GLP-1 Medications, Retatrutide & Metabolic Health: What You Need to Know

Ozempic®. Wegovy®. Mounjaro®. Zepbound®. And now, Retatrutide.

Unless you have been living under a rock, you have probably heard a lot about GLP-1 medications.

They have completely changed the conversation around weight loss, diabetes, appetite, and metabolic health. Now, with newer medications targeting multiple hormone pathways at once, that conversation is evolving even more quickly.

IMPORTANT... here is the part I don't want us to lose:

Weight loss and metabolic health are not exactly the same thing.

These medications can be incredibly effective tools for the right person. Whether you are taking a GLP-1 medication, considering one, or choosing not to use medication at all, what you eat, how you move, how well you preserve muscle, and the habits you build still matter. A LOT!!

So let's break down what GLP-1 actually is, how these medications work, what makes Retatrutide different, and, most importantly, where nutrition fits into the picture.

First, What Exactly Is GLP-1?
GLP-1 stands for glucagon-like peptide-1, a hormone naturally released by your gut after you eat. Think of it as one of the messengers that helps coordinate what happens after food enters your system.

GLP-1 helps stimulate insulin release, meaning it signals your pancreas to release insulin when blood sugar rises so glucose can move out of your bloodstream and into your cells to be used for energy.

At the same time, it helps reduce glucagon secretion. Glucagon is a hormone that tells your liver to release stored glucose into your bloodstream. When you have just eaten and glucose is already available, GLP-1 helps quiet that signal so your liver isn't adding unnecessary glucose to the mix.

GLP-1 also slows gastric emptying, which simply means food leaves your stomach and moves into your small intestine more slowly. This can help you feel satisfied longer after eating and can also slow how quickly glucose enters your bloodstream.

Finally, GLP-1 communicates with areas of your brain involved in appetite and satiety, your body's sense of fullness and satisfaction after eating. This signaling can help decrease hunger and reduce the desire to continue eating.

So, in simple terms, GLP-1 helps coordinate blood sugar, digestion, hunger, and fullness after you eat, which explains why this one hormone has become such an important target in medications used to treat diabetes and obesity.

However, GLP-1 isn't working alone. Your metabolism involves constant communication between your gut, brain, pancreas, liver, muscle, adipose tissue, and multiple hormones. This is one reason I think we have oversimplified weight management for far too long.

It's not simply a matter of eating less and moving more.

Nor is it simply about willpower.

Not All “GLP-1 Medications” Are the Same
We tend to throw all of these medications into one big “GLP-1” bucket, but they don't all work the same way. The biggest difference is which hormone receptors they target.

Think of a receptor as a tiny receiving station on a cell. Hormones normally bind to these receptors and deliver specific messages. A receptor agonist is a medication that activates a receptor and mimics or enhances the effects of the hormone that would normally communicate with it.

Semaglutide, the active medication in Ozempic® and Wegovy®, is a GLP-1 receptor agonist. It activates the GLP-1 receptor, helping enhance the same pathways we just talked about: blood sugar regulation, slower gastric emptying, increased satiety, and reduced appetite.

Tirzepatide, the active medication in Mounjaro® and Zepbound®, is a dual GIP/GLP-1 receptor agonist, meaning it targets two hormone pathways instead of one.

GIP stands for glucose-dependent insulinotropic polypeptide (no, there won’t be a test at the end of this!!). Like GLP-1, GIP is an incretin hormone, a gut hormone released in response to eating that helps your body manage the nutrients coming in.

GIP helps stimulate insulin secretion when glucose is elevated and is also involved in metabolic signaling related to appetite, fat tissue, and energy balance.

So, in very simple terms:

Semaglutide → targets one receptor: GLP-1
Tirzepatide → targets two receptors: GIP + GLP-1

Researchers have now taken that concept one step further by developing a medication that targets three receptors at the same time.

Introducing… Retatrutide.

You have probably started hearing about Retatrutide, and I suspect we are going to be hearing A LOT more about it.

