Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
Diet trends come and go, but Interval Weight Loss (IWL) is making waves for all the right reasons. This science-backed approach helps people lose weight without the usual struggle of strict diets, calorie counting, or excessive workouts. Instead, it follows a structured yet flexible method that works with your body's natural instincts.
A 2023 study on Interval Weight Loss (IWL) found that 62% of participants dropped at least 5% of their body weight—and kept it off. The CSIRO Total Wellbeing Diet saw almost half its members hit that same milestone in just 12 weeks, while Weight Watchers (WW) Online users lost around 2.7 kg on average.
This result highlights IWL’s impressive success rates, proving its effectiveness for long-term weight management. But what makes this approach different from traditional dieting methods?
The 2023 research from the University of Wollongong (UOW) put Interval Weight Loss to the test in a real-world setting, and the results speak for themselves. Of those who stuck with the program for a year, 25.4% reached their goal weight, 17.6% lost at least 10% of their body weight, and 62% shed 5%. These numbers might not sound flashy compared to crash diets promising rapid results, but here’s the kicker: these participants weren’t just shedding kilos; they were keeping them off.
Unlike typical diets that lead to a frustrating cycle of weight loss and regain, IWL’s structured approach prevents the body from triggering its survival instincts. The study highlighted that alternating weight loss with maintenance phases helped participants avoid metabolic slowdowns and weight-loss plateaus, which are common pitfalls in traditional dieting.
Even better, the research showed that IWL isn’t just about the number on the scale. Participants reported improved overall health, better eating habits, and an easier time sticking to the program compared to restrictive diets. With scientific backing and real-world success, IWL proves that weight loss doesn’t have to be a battle—it just needs the right strategy.
IWL isn't about quick fixes—it’s a long-term approach based on how our bodies evolved to maintain weight. It follows six key principles that help reset metabolism, prevent weight regain, and support sustainable weight loss. Unlike restrictive diets, it encourages a balanced lifestyle that’s easy to maintain.
By focusing on gradual weight loss, eating whole foods, and aligning habits with natural rhythms, IWL allows the body to adapt without triggering survival mechanisms that lead to plateaus or rebounds.
You Can’t Fight Evolution
Your body is wired for survival, which means it resists rapid weight loss. When you drop kilos too quickly, your metabolism slows down to conserve energy, making it harder to keep the weight off. IWL works by alternating periods of weight loss with maintenance phases, which allows your body to adjust without triggering this defence mechanism.
This approach keeps your metabolism steady, reduces cravings, and makes long-term weight loss more achievable. Instead of shocking your system, it eases your body into a healthier weight naturally.
Whole, unprocessed foods should always come first. Processed meals packed with artificial additives can mess with your hunger signals and lead to overeating. That’s why IWL encourages sticking to foods in their most natural state—think fresh veggies, lean proteins, whole grains, and healthy fats.
These nutrient-rich choices keep you full longer, balance blood sugar, and support overall well-being. Retrain your brain to rely on nature’s treats; the more whole foods you eat, the less you’ll crave processed ones. Plus, by focusing on real food, you fuel your body without stressing over calorie counting or meal replacements.
Eating a variety of colourful fruits and veggies is one of the easiest ways to load up on essential vitamins, minerals, and antioxidants. Each colour brings something unique to the table, so the more variety, the better!
For example, bright orange foods like carrots and pumpkins are packed with beta-carotene, while dark leafy greens give you a boost of iron and folate. Fill your plate with veggies, eat more than you're used to, and remember—no foods are off-limits! It’s all about balance, helping you fuel your body for better digestion, steady energy, and healthy weight loss.
Mindful eating is a big part of IWL, and something as simple as using chopsticks can help you slow down, giving your brain time to register fullness before you overeat. Eating too fast can lead to extra calories before your body even realises it's had enough.
A great approach is to eat big to small throughout the day; start with a hearty breakfast, a balanced lunch, and a lighter evening meal. Try using chopsticks at dinner to naturally pace yourself, or swap in smaller utensils and take mindful pauses. The goal? Better digestion, portion control, and a healthier relationship with food!
Exercise doesn’t have to be intense to be effective. IWL encourages daily movement that feels natural and enjoyable—walking, swimming, cycling, or even dancing. The key is to make activity a regular part of your routine, not a chore.
Staying active keeps your metabolism going, supports heart health, and helps manage stress. During weight loss months, focus on variety—mix up your workouts to keep things interesting and engage different muscle groups. Even simple activities like gardening or taking the stairs add up. What matters most is staying consistent and keeping your body moving in ways you enjoy.
