The hormones that control your metabolism (and what to do about them)

hormones insulin resistance metabolism weight loss Jul 03, 2026

When it comes to weight loss, we've all heard the mantra: eat less, move more. But if that really worked long-term, wouldn't we all be at our goal weight by now?

The truth is, your body isn't a simple calculator. It's a finely tuned, adaptive biological system, and at the heart of this system are hormones that regulate how you store, burn, and use energy. These aren't just "background chemicals." They're the bosses of your metabolism.

Here are the key hormones you need to understand for long-lasting weight loss and metabolic health, and how to support them through real food, smart meal timing, sleep, stress support, and gut care.

#1 Insulin: the master fat storage hormone

Insulin is made by your pancreas. Its main job is to move glucose (sugar) out of your blood and into your cells, either to be used for energy or stored for later.

When insulin is elevated, like after eating processed carbs or sugary snacks, your body switches into fat storage mode. It also blocks fat burning. Over time, consistently high insulin levels lead to insulin resistance, where your cells stop responding properly. This makes your body pump out even more insulin, leading to a vicious cycle of weight gain, especially around the belly.

One of the most overlooked drivers of chronically high insulin is grazing and snacking. If you eat throughout the day, a snack here, a bite there, insulin never has a chance to drop. And when insulin stays high, fat burning stays switched off.

✅ A low-carb real food approach, cutting back on snacks, and allowing proper gaps between meals helps lower insulin and supports better insulin sensitivity.

Read journal article here: Mechanisms of Insulin Resistance in Patients with Obesity

#2 Glucagon: insulin's fat-burning counterpart

Glucagon is also made by your pancreas, but by a different set of cells. Where insulin stores energy, glucagon releases it. When blood sugar drops between meals, glucagon signals your liver to release stored glucose and encourages your body to burn fat for fuel.

Insulin and glucagon are meant to work in a natural rhythm: insulin rises after eating, then falls; glucagon rises in the gaps, keeping blood sugar stable and fat burning active.

The problem is that when you're constantly eating or snacking, insulin stays elevated and glucagon is suppressed. This doesn't just slow fat burning, it actively blocks it. Many women who struggle to lose weight despite eating "not that much" are caught in this cycle: enough food to keep insulin high, but never low enough for glucagon to do its job.

✅ Eating real food at proper meals, with meaningful gaps in between and no grazing, gives glucagon the space it needs to work.

Read journal article here: Glucagon Control on Food Intake and Energy Balance

#3 Leptin: the 'I'm full' signal

Leptin is made by your fat cells. It sends a signal to your brain, particularly the hypothalamus, to say "we've got enough energy stored, you can stop eating now."

Sounds ideal, right? But here's the catch: when insulin is high and body fat increases, the brain becomes resistant to leptin's message. That's called leptin resistance, and it means even though your body has plenty of fat stored, your brain thinks you're starving. So you feel hungrier, store more fat, and crave high-calorie foods.

✅ To support leptin sensitivity, focus on whole meals rather than grazing, avoid ultra-processed snacks, and be cautious with extra fats between meals (like fat bombs or creamy coffees).

Read journal article here: The Leptin System and Diet: A Mini Review of the Current Evidence

#4 Ghrelin: the hunger hormone

Ghrelin is produced by the stomach and signals hunger to your brain. It rises before meals and falls after eating. But if you're sleep-deprived, chronically stressed, or eating at erratic times, ghrelin can stay elevated, making you feel hungry even when your body doesn't need food.

It also increases growth hormone and fat storage in certain conditions, especially when insulin is high.

✅ Consistent meal timing, seven to eight hours of quality sleep, and stress management techniques (like deep breathing or Tapping) help keep ghrelin in check.

Read journal article here: Ghrelin in the regulation of body weight and metabolism

#5 GLP-1 and GIP: the incretin hormones

GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) are both released from your gut in response to eating. Together, they stimulate insulin release after meals, slow digestion, and help regulate blood sugar.

GLP-1 also acts on your brain to reduce appetite and food cravings. GIP has a more complex role: in a healthy metabolic state, it supports appropriate insulin responses and helps regulate fat storage. In people with insulin resistance, however, GIP's ability to prompt insulin becomes blunted, and there is emerging evidence it may contribute to fat storage when the diet is high in refined carbohydrates.

This is why Mounjaro (tirzepatide) targets both GIP and GLP-1 receptors, combining their effects to produce stronger blood sugar control and greater appetite reduction than either pathway alone.

The good news is that your body can support these hormones naturally.

✅ Eating real, unprocessed meals, especially those rich in fibre and protein, supports healthy GLP-1 and GIP signalling. Constant snacking on ultra-processed foods, by contrast, overstimulates these pathways in ways that work against you over time.

Read journal article here: Satiety: a gut–brain relationship

#6 Peptide YY: the fullness signal from your gut

Peptide YY (PYY) is released from the lower small intestine and colon after eating. It signals fullness to your brain, slows digestion, and helps reduce appetite. Protein and fat are its strongest triggers, which is one of the reasons a protein-rich meal keeps you satisfied for longer.

People with obesity often have blunted PYY responses, meaning the "I'm done" signal is weaker, which makes it harder to stop eating before you've had too much.

Here's something worth knowing: PYY responds to complete, satisfying meals, not constant snacking. When you graze throughout the day, each small amount of food produces only a weak PYY signal. You never get that clear sense of fullness. This is one of the hormonal reasons why grazing tends to increase overall food intake rather than reduce it. It's not a lack of willpower. It's biology.