Retatrutide is an investigational medication developed by Eli Lilly that targets three hormone receptors simultaneously: GIP, GLP-1, and glucagon. This is why it's referred to as a triple hormone receptor agonist.

You may also see people on social media calling Retatrutide a “GLP-3.” This is catchy, but it's not scientifically accurate. There isn't a new hormone called GLP-3. Retatrutide simply targets three different hormone pathways, and the research is getting a lot of attention for good reason.

In the Phase 3 TRIUMPH-1 trial involving adults with obesity without diabetes, Retatrutide produced substantial average weight reductions over 80 weeks. At the 12 mg dose, the mean reduction was approximately 25% of initial body weight using the treatment-regimen analysis. Other analyses evaluating participants while adhering to treatment have reported even greater reductions.

Those are impressive numbers.

But, and this is an important BUT, as of October 2026, Retatrutide is still investigational and is NOT FDA-approved.

It is currently being studied in Phase 3 clinical trials for obesity, type 2 diabetes, and several obesity-related conditions.

That also means something else that is really important to understand. If you see Retatrutide being sold online right now, you are not purchasing an FDA-approved version of the medication. The FDA has specifically warned consumers about unapproved Retatrutide products and has stated that Retatrutide cannot currently be used in compounding under federal law.

So yes, the research is very promising, but no, this is not yet a medication that your doctor can prescribe as an FDA-approved treatment.

So Where Does Nutrition Fit Into All of This?
This is where I think we need to change the conversation.

For years, we have treated medication and lifestyle as though they are competing approaches.

Medication OR nutrition.
Medication OR exercise.
Medication OR “doing it naturally.”

Why?

For many people, the better question is: How can we use every appropriate tool available while protecting muscle, supporting the gut, meeting nutritional needs, improving metabolic health, and building habits that can actually be sustained?

Taking medication does not make nutrition irrelevant.

In fact, when a medication significantly decreases your appetite and food intake, I would argue that nutrition becomes even more important (SHOCKER!!!!).

If you are eating considerably less food, we need to make sure the food you ARE eating is actually nourishing you, and one of my biggest concerns is muscle.

Let's Talk About Muscle
One of the biggest misconceptions surrounding GLP-1 medications is that every pound lost is body fat. Unfortunately, that is not how weight loss works.

When someone loses a significant amount of weight, whether through medication, bariatric surgery, calorie restriction, or another method, some lean mass is typically lost along with body fat.

Body-composition studies involving medications such as semaglutide and tirzepatide have shown reductions in both fat mass and lean mass during weight loss, although fat generally accounts for the larger proportion of the weight lost.

This does NOT mean GLP-1 medications “eat your muscle,” as you may have heard on social media. What it does mean is that if you are losing a significant amount of weight, protecting your muscle needs to be part of the plan.

Muscle is not just about looking toned.

Muscle is so much more than what makes us strong or changes how our body looks. It is metabolically active tissue and plays an important role in how our body manages glucose, maintains insulin sensitivity, supports our bones, and keeps us strong and physically independent as we age.

In fact, skeletal muscle is one of the body's major sites for glucose disposal. After you eat carbohydrates and glucose enters your bloodstream, insulin helps signal your muscle cells to take up that glucose and either use it for energy or store it as glycogen for later. In simple terms, your muscles provide an important place for glucose to go. Maintaining healthy muscle mass and regularly using that muscle through movement and resistance training helps support insulin sensitivity, how effectively your cells respond to insulin and manage blood sugar.

Muscle also works closely with your bones. Resistance and weight-bearing exercise place healthy stress on the skeleton, helping stimulate the processes that maintain bone strength and bone mineral density. This becomes increasingly important as we age, when both muscle and bone mass naturally become more difficult to maintain.

Okay, and here is something we don't talk about nearly enough: muscle is one of our greatest investments in healthy aging.

Maintaining muscle helps preserve strength, balance, mobility, and the ability to perform everyday activities, from carrying groceries and climbing stairs to getting up from the floor. As muscle mass and strength decline, the risk of frailty, falls, and loss of independence increases.

