Ask the Expert: Endocrinology – It’s Not Willpower, It’s Biology

Sometimes losing weight can feel like fighting a losing battle. If you’ve tried eating less and moving more, but still find yourself stuck at the same weight (or regaining weight you’ve lost), it’s easy to feel like there’s something wrong with you.

But what if there was a biological reason that you can’t seem to succeed on healthy eating plans?

In this Ask the Expert episode, Simple Online Pharmacy’s Superintendent Pharmacist Aamina Rafiq sat down with consultant endocrinologist Dr Andrew Kernohan from Weight Loss Medics. She got the answers to the most common questions on the biological factors that most weight loss advice ignores.

They discuss how hormones play a role in appetite regulation, the science behind GLP-1 weight loss treatments, how cortisol can influence food choices, how “food noise” differs from physical hunger, and much more.

What is Endocrinology?

Endocrinology is the study of hormones. It is a branch of medicine that looks at the body’s endocrine system: hormones and the glands that produce them (e.g. your adrenal glands, pituitary glands and thyroid glands).

Hormones carry messages between cells, and are responsible for important functions like metabolism, sleep, blood sugar levels, hunger, stress levels and body temperature.

But some people’s hormone levels may become unbalanced – your body might be producing too much or too little of certain hormones.

Why Would You See an Endocrinologist?

You may see an endocrinologist if you’re experiencing a condition caused by a hormone imbalance or if your glands are either too big or too small. Common endocrine disorders include thyroid disorders, type 1 diabetes, type 2 diabetes and PCOS.

An endocrinologist can check everything is working as it should be.

Will an Endocrinologist Help With Weight Loss?

Yes, endocrinologists can help with weight loss. They can support you by:

• Treating and managing underlying conditions that may cause weight gain
• Treating and managing the medical conditions linked to or caused by obesity
• Helping you stay on track and manage side effects on GLP-1 weight loss treatment

What Are the Signs of a Hormone Imbalance?

Unexplained weight loss can be a sign of a hormone imbalance.

Signs of an underactive thyroid include:

• Unexplained weight gain
• Feeling cold all the time

You could be producing too much cortisol (AKA the “stress hormone”) if you’re experiencing:

• Unexplained weight gain
• Easy bruising
• High blood pressure
• Muscle weakness
• Stretchmarks

What Symptoms Should You Never Ignore?

If you’re gaining weight and not sure why, don’t ignore the following symptoms:

• Excessive thirst: This could be a sign that you’re developing diabetes. It’s common if you have obesity.
• Anxiety, palpitations and tremor: This could signal an overactive thyroid.

There are many other medical conditions that can be serious and may be associated with unexplained weight loss.

How Does the Body Decide When We Feel Hungry vs Full?

Your body produces two hormones that play a big role in regulating satiety and hunger:

• Leptin (the satiety hormone). It’s produced in the fat cells and tells your brain you’ve had enough food.
• Ghrelin (the hunger hormone). It tells your brain you’re hungry and stimulates your appetite.

When you eat, your body releases these hormones from the gut to balance appetite and your food intake.

What Hormones Play a Role in Appetite Regulation?

As well as leptin and ghrelin, other hormones that regulate appetite include:

• Glucagon-like peptide-1 (GLP-1)
• Glucose-dependent insulinotropic polypeptide (GIP)
• Cholecystokinin (CKK)
• Peptide YY (PYY)

What’s the Difference Between Food Noise and Physical Hunger?

“Food noise” is a relatively new term used to describe thoughts around food, like what you’re eating, how much you’re eating and when.

It’s not the same as true hunger. Physical hunger is driven by ghrelin, the hunger hormone.

How Does Chronic Dieting Affect Hormonal Hunger Signals Over Time?

Chronic dieting and yo-yo dieting can negatively impact your health.

In fact, Dr Kernohan says research has shown that hunger hormones can become unregulated in chronic or serial dieters. This can lead to the satiety hormone not working as well, so you may feel hungrier and less satisfied after eating.

