Why is it so hard to lose weight? What is metabolic adaptation? (Part 1/2)

April 9, 2025

8 Min Read

Written By:

Kylie Russell and Dr Peter Carr-Boyd

Ever wondered why you can lose weight to a point, but then it all goes back on, and then some?😩 If so, you need to understand ‘metabolic adaptation’. And to do this, we’re going to need to take a quick review of the science.

Let's get our nerd on and dive into some science to understand why losing weight is more complex than just cutting calories. The first law of thermodynamics tells us that energy in a closed system can’t be created or destroyed, only transformed from one form to another. This principle is often cited by proponents of the calories in/calories out theory, suggesting that reducing calorie intake should directly lead to weight loss. However, the human body isn't a simple closed system. While we do consume and expend energy, our bodies also store it, and this storage mechanism—along with metabolic adaptation—complicates weight management.

Consider how our bodies store energy. After consuming food, once glycogen stores are replenished (glycogen being a readily available energy source that can be quickly converted to glucose), excess energy is stored as fat. This is an evolutionary adaptation designed to help us survive during periods of food scarcity. Unfortunately, this efficient fat storage means that if we don’t use these reserves, over time, they can lead to weight gain.

Many diets claim that adhering to the principle of reducing energy intake through various strategies—like calorie counting, portion control, or intermittent fasting, will lead to sustainable weight loss. So ofcourse it's natural to think that cutting back on calories would prompt the body to burn stored fat for energy, leading to weight loss. The reality is more complicated as we all know. You might have tried several of these methods and seen some initial success, but what often happens?

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Why does the weight go back on?

When we restrict our energy intake, a series of homeostatic and metabolic adaptations begin including changes in mitochondrial efficiency (the body’s energy power stations)², and alterations in the levels of circulating hormones¹. These are designed to prevent the body from shedding all its energy stores. Remember, from an evolutionary sense, we need to be ready for the next famine so we try very hard to hang on to energy. This is called metabolic adaptation and refers to the body's way of adjusting its energy expenditure in response to reduced calorie intake and weight loss.

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So what happens when we try to lose weight?

Your body slows down its Resting Metabolic Rate (RMR) which is the amount of energy the your body expends at rest to maintain basic physiological functions like breathing, circulation and cell production.
Your body increases its energy efficiency, meaning it requires fewer calories to perform the same activities. Would be great if your car did this, but not great if you’re trying to lose weight.
The level of certain hormones that regulate hunger and energy expenditure in your body change. For example, Leptin levels drop which increases your appetite, while ghrelin levels rise, which stimulate hunger. That’s right, we get more hungry!

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The extent of these changes depends on several factors.

1. The length of the caloric-restriction period, with longer durations leading to greater adaptations.

2. The size of the energy deficit, with larger deficits triggering more substantial homeostatic responses.

3. The initial body composition, with lower body fat levels before the intervention causing more pronounced metabolic adaptations^3,4..

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But why does the body do this? Isn’t weight loss a good thing if I’m living with excess weight?

To answer the second question first, absolutely it is! Especially in today's society with such high rates of overweight and obesity. We know that if we have excess weight, even small to moderate amounts of weight loss can improve our health. For example, 5% to 10% weight loss is associated with improvement in glycaemic control, systolic and diastolic blood pressure and cholesterol profiles. If you lose 10% to 15%, this can result in improvements in sleep apnoea and non-alcoholic steatotic hepatitis (NASH)⁵. If you are overweight or obese and you lose more than 15% of your weight, the benefits can be greater again. There is evidence to say you are likely to even live longer! But the point is, any improvement towards a healthy weight is fantastic for our health.