This is why, particularly during significant or rapid weight loss, I don't just care about how much weight you lose. I care about WHAT you are losing.

The goal isn't simply to make the number on the scale smaller. We want to lose body fat while preserving as much metabolically important lean muscle as possible, and that requires intentionally giving your body two things it needs to hold onto muscle: adequate protein and resistance training.

It should be noted that this conversation becomes even more important for women navigating perimenopause or menopause because age-related and hormonal changes can already make maintaining muscle more challenging.

So when I am working with someone who wants to lose weight, I'm not interested only in what the scale says.

I want you losing fat while preserving as much muscle and strength as possible.

This is very different from simply becoming smaller.

How Do We Protect Muscle While Losing Weight?
The first piece is PROTEIN.

When your appetite drops dramatically, it is very easy to simply eat less of everything, including protein, and that's where we can run into trouble.

Protein provides the amino acids your body needs to maintain and repair muscle. Rather than giving everyone the same protein prescription, I individualize recommendations based on body size, age, activity level, medical history, kidney function, rate of weight loss, and overall goals.

That said, a commonly used range during active weight loss is approximately 1.2–1.6 grams of protein per kilogram of body weight per day, although individual needs vary.

I also do not want someone eating very little protein all day and trying to catch up with a huge piece of chicken at dinner. Spreading protein throughout the day gives you multiple opportunities to support muscle protein synthesis.

Think eggs or Greek yogurt at breakfast, chicken or beans at lunch, fish or another quality protein at dinner, and perhaps a protein-rich snack or shake if your appetite makes meeting your needs through meals difficult.

Protein is important, but it is only half of the equation. Your body also needs a reason to keep that muscle, and that’s where resistance training comes in. Protein provides the building blocks. Strength training provides the stimulus.

For most people, that means working toward resistance training at least two to three times per week, adjusted for fitness level and medical needs. Free weights, machines, resistance bands, body-weight exercises, and strength-based classes can all count.

Before you ask… yes, walking is wonderful. I am a huge fan of walking, especially after meals, for cardiovascular and metabolic health. But walking and strength training don't do exactly the same job. We need both.

When “I’m Not Hungry” Becomes a Problem
One of the benefits of these medications is that people who have spent years dealing with relentless hunger or “food noise” may finally experience relief. This is significant, but having very little appetite can create a different problem: chronic under-fueling.

Barely eating is not the goal.

If your food intake becomes too low, it becomes increasingly difficult to get enough protein, fiber, vitamins, minerals, essential fats, fluids, and electrolytes to support your body properly. That is why I get concerned when I hear someone say, “I’m doing great on my GLP-1. I barely eat!”

Eating as little as possible is NOT necessarily a sign that the medication is working well, and the goal should never be to see how little food you can survive on.

The goal is to improve your health.

When your appetite is reduced and you are eating less overall, the quality of what you eat becomes even more important. Every meal, and every bite, is an opportunity to provide your body with the protein and nutrients it needs to preserve muscle, maintain energy, support digestion, and protect your long-term health.

What About GLP-1 and Gut Health?
Here is where this gets even more interesting.

Your body naturally produces GLP-1 in specialized cells in the intestine, and the foods you eat can influence your gut environment and the release of several satiety hormones, including GLP-1.

Fiber is particularly important.

When certain fibers reach the colon, your gut bacteria ferment them and produce compounds called short-chain fatty acids. These compounds play numerous roles in gut health and metabolic signaling.

So instead of chasing a supplement claiming to “naturally mimic Ozempic,” I would much rather see you build a diet rich in a wide variety of plants and minimally processed foods.

The goal is to build your meals around a variety of whole, nutrient-dense foods that provide fiber, protein, healthy fats, and plenty of plant diversity. Include fiber- and prebiotic-rich foods such as oats, beans, lentils, chickpeas, quinoa, chia and flax seeds, berries, apples, onions, garlic, leeks, and asparagus, along with plenty of non-starchy vegetables like leafy greens, broccoli, Brussels sprouts, zucchini, peppers, cabbage, and cauliflower.