✅ Eating satisfying meals with adequate protein helps trigger a robust PYY response, making it genuinely easier to stop eating and stay comfortable between meals.

Read journal article here: Gut hormone PYY(3-36) physiologically inhibits food intake

#7 Cortisol: the stress hormone that messes with metabolism

Cortisol is released by your adrenal glands in response to stress, whether it's emotional stress, illness, poor sleep, or even under-eating. In short bursts, it helps your body respond to challenges. But when cortisol stays high for too long, it raises blood sugar, increases insulin resistance, and signals your body to store fat, especially around the middle.

It can also blunt the effects of other key metabolic hormones, including leptin and GLP-1.

✅ Sleep, gentle movement (like walking or yoga), time in nature, and practices like meditation or Tapping can lower cortisol and support better metabolic function.

Read journal article here: The Stress Axis in Obesity and Diabetes Mellitus: An Update

#8 Oestrogen: the midlife metabolic shift

Oestrogen is produced mainly by the ovaries, with smaller amounts made in fat tissue and the adrenal glands. It does far more than regulate the menstrual cycle. Oestrogen influences where your body stores fat, how sensitive your cells are to insulin, how well you sleep, and even how your brain regulates hunger and appetite.

In the years leading up to menopause, oestrogen levels begin to fluctuate and then decline. This is one of the key reasons many women notice a shift in their body during their forties and early fifties, even without changing their eating or exercise habits. Fat that previously settled on the hips and thighs tends to migrate towards the abdomen, where it is more metabolically active and more strongly linked to cardiovascular and metabolic risk.

Declining oestrogen also worsens insulin sensitivity, which means the same foods that didn't cause problems before can now trigger greater insulin spikes. It disrupts sleep (through night sweats and hot flushes), which in turn raises ghrelin and cortisol. And it affects the gut microbiome, specifically a group of bacteria called the estrobolome, which play a role in how oestrogen is metabolised and recycled in the body.

This is why the hormonal picture in midlife is not just about one hormone. Oestrogen, insulin, cortisol, and leptin are all talking to each other, and when oestrogen shifts, the whole system feels it.

✅ You can't stop the natural decline in oestrogen, but you can support the system around it. Real food, gut health, quality sleep, and stress management all help maintain insulin sensitivity and reduce the metabolic impact of changing oestrogen levels. Resistance exercise also helps preserve lean muscle mass, which supports metabolism as oestrogen declines.

Read journal article here: The importance of estradiol for body weight regulation in women

What you can do to support your hormones

Your hormones aren't set in stone. They're dynamic, and you can influence them every day through the choices you make.

Here are some of the most powerful tools:

Low-carb real food: Reduces insulin spikes, supports leptin, GLP-1, GIP, and PYY, and helps regulate ghrelin.
Eating proper meals, not grazing: Three satisfying meals a day, without snacking between them, allows insulin to drop, glucagon to rise, and fat burning to occur. It also supports a stronger PYY satiety signal, so stopping eating becomes easier, not harder.
Sleep: Supports the natural rhythms of ghrelin and leptin, and helps keep cortisol in check.
Stress management: Lowers cortisol, supports insulin sensitivity, and improves your body's ability to burn fat rather than store it.
Gut health: A thriving microbiome improves insulin sensitivity, lowers inflammation, supports GLP-1 and PYY production, and even plays a role in mood and motivation.
Resistance exercise: Helps preserve lean muscle mass and supports metabolic rate, particularly important as oestrogen declines in midlife.

But the real key to lasting change?

👉 Mindset.

Because knowing all of this is one thing, but implementing it in your real, everyday life (with work, kids, family demands, and hormones!) is another.

That's where support, strategy, and self-compassion come in. Your mindset is the bridge between knowing what works and actually doing it consistently in a way that feels realistic, sustainable, and empowering.

My Metabolic Action Plan

If reading this has made you think "I understand this, but where do I actually start?", that's exactly why we created My Metabolic Action Plan (My MAP). My MAP brings these hormonal strategies together in a clear, structured programme that works in your real life, not an ideal one. You'll learn how to eat in a way that supports your metabolism, develop the mindset skills that make change stick, and get the practical tools to implement it all without feeling overwhelmed. It's not about being perfect. It's about understanding how your body works and finally having a path that makes sense.

Find out more about My Metabolic Action Plan

Take-home points

It's not just about calories. It's about how your hormones are working.
Chronically high insulin, driven in part by constant snacking and grazing, is one of the root causes of modern weight gain.
Insulin, glucagon, leptin, ghrelin, GLP-1, GIP, peptide YY, cortisol, and oestrogen all play a role in hunger, energy, cravings, and fat storage.
The hormonal shifts of perimenopause and menopause are real, and they change how your body responds to food, stress, and sleep.
You can influence these hormones through food choices, meal timing, sleep, stress care, gut health, and resistance exercise.
Mindset is what makes all of it sustainable.

You have the power to shift these hormones, not through willpower, but through understanding how your body works and giving it what it actually needs.

Dr Mary Barson and Dr Lucy are the founders of Real Life Medicine. They help women who have been on every diet under the sun, optimise their health and achieve long lasting weight loss without feeling miserable or deprived.

They do this with their 3 step framework that

Improves metabolism
Develops mindset skills
Provides tools to implement it easily into busy lives

With this comes increased energy, vitality and confidence.

You can avoid chronic disease and stop living life on the sidelines!

Check out My Metabolic Action Plan