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Now, to answer the first question: Why does the body do this? And why does the body not want to be in a healthy weight range and resist weight loss? The answer is due to our evolutionary past. Not surprising, natural selection favoured those who survived famines, and over thousands of years, this shaped our genetic make-up⁶. That’s right, our genes control our weight a lot! In today's environment with food-a-plenty, this once beneficial trait now contributes to weight gain. Simply put, our ancient saviour has become our modern issue. Another reason lies within the brain region called the "hypothalamic feeding centre”. This area of the brain has direct line communication with our organs and regulates food intake^7,8. The hypothalamus in our brain receives signals from hormones (like leptin, ghrelin, and insulin) from the gut and adipose tissue, in addition to neural input from the vagus nerve. It uses this information to establish an energy reserve set-point and also a “weight” set point. This energy reserve is mainly in adipose tissue with some as glycogen^9,10. When there is variation away from the set-point, most pronounced when energy stores go down, the hypothalamus directs our behaviour, often in the form of seeking more food. You may be thinking then why does this system allow weight to be gained if it’s unhealthy? The hypothalamus is less concerned with excess energy: for thousands of years of human evolution, it never really had to. It eventually adjusts the set point ‘up’ and the body then defends a higher weight.

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What hope is there then for me to lose weight and keep it off?

Don’t panic. Although we now understand that we are fighting against our own biology to lose weight, there are nutritional and exercise strategies that can be used to address these adaptations to body mass loss. Check out our blog here (hyperlink to ‘Strategies to tackle metabolic adaptation’).

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This said, we need to be realistic about how much weight loss we can achieve on our own. The LOOK AHEAD study is the largest study looking at lifestyle interventions for weight loss in patients with diabetes (11). Whilst weight loss was 8.6% at one year, this was only 4.7% at 8 years. At rfynd, we recommend a great place to start is our Essentials program (hyperlink to this webpage), where you receive dietitian advice, regular coaching support, and access to 4000+ exercises through our partners at Centr. But if you’ve already had a couple of serious weight loss attempts using these supports, you may want to consider complementary therapies such as weight loss medications or surgery (link to webpages). Check out our other blogs to see if these might be right for you. Also, feel free to complete the quiz today to see if you qualify (CTA quiz).

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By Kylie Russell, Dietitian and Dr Peter Carr-Boyd, Surgeon

References:

Rosenbaum, M., Leibel, R. Adaptive thermogenesis in humans. Int J Obes 34 (Suppl 1), S47–S55 (2010). https://doi.org/10.1038/ijo.2010.184
Bevilacqua, L., Ramsey, J. J., Hagopian, K., Weindruch, R., & Harper, M. E. (2004). Effects of short-and medium-term calorie restriction on muscle mitochondrial proton leak and reactive oxygen species production. American Journal of Physiology-Endocrinology and Metabolism, 286(5), E852-E861.
Peos, J. J., Norton, L. E., Helms, E. R., Galpin, A. J., & Fournier, P. (2019). Intermittent dieting: theoretical considerations for the athlete. Sports, 7(1), 22.
Trexler, E. T., Smith-Ryan, A. E., & Norton, L. E. (2014). Metabolic adaptation to weight loss: implications for the athlete. Journal of the International Society of Sports Nutrition, 11, 1-7.
Ryan, D. H., & Yockey, S. R. (2017). Weight loss and improvement in comorbidity: differences at 5%, 10%, 15%, and over. Current obesity reports, 6, 187-194.
O'Rourke, R. W. (2014). Metabolic thrift and the genetic basis of human obesity. Annals of surgery, 259(4), 642-648.
Cowley, M. A., Pronchuk, N., Fan, W., Dinulescu, D. M., Colmers, W. F., & Cone, R. D. (1999). Integration of NPY, AGRP, and melanocortin signals in the hypothalamic paraventricular nucleus: evidence of a cellular basis for the adipostat. Neuron, 24(1), 155-163.
Schwartz, M. W., Seeley, R. J., Zeltser, L. M., Drewnowski, A., Ravussin, E., Redman, L. M., & Leibel, R. L. (2017). Obesity pathogenesis: an endocrine society scientific statement. Endocrine reviews, 38(4), 267-296.
Kennedy, G. C. (1953). The role of depot fat in the hypothalamic control of food intake in the rat. Proceedings of the Royal Society of London. Series B-Biological Sciences, 140(901), 578-592.
Konturek, S. J., Konturek, P. C., Pawlik, T., & Brzozowski, T. (2004). Brain-gut axis and its role in the control of food intake. Journal of physiology and pharmacology, 55(2), 137-154.
Wadden, T.A., Bantle, J.P., Blackburn, G.L., Bolin, P., Brancati, F.L., Bray, G.A. and Grp, L.A.R., 2014. Eight-year weight losses with an intensive lifestyle intervention: The look AHEAD study. Obesity, 22 (1), 5–13.