Pair these foods with quality sources of protein, including eggs, poultry, fish, lean meats, Greek yogurt, cottage cheese, tofu, tempeh, beans, and lentils, and healthy fats from extra-virgin olive oil, avocado, nuts, seeds, and fatty fish. Resistant starches, found in foods such as beans and lentils, green bananas, oats, and cooked-and-cooled potatoes or rice, can also help nourish beneficial gut bacteria. And, if you tolerate them, fermented foods such as plain yogurt, kefir, sauerkraut, kimchi, miso, and tempeh can add another layer of variety to a gut-supportive eating pattern.

You do NOT need to eat every food on this list. The bigger goal is variety, consistency, and gradually increasing the diversity of foods that nourish both you and your gut microbiome.

One important thing to remember…

When it comes to fiber, more is not always better, especially if you increase it too quickly. If you want to learn more about how much fiber you actually need, the different types of fiber, and how to increase your intake without making your gut miserable, read my blog, Fiber Is Having a Moment. But Are You Actually Eating Enough?

I need to make one thing VERY clear… eating these foods is not the nutritional equivalent of taking a GLP-1 medication.

Food absolutely plays a role in supporting your body’s natural GLP-1 production, gut-hormone signaling, blood sugar regulation, and appetite control; however, we need to be very clear about what nutrition can and cannot do.

Eating more fiber, adding chia seeds or avocado, increasing protein, or taking a supplement marketed as a “natural GLP-1” does not reproduce the pharmacological effects of medications like semaglutide, tirzepatide, or Retatrutide. These medications are specifically designed to activate hormone receptors at levels and for durations that food simply cannot replicate. Nutrition is incredibly powerful, but it is not medication, and we do not need to exaggerate what food can do in order to recognize how important it is.

Good nutrition supports your physiology; it does not mimic a prescription drug.

So Can You Naturally “Boost” GLP-1?
Technically, certain foods and behaviors can influence GLP-1 secretion, but I prefer the word support rather than “boost.” Your body already knows how to make GLP-1.

Protein, fiber, healthy fats, regular physical activity, adequate sleep, and an overall nutrient-dense dietary pattern can support normal appetite regulation, glucose control, gut health, and metabolic signaling.

These are not trendy “GLP-1 hacks.” They are the same foundational principles I have been teaching for years and that I dive deeper into in my book, Cracking The Food Code. The goal isn't to find one magical food or supplement, but to understand how food works with your individual biology and build sustainable habits that support your health over time.

There is no magical “natural Ozempic.”

There is no single supplement, drink, food, or morning routine that's going to suddenly transform your GLP-1 production. I know that is not nearly as exciting as what you may hear on TikTok.

But it's the truth.

The fundamentals still win: eat enough protein, gradually increase fiber, eat a wide variety of plants, choose minimally processed foods most of the time, strength train, walk, prioritize sleep, manage stress, and stay hydrated.

Not sexy.

But incredibly effective for supporting overall health.

What Happens If You Stop a GLP-1 Medication?
This is another part of the conversation that deserves more nuance.

Obesity is increasingly understood as a chronic disease, not simply a failure of willpower.

Research with semaglutide has shown that many people regain a significant amount of weight after treatment is discontinued. In the STEP 1 trial extension, participants regained approximately two-thirds of their previous weight loss during the year after stopping semaglutide. That doesn’t mean the medication “failed.”

Losing weight does not erase the biology that influences hunger, appetite, and body weight. That is why I do NOT love the advice, “Just use the medication until you learn better habits.” It’s not that simple.

Habits matter. Biology matters. And for some people, medication may be part of long-term care. That decision belongs between you and your medical provider, not in a social media sound bite.

Where I Think We Get This Wrong
I do NOT think GLP-1 medications should be viewed as either a miracle or a shortcut. They are medications, and for appropriately selected patients, they can be powerful tools for treating obesity, diabetes, and related metabolic disease.

However, as a Registered Dietitian, the number on the scale will never tell me everything I need to know.

