What is intermittent fasting?

Is intermittent fasting and time restricted eating the same thing?

You may remember there was article on time restricted eating back in the November 2023 Membership Matters edition. Both approaches are similar in that they have a fasting element to them, and don’t tell you what to eat. However, outlined below are some of the key differences to them both.

• Time-restricted eating

  • Is a strategy where food and energy intake is limited to a set eating window.

  • Outside of the eating window, you are required to fast.

  • For example, the 16:8 approach, means 16 hours of fasting and an 8-hour eating window. This could mean your breakfast might start at 10am and your last meal is at 6pm that day.

  • The fasting period and eating window times are the same, every day.

• Intermittent fasting

  • Is an approach to eating that recommends alternate days of structured fasting and then days with no fasting at all.

  • Fasting periods can change and there is no one specific way to do this.

  • Fasting periods are often not total fasting, as food and drinks are allowed, you are just encouraged to restrict your energy (kilojoule/calorie) intake on those days.

How does intermittent fasting work?

To put it simply, intermittent fasting is the practice of swapping times of your usual eating with extended times of small amounts or no food intake at all.

Most diets only focus on what to eat. Intermittent fasting is different, as on the non-fasting days, there are no rules or restrictions on what you should and shouldn’t be eating. Having said that, to get the best results, it is recommended to focus on enjoying food and choosing more nutritious choices. Drinking water during fasting periods is also advised to avoid dehydration.

Some of the more common intermittent fasting approaches are listed below:

The 5:2 diet

The 5:2 approach, means that for five days of the week you can eat and drink what you like, and the remaining two days of that week you restrict your energy (kilojoule/calorie) intake. For those two ‘fasting’ days of the week, it is often recommended to restrict your energy intake to around 2,000 to 3,000 kilojoules per day. It is often encouraged not to do two consecutive days of fasting.

The Eat-Stop-Eat method

The Eat-Stop-Eat method of fasting involves fasting for a full 24 hours one or two days per week. This approach differs to the 5:2 diet as for these one or two days of the week require full fasting. So, no food or drinks that contain energy can be consumed, but water is permitted.

Alternate day fasting

Is exactly what it sounds like, where the goal is to fast every other day and on non-fast days you can eat what you like. For example, one day is a full fasting day and the next day is your usual day of eating.

Some approaches encourage extended fasts that may go for several days but these should only be done under medical and/or dietitian supervision.

The final say:

The health benefits for intermittent fasting are still not well known and more research is needed. The research on type 1 diabetes is very limited. For those with type 2 diabetes, early research has shown:

• Improved blood pressure, cholesterol and lipid levels.
• Decrease in body weight or waist measurement.
• Improved glucose levels.

It is not fully understood why glucose levels are improved. However, this is probably due to the lowering of energy intake on fasting days, and a possible reduction in body weight, decreasing insulin resistance.

Intermittent fasting will not suit everyone. It would not be suitable for anyone who is:

• pregnant or breast feeding,
• undergoing cancer treatment,
• underweight,
• or has a history of disordered eating.

If you are thinking of giving this approach a try, please speak with your healthcare team first. Especially if you are taking diabetes medications and/or insulin.

If you would like to see a dietitian, you can now make a booking online at our Diabetes Victoria Clinic, or please call 1300 153 123  for more information. As a Diabetes Victoria member, you will receive a discount for any appointments you attend.

For more general advice and enquiries, contact NDSS Helpline on 1800 637 700.