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July 9, 2025

Can GLP-1s Like Wegovy Help Fatty Liver Disease?

Fatty liver disease, particularly non-alcoholic fatty liver disease (NAFLD) and its more severe form, non-alcoholic steatohepatitis (NASH)—is now one of the most common liver conditions globally. Affecting up to 1 in 3 adults in New Zealand, it’s closely linked to overweight and obesity, type 2 diabetes, and insulin resistance.

But there’s promising news: GLP-1 receptor agonists, such as Wegovy (semaglutide), originally developed for diabetes and weight loss, are now showing powerful benefits for people with fatty liver disease.

Let’s look at how they work and what the latest research says.

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What Is NAFLD and Why Does It Matter?

NAFLD occurs when excess fat builds up in liver cells, not caused by alcohol. Over time, this fat can lead to inflammation (NASH), fibrosis (scarring), cirrhosis, and even liver cancer.

Unfortunately this a silent epidemic—often with no symptoms until the damage is severe.

Risk factors include:

Obesity
Insulin resistance
Type 2 diabetes
High cholesterol and triglycerides

There is currently no approved medication specifically for NAFLD or NASH. The mainstay of treatment has been lifestyle changes like weight loss and exercise. But maintaining long-term weight loss can be incredibly challenging.

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Enter: GLP-1 Receptor Agonists

GLP-1s (glucagon-like peptide-1 receptor agonists) are medications that:

Improve insulin sensitivity
Slow gastric emptying
Reduce appetite
Lead to substantial weight loss

Wegovy (semaglutide) is one of the most potent GLP-1s, approved for chronic weight management in New Zealand. But its benefits extend beyond weight loss.

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What the Research Says: GLP-1s and Liver Health

Here are some key studies and findings that show how GLP-1s can improve fatty liver disease:

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1. Semaglutide Improves NASH Histology

In a randomised controlled trial published in The New England Journal of Medicine (2021), researchers gave semaglutide to patients with biopsy-proven NASH.

✅ 59% of patients had NASH resolution with no worsening of fibrosis—compared to just 17% on placebo.

📖 Reference: Newsome PN et al. (NEJM, 2021) [1].

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2. Weight Loss Drives Liver Fat Reduction

GLP-1s induce 10–15% total body weight loss in many patients.

Even a 5–10% weight reduction is enough to significantly improve liver fat, inflammation, and fibrosis [2].

Semaglutide helps people reach these targets more reliably than diet and exercise alone.

📖 Reference: Armstrong MJ et al., The Lancet, 2016 [2].

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3. Reduces Liver Fat on Imaging

A 2020 study in The Lancet Gastroenterology & Hepatology found that semaglutide significantly reduced liver fat content on MRI-based imaging, even in non-diabetic individuals with NAFLD.

📖 Reference: Flint A et al., Lancet Gastroenterol Hepatol, 2020 [3].

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4. Improves Cardiometabolic Risk Factors

GLP-1s don’t just help the liver—they also improve:

Blood sugar control
Blood pressure
Lipids (LDL, triglycerides)

These improvements reduce the overall cardiovascular risk in people with NAFLD, which is a leading cause of death in this population.

📖 Reference: Marso SP et al., NEJM, 2016 (LEADER trial) [4].

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5. Promising Real-World Data

Recent real-world cohort studies have shown that people with NAFLD on GLP-1 therapy experience reductions in liver enzymes (ALT, AST), indicating better liver function over time.

📖 Reference: Newsome PN et al., J Hepatol, 2021 [5].

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Are GLP-1s Right for You?

If you have fatty liver disease GLP-1s like Wegovy could offer a dual benefit:

✔️ Sustained weight loss

✔️ Improvement in liver health

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At rfynd, we offer a medically supported GLP-1 weight loss program that includes:

Prescription access (Wegovy, Saxenda, or similar)
Specialist clinician support
Nutrition and lifestyle coaching
Optional liver health monitoring

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Final Thoughts to consider

Fatty liver disease is more common—and more serious—than many people realise. Fortunately, science is catching up. GLP-1 medications like Wegovy are emerging as powerful tools, not just for weight loss but for protecting your liver and reducing long-term health risks.

