Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
When it comes to life-changing weight loss support in Sydney, Interval Weight Loss (IWL) sits head and shoulders above the rest. Not only does it blend scientific research with real-world effectiveness, but it also helps people lose weight without unrealistic food restrictions or burnout. Unlike fad programs or one-size-fits-all dieting, IWL is grounded in evidence, adaptable to modern lifestyles, and designed for lasting change, no yo-yo dieting here.
A recent study evaluated the Interval Weight Loss program in everyday settings and showed significant and sustainable weight loss among users who stick with the model over time.
Curious how it works, why it outperforms other programs and what to expect on the journey? Keep reading. We’ll break down everything you need to know.
The magic of the IWL program comes down to one clever idea: don’t lose weight nonstop. Instead, the method alternates between one month of weight loss and one month of weight maintenance. This rhythm gives your metabolism a breather, helps stabilise hunger hormones and stops the classic ‘diet backlash’ where your body pushes back with cravings, fatigue and plateaus.
Unlike programs that rely on strict meal plans or extreme restriction, IWL focuses on behaviours you can actually maintain. You learn how to eat, move, sleep and live in a way that encourages steady fat loss without triggering the metabolic slowdown that stalls most diets.
And the results speak for themselves. Real-world data from thousands of Australians shows that after 12 months on the program:
62% of participants lost at least 5% of their starting weight
17.6% lost 10% or more
25.4% reached their personal goal weight
These outcomes highlight exactly why IWL is gaining national attention. When you combine a metabolism-friendly structure with habits that fit real life, long-term weight loss becomes not only possible, but predictable.
Scientific literature shows that weight loss programs with phases and behavioural reinforcement are linked to better long-term success. Structured maintenance phases during dieting help preserve weight loss and prevent regain by reducing metabolic adaptation and diet fatigue. In fact, a meta-analysis suggests that intensive intervention during the maintenance phase increases success in retaining weight loss over time.
Typical dieting approaches often lead to rapid loss followed by regain because the body compensates with increased appetite and reduced energy expenditure. IWL avoids this by alternating loss and maintenance cycles, which gives your metabolism time to adjust and stabilise.
IWL isn’t about weight loss weeks sandwiched between ‘diet' life and ‘real life’. It teaches sustainable habits around portion control, whole food choices, daily movement and sleep hygiene, building everyday habits rather than forcing unrealistic changes.
Rather than following strict low-calorie diets or complicated macro plans, IWL uses flexible eating patterns that fit into busy work schedules, social events and travel plans. The science shows programs that allow adaptability are more likely to be maintained long term.
The IWL framework is grounded in credible expertise and designed with oversight from qualified professionals who understand metabolism, obesity and long?term weight management.
The program was developed by Australian obesity expert Dr Nick Fuller, a leading researcher with a PhD in Obesity Treatment and a background in nutrition and metabolism, and it includes support from accredited dietitians legally registered with Australia’s professional body for dietetics.
Forget strict rules, food bans, or joyless meals. IWL emphasises balanced, real food options that are both satisfying and sustainable. The program teaches how to build meals around vegetables, proteins, and whole grains while still enjoying the foods you love, so eating well doesn’t feel like a punishment.
IWL also provides practical resources, meal examples and tips to make healthy choices easy in everyday life, helping you stay consistent without sacrificing enjoyment.
Prevent rebound weight gain
Overall, research shows that quick weight loss without structured follow-up leads to a higher likelihood of regaining weight. IWL’s alternating approach creates a buffer against this rebound effect by training both mind and body for long-term change.
Subscribers benefit from online tools, daily reminders, behaviour tracking and optional access to dietitians, which give depth and ongoing support not found in many conventional clinics.
See how IWL compares with other programs in How IWL Beats Other Weight Loss Programs.
With IWL, the path is structured, flexible, and designed to fit real life. Instead of jumping straight into extreme diets or complicated plans, the program guides you step by step.
IWL follows six key principles that help reset metabolism, prevent weight regain, and support sustainable weight loss. Rather than pushing extreme restriction, 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 often lead to plateaus or rebounds. This foundation makes the alternating loss-and-maintenance approach not just psychologically easier, but biologically smarter, setting you up for long-term success.
The first weight loss interval in IWL is all about practical, achievable changes. Participants focus on adjusting portion sizes, choosing more whole foods, and balancing meals with protein, fibre, and healthy fats.
Habit tracking is introduced to monitor behaviours that affect hunger and energy, helping participants build momentum without feeling restricted. These early steps are designed to deliver measurable results while laying the foundation for long-term success.
After completing a loss interval, IWL guides participants into a maintenance phase. This short break from active weight loss allows metabolism and hunger hormones to stabilise, reducing the risk of plateaus or rebound weight gain. It ensures that progress is maintained and that participants can continue losing weight sustainably over time.
IWL’s alternating cycles of weight loss and maintenance keep participants engaged and prevent burnout. This structure allows the body and mind to adjust naturally, supporting steady, long-term fat loss and protecting metabolic health. By rotating intervals rather than staying in constant restriction, participants are more likely to stick with the program and see consistent results.
Weight loss is just one part of IWL. The program emphasises developing everyday habits in areas that influence long-term health, including nutrition, movement, sleep, and mindset. Over time, these behaviours become routine, making it easier to maintain a healthy weight without relying on extreme diets or willpower alone.
IWL is designed for real life, meaning it’s flexible enough to adapt to work, travel, social events, or changing routines. Participants learn how to tweak intervals and maintain habits without losing progress, ensuring that the program fits seamlessly into everyday life while keeping results on track.
If you’re looking for the best weight loss program in Sydney, IWL stands out because it blends scientific effectiveness, real-world success rates, practical tools and sustainable lifestyle changes. Backed by research, it’s clear why IWL is more effective than traditional diets and clinic programs.
With thoughtful habit building, flexible routines and evidence on your side, IWL isn’t just a program. It's a path to lasting change.
Ready to see real, lasting results? Start your journey with the Interval Weight Loss Program today and take the first step towards a healthier, more sustainable you.
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.