I want to know:

• Are you getting enough protein?

• Are you maintaining muscle?

• Are you strength training?

• Are you getting enough fiber?

• Are you hydrated?

• How is your digestion?

• Are you constipated?

• Are you meeting your vitamin and mineral needs?

• Are you losing weight so quickly that you're struggling to nourish yourself?

• How is your energy?

• And just as importantly, how is your relationship with food?

That is where nutrition CARE comes in.

Medication + Nutrition: I Think This Is the Better Conversation
If you ARE taking a GLP-1 medication, nutrition should NOT become a contest to see how little you can eat. Instead, the goal is to make the food you are eating work harder for you, prioritizing protein to protect muscle, fiber-rich plants to support your gut and metabolic health, healthy fats, adequate hydration, and nutrient-dense foods, while incorporating strength training and continuing to work closely with your medical team.

And if you are NOT using medication? The fundamentals do not change. These same principles support blood sugar regulation, gut health, body composition, appetite regulation, muscle preservation, and long-term metabolic health.

This is what I love about nutrition: the fundamentals don’t suddenly stop mattering because we have a new medication.

Medication may change the tools we have available, but it doesn’t change what the body needs to be well nourished, strong, and metabolically healthy.

The Phil Knows Food Philosophy: RESET. REFUEL. REWIRE.
This is really what Phil Knows Food has always been about. It is the philosophy behind my book, Cracking The Food Code, and the foundation of the programs, tools, and education I create.

We RESET by stepping away from the habits and dietary patterns that may no longer be serving us and getting back to the fundamentals.

We REFUEL by giving the body what it actually needs: adequate protein, fiber-rich plants, healthy fats, nutrient-dense foods, hydration, movement, and yes, enough food.

And we REWIRE by moving away from deprivation, quick fixes, diet mentality, and all-or-nothing thinking and toward a better understanding of our bodies and habits we can actually sustain.

This philosophy doesn’t compete with medication, and it isn’t dependent on medication either. It is about building the foundation that supports your health regardless of which tools are part of your individual journey.

Whether you are taking a GLP-1 medication, considering one, or choosing a different path, the goal remains the same: protect your muscle, nourish your body, support your gut, improve your metabolic health, and build habits that work in real life.

Medications will change. Nutrition trends will come and go. New research will continue to evolve, but learning how to nourish your body and understanding WHY it matters never goes out of style.

The Bottom Line...
GLP-1 medications have changed the treatment of obesity and diabetes, and the science continues to evolve incredibly quickly.

Semaglutide targets GLP-1.
Tirzepatide targets GIP + GLP-1.

And Retatrutide is being studied as a triple agonist targeting GIP + GLP-1 + glucagon. The early Phase 3 results are impressive, but as of October 2026, Retatrutide remains investigational and is not FDA-approved.

These medications can be powerful tools.

But regardless of which tool you use, the fundamentals of health still matter.

Protein matters. Muscle matters. Fiber matters. Gut health matters. Strength matters. And the quality of the weight you lose matters, not just the number on the scale.

We do NOT need to choose between medication and lifestyle.

For many people, the best approach to metabolic health may include both.

And that is a conversation I think is worth having.

Taking a GLP-1 Medication? Let's Make Sure You're Nourishing Your Body.
Eating less isn't the goal. Getting healthier is.

Download my FREE GLP-1 Nutrition Checklist, a practical guide to help you protect muscle, meet your nutritional needs, support your gut, and feel your best while taking a GLP-1 medication.

From protein and fiber to hydration, strength training, and overall well-being, this checklist helps you look beyond the number on the scale and focus on what really matters.

DOWNLOAD THE FREE GLP-1 NUTRITION CHECKLIST

Progress Over Perfection. Always.

Phil

Philippa “Phil” Bebbington, MS, RD
Phil Knows Food | Nutrition That Makes Sense

Disclaimer
This article is for educational purposes only and is not intended to diagnose, treat, or replace individualized medical care. Prescription medications should be used under the supervision of an appropriate healthcare provider.