Want to explore if Wegovy is right for your liver health journey?

👉 Book a consultation with one of ou r rfynd medical team today

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What About Bariatric Surgery for Fatty Liver Disease?

While medications like Wegovy are powerful tools for weight loss and liver health, for some people—particularly those with a BMI >30 —metabolic (bariatric) surgery may offer the most dramatic and lasting improvement in fatty liver disease.

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Here’s what the evidence shows:

1. High Rates of NASH Resolution and Fibrosis Improvemen

In one of the largest long-term studies published in Gastroenterology (2015), researchers followed 180 patients with biopsy-proven NASH who underwent bariatric surgery.

✔️ 85% achieved NASH resolution

✔️ 34% had fibrosis regression

📖 Reference: Lassailly G et al., Gastroenterology, 2015 [6].

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2. Massive Reductions in Liver Fat and Inflammation

A meta-analysis published in Obesity Surgery (2020) reviewed 32 studies and found bariatric surgery resulted in:

91.6% reduction in steatosis
81.3% resolution of NASH
65.5% improvement in fibrosis

📖 Reference: Lee Y et al., Obes Surg, 2020 [7].

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3. Liver Function Markers Improve Quickly

Within 6–12 months of surgery, liver enzymes (ALT, AST) typically fall to normal or near-normal levels. Improvements often occur before full weight loss is achieved, suggesting mechanisms beyond just fat loss—such as improved insulin sensitivity and gut hormone regulation.📖 Reference: Mathurin P et al., Journal of Hepatology, 2009 [8].

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‍4. Lowers Risk of Cirrhosis and Liver-Related Death

A large retrospective study from JAMA (2021) showed that bariatric surgery in patients with obesity and NAFLD was associated with:

48% reduced risk of developing advanced liver disease
70% reduction in liver-related mortality

📖 Reference: Aminian A et al., JAMA, 2021 [9].

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5. Reduces Overall Cardiometabolic Risk and Mortality

Since NAFLD is a multi-system disease, patients benefit not only from improved liver health but also:

Better blood sugar control
Improved lipid profile
Lower cardiovascular risk and cancer risk

📖 Reference: Sjöström L et al., New England Journal of Medicine, 2007 [10].

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Surgery vs. Medication: Complementary Options

While GLP-1s and bariatric surgery both improve fatty liver disease, the choice depends on the individual:

GLP-1s are ideal for those seeking non-invasive therapy or who aren’t surgical candidates.
Bariatric surgery offers a more pronounced and durable option—especially for those with a BMI>30.

At rfynd, we work with you to explore both options, offering:

GLP-1 medical weight loss programs
Bariatric surgery with trusted surgeons
Ongoing liver monitoring and health coaching

Want to explore if bariatric surgery is right for your liver health journey?

👉 Book a consultation with one of our rfynd surgeons today.

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July 9, 2025

How Effective Is Wegovy®? What the STEP Trials Say About Real Weight Loss

Whats the hype?

If you’ve struggled with dieting, calorie counting, gym memberships, or trendy detoxes that promise the world but deliver disappointment — you’re not alone. At rfynd Weight Loss, we work with people like you every day who’ve “done all the right things” and still feel stuck.

Wegovy® (semaglutide) has sparked major interest — not just from celebrities or social media, but from serious clinical research. The STEP trials (Semaglutide Treatment Effect in People with obesity) offer clear, trustworthy evidence behind how well Wegovy works, who it helps, and what results you can expect.

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Here’s a breakdown of the STEP 1–5 clinical trials

🧪 What Are the STEP Trials?

The STEP Trials includes five large, global clinical trials that tested Wegovy’s effect on weight loss (compare to placebo) in people with obesity or overweight. These trials involved thousands of real people — like you — looking for lasting solutions. Most had tried and failed with diet and exercise alone. By the way, “placebo’s” are treatments with no active ingredients.

