Intermittent fasting: 16:8 or 5:2


Studies show fasting can help to reduce inflammation, control blood pressure and support modest but significant weight loss over time. With our social calendars largely on pause right now, and the opportunity to dictate your own eating schedule if you are working from home, lockdown may be an appropriate time to attempt a fasting regime.

A lifestyle, not a diet

Professor Mark Mattson, a Professor of Neuroscience at John Hopkins University recently authored a review paper published in the New England Journal of Medicine on intermittent fasting and its role in health, ageing and disease. He says the first thing to know about fasting is that it should not be thought of as a short-term regime. “Intermittent fasting should not be considered a ‘diet’, rather an eating pattern that is committed to long term in order to reap the potential benefits.”

The one-month rule

“Findings from my research show that at least 80 per cent of people who are able to switch to an intermittent fasting eating pattern for at least one month are able to incorporate the new eating pattern into their lifestyle long term.” Mattson says daily time-restricted eating, in which all calories are consumed within a six or eight-hour period each day, leaving 16-18 hours without food is easier than the 5:2 method for most people. “A key practical point is that it can take up to a month to adapt to if such that the person is no longer hungry during the times they had previously been eating.”


If you are currently battling a constant desire to snack, or lacking structure with your day and your food intake as a result, adopting a fasting regime may be a practical solution. The key is identifying which of the various fasting methods will best suit your lifestyle and be sustainable long term.

The 16:8 model

This involves a daily fast of 16 hours and an eating ‘window’ where two meals are usually consumed. You can choose the times of day it suits you to eat, say brunch and early dinner, or lunch and dinner and then allow 14-18 hours before you eat again – most of which time you will be asleep. You are then able to enjoy substantial, satisfying meals in this 6-8 hour time window and will be well and truly hungry again 14-18 hours later.

So what does a typical eating day look like? Eggs and toast with coffee for a late breakfast or lunch meal, followed by a pasta or stir fry or roast meal for an early dinner – two substantial meals which take the focus away from constant snacking.

The 5:2 model

In the case of following the 5:2 regime, you will have five regular eating days and two non-consecutive fasting days, where no more than 500-600 calories are consumed. On the low calorie days you can take the focus off food, while eating more freely on the other five days without restricting calories. Of course, eating “freely” does not mean you can eat anything. Overeating and bingeing on junk food on your non-fast days will jeopardise weight loss.


Unlike many diets which require constant focus and vigilance as well as much food prep, the 5:2 method can be an easy regime to follow. In food terms, an example fasting day includes a small coffee and boiled egg, a miso or broth-style soup for lunch and a light salad for dinner.

Dr Michael Mosley’s most recent weight loss plan, The Fast 800, combines various principles of intermittent fasting, time-restricted eating and the Mediterranean diet. The plan involves eating 800 calories a day for a minimum of two weeks, and then moving to the “new” 5:2 plan which suggests two 800-calorie “fasting days” and a Mediterranean-style diet for the rest of the week. As with all diets, you should speak to your GP before commencing a fasting regime.

In my experience clients find either the 16:8 approach or relatively strict fasting on just two days each week much easier to follow than needing to limit daily calories to 800 (the recommended daily calorie intake for an Australian adult is 2,000) for an extended period of time. A key component of achieving success with any fasting regime is matching the dieting approach to a client’s eating preferences. Most prefer to limit their hours of eating rather than severely limit their calories.

Any diet will work if it is followed, but the issue is that few diets are sustainable. The standout feature of intermittent fasting is that it offers a pattern of eating that can be tailored to an individual’s lifestyle without the need for food preparation. And as many of us battle to regain control over our eating in lockdown, fasting may be a simple way to diet without dieting at all.

Susie Burrell is a dietitian and nutritionist.

Sign up to our Coronavirus Update newsletter

Get our Coronavirus Update newsletter for the day’s crucial developments at a glance, the numbers you need to know and what our readers are saying. Sign up to The Sydney Morning Herald’s newsletter here and The Age’s here.

Most Viewed in Lifestyle



Please enter your comment!
Please enter your name here