the Intensive Dietary Management program, run by Dr. Jason Fung. He and his team work with diabetics all over the world to help them lose weight and reduce their need for insulin.

So, if you don’t fall into the categories above, and you have a good relationship with food right now, I’m confident you can try intermittent fasting!


It takes 8-10 hours for your liver to become depleted of glycogen (glucose) from your last meal. After that 10th hour, your liver will start to use fat to keep your metabolism and energy up (note, your liver will still be using some glucose at 10-28 hours, but the process of using fat begins). If you abstain from eating for more than 10 hours than you will be using your body fat for fuel.

Meanwhile, you’re also staying in a state of low insulin. Insulin stores body fat when levels are high, and levels get high after you eat a meal. By spending time in the fasted state, you are both burning fat for fuel and preventing the storage of body fat. It’s a win-win! Plus, fasting has been shown to have a host of other health benefits, besides fat loss. See this article for more on that.


I started with a 20-24 hour fast. I would skip breakfast, skip lunch, no snacks all day, and then break fast at around 5pm. I would have a small snack like seeds with olive oil or cheese, and then eat a full dinner about an hour or two later. I did this on alternate days: Monday, Wednesday and Friday, and the rest of the week I ate 3 square meals a day. I followed this for two weeks, and then decided to just fast to fit my schedule, since I had already seen significant fat loss.

Another method, which I do currently quite often, is a 16:8. That’s 16 hours in the fasted state, 8 hours to eat normally. For me, that typically looks like breaking fast at noon and finishing dinner by 8pm. You can adjust the 8 hours however it makes sense for you, though. If you are more of a breakfast person, you could do an 8am-4pm eating window, for example.

There’s also longer fasts, like 36 hours or 3-7 days. I have not personally tried anything beyond a 24 hour fast, due to my issues with food, and also it is very intimidating to me 🙂 I have heard from people who have done longer fasts though that days one and two are the worst, but by day three your hunger basically goes away. This means longer fasts might be easier for some, especially if you have a lot of weight to lose.


I think what worked best for me was the following:

  1. Start with trying to eat 3 meals a day and reduce junk food (include restaurant food) and snacks, this will help to reduce headaches, cravings, and the waves of hunger will be less intense once you fast. Ensure there are healthy fats in your meals to keep you fuller for longer. Eat this way anytime you are eating and not fasting in the weeks ahead.
  2. 16:8 fast. Since your hunger and fullness signals are starting to get under control, you will have an easier time sticking to two or three meals daily, and you’ll feel very satisfied and full after eating.


Hunger is inevitable when you’re not eating! But the best way to get through a fast is to do it on a day when you know you’ll be very busy, like a busy day at work or when you’re planning to reorganize your home or something. Staying busy makes it easier to ignore the waves of hunger that come (thanks to grehlin) during your regular meal times. Other ways to help you get through the hunger so you can keep fasting:

  • Drink lots of no calorie liquids to keep yourself feeling full and to keep you occupied: water, seltzer, hot or iced tea, hot or iced coffee.
  • Peppermint and green tea seem to have appetite suppressant effects
  • Seltzer is great if your stomach growls
  • Going for a walk is helpful
  • Doing a menial/tedious/all-consuming task to take your mind off of it
  • Stay away from temptation; don’t even go to the cafe and smell everyone’s lunch, just get your coffee and go back to your desk

Please note: it’s okay to feel hungry, but you should never feel ill. If you’re feeling unwell, break fast immediately. Try again in a few days. Don’t worry, I’ve broken fast early when I’ve felt it was necessary. That doesn’t make you a failure, it makes you smart. Fasting can be very healthy and beneficial, but it is NOT normal to feel sick. That’s a sign that something is wrong, and you should eat something immediately.


  • Do not use milk because it will stimulate insulin (which defeats the purpose of fasting).
  • No diet soda or artificial sweeteners–they will stimulate insulin as well. Gum and mints are included in this as well (unfortunately).
  • Exercise however your body is telling you to; for me, it felt better to stop exercising the first two weeks I started fasting, and then my energy started to come back. But it is safe to exercise exactly how you normally would, provided you feel up to it. Listen to your body!
  • It gets easier the more you do it! The first 2weeks will feel difficult, but soon you might notice you’re fasting “accidentally”, because your hunger and fullness signals will start to improve.
  • This might be obvious, but don’t tell people you’re fasting. They probably won’t understand the health benefits of fasting and will think you’re doing something unhealthy. They will immediately try to talk you out of it. If someone notices and offers you food, say, “Nah, I’m good, thank you, though.” Don’t go into the details.
  • Don’t plan to fast on days you know you’ll be expected to eat. An important work lunch is not the time to refuse a meal; tailor fasting to your schedule–that’s the best thing about it! No matter where you put your fast in your day or week, you’ll still get benefits!
  • Do not restrict your calories when you’re not fasting. You should not pay attention to calories at all. Just eat until you’re satisfied, and with a high fat diet you’ll get plenty satisfied!
  • If you’re not ready to start fasting, try just skipping your snacks. Eat three meals a day. Then as that becomes easier, skip a breakfast once. See what happens. I do think an intense regimen, like I described above, gets you “over the hump” and makes it easier to keep fasting, but if you need to build a little confidence with not eating, start small!


Fasting is the least expensive, least time consuming, least complicated weight loss tool I’ve ever used. There’s nothing extra to buy, nothing extra to make, and you can do it when it is convenient for you. Even my wife (mum of 2 and doctor of psychology) has time to fast!

It has a number of health benefits besides weight loss–and what makes it so powerful is over time, with regular fasting, your relationship with food will really improve. You will naturally get hungry less often. You will naturally have fewer cravings. You will naturally eat less, because you will get full quicker. You will be able to lose weight with much greater ease–and it will be sustainable, lasting weight loss.