STEP 1: Wegovy vs. Placebo (and no diabetes)

📊 Participants: 1,961 adults with obesity or overweight
⏱ Duration: 68 weeks
💊 Treatment: Wegovy 2.4 mg weekly vs placebo, both with lifestyle advice

✅ Results:

Average 14.9% weight loss with Wegovy vs 2.4% with placebo
Over 1 in 3 people lost more than 20% of their body weight

👩‍⚕️ What this means for you:
Most participants were women in their 40s and 50s, but men were also included. This is the gold-standard trial showing that Wegovy helps people finally lose real, significant weight, even after many failed attempts.

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STEP 2: Wegovy in people with Type 2 Diabetes

📊 Participants: 1,210 adults with obesity/overweight + type 2 diabetes
⏱ Duration: 68 weeks
💊 Treatment: Wegovy 2.4 mg vs semaglutide 1 mg vs placebo

✅ Results:

Average weight loss was 9.6% with Wegovy vs 3.4% with placebo
Improvements in HbA1c and blood sugar control

👩‍⚕️ What this means for you:
Even if you have type 2 diabetes (a common condition in those with obesity), Wegovy still offers meaningful weight loss and improves blood sugar. Results are slightly less than STEP 1 due to insulin-related effects, but still impressive.

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STEP 3: Wegovy + Intensive Lifestyle Support

📊 Participants: 611 adults with obesity
⏱ Duration: 68 weeks
💊 Treatment: Wegovy 2.4 mg + intensive behaviour therapy vs placebo + therapy

✅ Results:

Wegovy group lost 16% of body weight vs 5.7% in placebo
Faster weight loss with early improvements in mood and energy reported

👩‍⚕️ What this means for you:
When Wegovy is combined with personalised coaching and support results are even better. This trial shows how mindset, movement, and medication work together. This is another reason why rfynd has built a team of support around you.

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STEP 4: What Happens If You Stop Wegovy?

📊 Participants: 902 adults who lost weight on Wegovy
⏱ Duration: 48 weeks (after initial 20-week run-in)

✅ Results:

Those who stayed on Wegovy maintained their weight loss
Those who stopped gained back ~6.9% of their weight

👩‍⚕️ What this means for you:
Wegovy isn’t a quick fix — it's a long-term tool. But with the right support, you can maintain your results. Think of it as a foundation, not a forever dependency.

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STEP 5: Long-Term Wegovy Use – Over 2 Years

📊 Participants: 304 adults
⏱ Duration: 2 years
✅ Results:

15.2% average weight loss over 104 weeks
Most weight lost in the first year, maintained in year two

👩‍⚕️ What this means for you:
Long-term weight loss is possible and sustainable. This is key is you’re looking for lasting change, not yo-yo diets.

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❤️ Final Thoughts

The STEP trials clearly show that Wegovy is more than hype — it’s a clinically proven tool for meaningful, sustained weight loss. And for those of you who’ve spent years trying and failing with typical diets, this can feel like a breath of fresh air.

But weight loss isn’t just about medication. At rfynd Weight Loss, we blend expert care, mindset coaching, and nutrition planning into a personalised, shame-free program tailored for you.

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👉 What’s Next?

📖 Read this next:
Understanding Wegovy® Side Effects – So you know what to expect before you begin

📖 Or check out:
Strategies to Manage Side Effects of Wegovy® – For practical, easy-to-follow tips to stay on track

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July 9, 2025

Strategies to Manage Side Effects of Wegovy®

Written By:

Kylie Russell and Dr Peter Carr-Boyd

8 Min Read

Read Now

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The rfynd Programs are overseen by a team including medical specialists, dietitians, health psychologists and nurses.  Under New Zealand regulations, these professionals are unable to use reviews or testimonials to advertise their services.

If you have any questions about our services and how they might benefit you, we'd love to talk.

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Why is it so hard to lose weight? What is metabolic adaptation? (Part 1/2)

References:

Reading More

Can GLP-1s Like Wegovy Help Fatty Liver Disease?

How Effective Is Wegovy®? What the STEP Trials Say About Real Weight Loss

Strategies to Manage Side Effects of Wegovy®

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Why Am I Not Seeing Any Testimonials Or Reviews Here?

Weight care, your way.

Quick Links