Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
You’ve cut calories, exercised more, and followed every tip, but the scale won’t budge. Or worse, the weight comes back. It’s frustrating, but it’s also common.
Losing weight is hard enough, but keeping it off is even harder. A meta-analysis of 29 long-term studies found that more than half of the weight lost was regained within two years, and over 80% was regained within five. It’s a common cycle, and it’s not because people aren’t trying hard enough. More often, it’s because the usual approach to weight loss isn’t sustainable.
If you’ve been doing ‘everything right’ and still not seeing results, it might be time to take a different approach. One that’s grounded in how the body actually works, not just in pushing harder.
Here are six common reasons your efforts might be stalling (and what you can do about them).
It’s surprisingly easy to underestimate how much you’re eating, especially when it comes to snacks, restaurant portions, and ‘health’ foods that seem innocent but pack more calories than expected. Research shows that even dietitians, who are trained professionals who regularly record food intake, can underestimate their calorie intake, though generally less than the average person. In one study, dietitians underreported by about 10%, while non-dietitians underreported by nearly twice as much.
If you're not tracking what goes on your plate (and into your mouth), it's easy to overshoot your energy needs. Portion sizes have grown significantly over the past few decades, and so have our plates and bowls. That, combined with frequent dining out and reliance on pre-packaged ‘healthy’ snacks, can lead to chronic overconsumption without you even realising it.
Exercise has plenty of benefits, but it’s not a free pass to eat whatever you want, nor is it a silver bullet for weight loss. In fact, many people significantly overestimate how many calories they burn during a workout, by up to 3 or 4 times, and end up eating more calories than they expended afterwards, even when trying to match it precisely.
On the flip side, extreme dieting or skipping meals can backfire. Your body shifts into energy-conservation mode, and over time, this can lead to muscle loss, reduced metabolic rate, and a higher risk of weight regain. Sustainable weight loss requires a balance, not pushing harder on one end while neglecting the other.
Sleep and stress aren’t just ‘lifestyle’ factors. They are key players in your body’s hormonal orchestra. Lack of sleep disrupts leptin and ghrelin, the hormones that control hunger and satiety. At the same time, chronic stress can elevate cortisol, which has been linked to increased abdominal fat and cravings for high-energy foods.
Struggling to get consistent sleep or constantly wired? Your body might be resisting weight loss without you realising it. Sleep is a vital part of weight management. Here's why.
If you’re ticking all the right boxes but the scale won’t budge, it’s worth checking if there’s an underlying medical issue. Thyroid disorders like hypothyroidism can slow metabolism, while conditions like polycystic ovary syndrome (PCOS) can affect insulin sensitivity and fat storage. These are just some of the common causes of unexplained weight gain that can make weight management feel like an uphill battle.
Some medications, such as antidepressants, beta-blockers, or corticosteroids, are also known to cause weight gain or make weight loss more difficult. And when hormones are involved, the usual calorie-in, calorie-out approach may not work as expected. If you suspect your body is out of sync, it might help to explore the signs of hormonal weight gain and speak with a health professional about next steps.
Protein is essential for preserving muscle mass, especially when you’re in a calorie deficit. A controlled study found that individuals who consumed protein at levels 2 to 3 times higher than the recommended dietary allowance lost more fat and preserved more lean mass compared to those who only met the recommended dietary allowance, even though all groups lost the same amount of total weight. A higher protein intake helps with satiety, supports recovery, and prevents your body from burning lean tissue as fuel.
Strength training goes hand-in-hand with that. Without it, your weight loss might come at the cost of muscle, which can lower your resting metabolic rate. Building and maintaining muscle helps you burn more calories at rest and supports long-term weight regulation.
Weight loss isn’t linear. Some weeks you’ll see progress, others you won’t. But consistency, not perfection, is what drives real change. When habits fluctuate or you revert to old routines on weekends or during ‘bad’ days, it can stall your momentum.
And if you’re only watching the scale, you might miss signs that your body is changing in a good way: better sleep, more energy, clothes fitting differently, or healthier lab results. The number might stay the same even when you’re losing fat and building lean tissue. Want to know what to really look out for? Check out these signs you're losing fat, not muscle to help stay on track.
When the weight won’t budge despite your best efforts, it’s tempting to think your body is broken. But often, lasting progress comes from shifting your approach. Choosing consistency and curiosity over extremes or all-or-nothing thinking.
Track what you eat and be honest about it
We tend to underestimate our intake. A few extra bites, dressings, drinks, or even ‘healthy’ snacks add up. Tracking (even for a week) can bring clarity, not for restriction, but for insight.
Prioritise whole, minimally processed foods
Not all calories are created equal. Highly processed foods can disrupt hunger and fullness signals, making it easy to overeat without realising it. Research shows that people eat significantly more when given ultra-processed foods, even when calories and macros are matched. Swapping out refined snacks for meals rich in fibre, protein, and water can help regulate appetite naturally.
Focus on building strength, not just burning calories
Instead of chasing sweat, build muscle. Resistance training helps preserve lean mass, supports metabolism, and improves insulin sensitivity, which are all critical for long-term fat loss. Even 2–3 short sessions a week can make a meaningful difference, especially if you’ve mostly done cardio in the past.
Sleep 7–9 hours (yes, it matters)
As mentioned, poor sleep messes with hunger hormones like ghrelin and leptin, increasing appetite and cravings, especially for high-calorie foods. Chronic sleep debt also makes it harder to regulate insulin, which disrupts how your body manages blood sugar and stores fat. If you’ve been skipping sleep to ‘fit in’ workouts or juggle tasks, reframe rest as a weight-loss ally, not an obstacle.
Manage stress in small, consistent ways
High cortisol (the stress hormone) can promote fat storage, particularly around the abdomen. But stress management doesn’t require a wellness retreat. Even 10 minutes of walking, deep breathing, or unplugging from devices can help regulate your nervous system and reduce emotional eating triggers.
Make small calorie adjustments if needed
If your weight has plateaued for a while, and you’ve accounted for sleep, stress, and movement, a slight calorie reduction (around 5–10%) may help. Just don’t make drastic cuts or skip meals that can backfire. Remember: sustainability > speed.
Talk to your GP or dietitian
Medical factors like hypothyroidism, PCOS, or certain medications can make weight loss more challenging. A blood test or medication review might offer answers. If you're on a GLP-1 or any weight management medication, nutrition and resistance training remain essential for preventing muscle loss and supporting long-term results.
If you’re tired of short-term fixes and frustrated by diets that don’t deliver lasting change, Interval Weight Loss offers a different path. One that’s backed by science, not just willpower.
Developed and tested by Dr Nick Fuller at the University of Sydney, this program uses a step-by-step approach to weight loss that’s designed to be sustainable. It helps reset your metabolism and supports a return to a healthy weight without triggering starvation mode.
It’s not a quick fix, and that’s the point. It's a long-term, sustainable approach that fits real life.
Wondering why nothing seems to work? The answer is rarely just about discipline. In reality, your body is wired to resist weight loss, not to sabotage you, but to protect you. The more extreme the approach, the harder it becomes to sustain.
Instead of doubling down on restriction, the key lies in consistency, muscle preservation, sleep, stress regulation, and eating in a way that works with your biology, not against it. Real progress isn’t always visible on the scale, and it certainly doesn’t happen overnight. But with a more informed, compassionate, and strategic approach, sustainable change is possible.
If nothing seems to work, don’t keep doing more of the same. Step back. Reassess. And if needed, work with a professional who can help tailor a plan to your physiology and needs, not just the latest trend.
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.