Why Is Obesity Now Considered a Metabolic Condition?

According to Dr Kernohan, it’s because we now have a better understanding of obesity and the role that hormones play in influencing our food choices.

The introduction of better treatments has also shifted this perception. In one case, a patient only realised she had biological problems after using GLP-1s.

How Do Stress Hormones Like Cortisol Affect Appetite?

Too much cortisol can cause weight gain, among other health problems.

There are some diseases related to cortisol that are rare, such as Cushing’s disease.

However, people react to stress differently. According to recent research, people who produce higher levels of cortisol in response to stressors tend to choose higher-calorie comfort foods more often.

Can Chronic Stress Reduce the Effectiveness of Weight Loss Treatment?

Yes. Cortisol influences food choices. It can also cause the body to hold onto fat and calories. Cortisol may also influence how well you stick to habits and make lifestyle changes.

Is Stress Management Key For Weight Loss?

Yes, stress management is important. Adopting a “mindful” approach to eating can help people choose healthier foods.

However, it’s uncertain as to whether mindfulness alone is enough for some people who struggle with their weight.

How Do GLP-1s Impact Muscle and Bone Health?

Muscle loss is a problem for anyone who loses a significant amount of weight. If you’ve lost a lot of weight, 25% or more could be muscle, Dr Kernohan says. This is true whether you’ve lost weight using GLP-1s, after bariatric surgery or through dietary changes.

But there are ways to reduce muscle loss as you lose weight. You can do this by adding a high-protein diet, which can increase satiety and mitigate muscle loss. Adding resistance exercises to your routine can also help to maintain muscle mass.

Looking after your bone health on your weight loss journey is also important, particularly if you’re going through menopause or perimenopause. Weight loss can increase bone turnover, so you might experience bone loss faster.

You can avoid bone loss by losing weight slowly and steadily, and avoiding rapid weight loss. Exercise can also help you avoid bone loss.

Can You Increase GLP-1 Release Naturally?

GLP-1 is a hormone your body naturally produces in cells of your small bowel. Your body releases GLP-1 into the bloodstream when nutrient-dense food reaches the bowel.

Some foods might be better at releasing GLP-1 than others. This includes fibre-rich foods (like fruit and veg) and protein-rich foods. Dr Kernohan says research cited avocados in particular as being effective at releasing GLP-1.

Should Obesity Be Treated as a Chronic Condition Requiring Long-Term Therapy?

Obesity is a long-term problem that a lot of people struggle with. Some patients who use GLP-1 treatments do regain a significant amount of weight back when they stop. So some patients will need long-term treatment to avoid that.

However, Dr Kernohan says around 1 in 5 people manage to maintain their weight after they stop GLP-1 treatment. Healthy lifestyle habits, like diet and exercise are key for achieving this.

Key Takeaways

• Weight struggles are not always about willpower: Hormones and metabolism can strongly influence hunger, fullness, and food choices.
• Leptin and ghrelin help regulate satiety and appetite: Repeated dieting can disrupt these signals over time.
• “Food noise” vs hunger: Food noise is different from physical hunger and may be linked to biological drivers, not simply habits.
• How stress plays a role: Cortisol can increase appetite and preference for higher-calorie comfort foods, and may make it harder to stick to healthy routines.
• Significant weight loss can reduce muscle and affect bone health: Prioritising protein, resistance exercise, and steady weight loss can help protect both.

References

Newman, E., O’Connor, D.B. and Conner, M. (2007). Daily hassles and eating behaviour: The role of cortisol reactivity status. Psychoneuroendocrinology, 32(2), pp.125–132. doi: https://doi.org/10.1016/j.psyneuen.2006.11.006 [Accessed 30 Jan. 2026].

Europe PMC (2016). Europe PMC. [online] Europepmc.org. Available at: https://europepmc.org/article/MED/22029981 [Accessed 30 Jan. 2026].

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