Believe it or not, your sleep habits play a huge role in weight loss. Late-night scrolling? It’s doing more harm than you think. Blue light from screens messes with melatonin, which makes it harder to fall asleep. And poor sleep throws hunger hormones out of whack, leading to cravings and weight gain.
IWL encourages switching off all tech before bed and filling that time with reading, hobbies, or even tackling your to-do list—anything that helps you wind down naturally. Dimming the lights and creating a calming nighttime routine can make all the difference. Better sleep = better metabolism, lower stress, and a healthier you!
The IWL approach offers more than just weight loss; it promotes a healthier lifestyle that’s easy to maintain.
Forget crash diets that leave you starving and back at square one. IWL takes a smarter approach, letting your body adapt naturally so you avoid rapid weight loss (and regain!). With alternating loss and maintenance phases, it’s designed for long-term success, not just a quick fix.
This means no extreme restrictions, no frustration, just steady progress you can actually maintain. Because keeping the weight off is just as important as losing it.
Hitting a weight-loss plateau can be frustrating, but IWL is designed to keep your metabolism on track. By giving your body time to adjust, it prevents the slowdowns that often derail progress. The secret? Alternating between weight loss and maintenance to keep things balanced and sustainable.
This way, you’re not just losing weight—you’re setting yourself up to keep it off for good!
Most diets don’t work long-term because they ignore how the body fights to regain lost weight. IWL takes a more sustainable approach—by building in maintenance phases, it helps lock in new habits before moving to the next weight-loss stage. This steady, stress-free method makes it easier to stick with your progress and avoid slipping back into old routines.
IWL goes beyond just shedding kilos; it helps you feel your best. With a focus on whole foods, mindful eating, and staying active, it supports better digestion, steady energy levels, and overall well-being, inside and out.
No complicated meal plans, no extreme exercise routines—just simple, natural habits that fit into everyday life. Whether you’re at home, travelling, or eating out, IWL is flexible and practical.
IWL isn’t just another fad—it’s supported by scientific research and designed by experts who understand how the body naturally regulates weight. Studies confirm its effectiveness in helping people lose weight without restrictive dieting.
The 2023 research from the University of Wollongong (UOW) put Interval Weight Loss to the test in a real-world setting, and the results speak for themselves. Of those who stuck with the program for a year, 25.4% reached their goal weight, 17.6% lost at least 10% of their body weight, and 62% shed 5%. These numbers might not sound flashy compared to crash diets promising rapid results, but here’s the kicker: these participants weren’t just shedding kilos; they were keeping them off.
Unlike typical diets that lead to a frustrating cycle of weight loss and regain, IWL’s structured approach prevents the body from triggering its survival instincts. The study highlighted that alternating weight loss with maintenance phases helped participants avoid metabolic slowdowns and weight-loss plateaus, which are common pitfalls in traditional dieting.
Even better, the research showed that IWL isn’t just about the number on the scale. Participants reported improved overall health, better eating habits, and an easier time sticking to the program compared to restrictive diets. With scientific backing and real-world success, IWL proves that weight loss doesn’t have to be a battle—it just needs the right strategy.
Ready to start? Follow these steps to integrate IWL into your life.
Familiarise yourself with the six key principles:
gradual weight loss
whole foods
variety
mindful eating
daily movement
healthy sleep.
Aim for small, steady progress rather than rapid weight loss. This prevents your body from triggering survival mechanisms that make weight loss harder.
Focus on whole foods, including lean proteins, healthy fats, and fibre-rich carbs. This ensures steady energy levels and long-term satiety.
Move daily in a way that feels enjoyable. Walking, stretching, or light strength training are all effective ways to stay active.
Monitor your weight, energy levels, and habits. If progress slows, tweak your routine without resorting to drastic changes.
IWL is designed for long-term success, so patience is key. Stick with the method, and the results will follow.
Interval Weight Loss is gaining recognition as Australia’s No. 1 diet for a reason. It’s sustainable, backed by research, and designed to work with your body, not against it. By following its principles, you can achieve steady weight loss without extreme restrictions or setbacks.
Ready to give it a try? Small, consistent changes can lead to big results.
Dr Nick Fuller is the founder of Interval Weight Loss and is a leading obesity expert at the University of Sydney with a Ph.D. in Obesity Treatment. Dr Fuller is also the author of three best-selling books and his work been published in top ranked journals in the medical field, including JAMA, Lancet and American Journal of Clinical Nutrition.