The Core 4: The Foundation Every GLP-1 Journey Is Built On
Eating less shouldn't mean getting less of what your body needs. These four supplements cover the gaps, in every phase.
Key takeaways
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Eating less doesn't usually create one deficiency — it creates small gaps across many nutrients at once. That's why the foundation is four products, not one.
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The Core 4: a high-quality multivitamin, vitamin D3 with K2, a synbiotic, and magnesium.
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A 2025 joint advisory from four leading medical and nutrition organizations identified these nutrients as important considerations throughout GLP-1 therapy.
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For most people, the Core 4 is the whole supplement plan. Everything else is added only when there's a specific reason.
Not sure which phase you're in, or what to add on top of the foundation?
The Most Common Question We Hear — and Why It's the Wrong One First

One of the most common questions we hear is: "What supplements should I take while I'm on Ozempic or Wegovy?"
It's an important question. But it's not the first one.
Because eating less rarely creates one nutritional deficiency. It creates small gaps across many nutrients at the same time.
That's why the answer isn't one supplement. It's a foundation.
GLP-1 medications reduce food intake by 16 to 39 percent. That's how they help people lose weight, and it's also why those gaps open up: less protein, fewer vitamins and minerals, less fluid, and fewer electrolytes reaching a body that still needs all of them. In a study of more than 461,000 adults on GLP-1 therapy, nearly one in five developed a nutritional deficiency within their first year, vitamin D most commonly, followed by iron and B vitamins. Many had no symptoms while it was happening.
None of this surprised us. Medications that change how the body absorbs or uses nutrients have been part of pharmacy practice for a long time and helping people address that kind of depletion is work we've done for decades. GLP-1's are simply the newest example, and one of the most significant.
The medication changes how much you eat. It doesn't change what your body still needs.
Think of the Core 4 as the nutritional foundation that stays with you from your first injection through long-term maintenance, and even as you transition off medication.
Nutrient Depletion Isn't New to Us
Long before GLP-1 medications existed, helping people replace what their medications quietly deplete was central to what we do. That's more than sixty years of watching how drugs and nutrients interact, and it's why the Core 4 reflects both the published research and what our clinical nutritionists see in practice every day. It's also why our first instinct is always to recommend less, not more.
Your Nutritional Foundation: Meet the Core 4
1. High-quality multivitamin
A multivitamin is the widest net you can cast.
Best for:
- Broad nutrient coverage
- Everyday energy
- Immune function
- The wide-ranging gaps that open when you eat less
Why it matters. It covers the vitamins and minerals your body draws on every day for energy, immune function, tissue repair, and metabolism, rather than leaving you to guess which specific gap opened up.
What to look for. Active, bioavailable forms: methylated B vitamins and chelated minerals rather than the cheapest available versions. For women, a formulation that accounts for iron before menopause and includes bone-supportive nutrients does extra duty.
What we recommend. Our Pathway Essentials Coenzymated Multivitamins use B vitamins in their active, ready-to-use forms — no conversion required. Three options, so you can choose the one that fits:
→ Coenzymated Advanced Men's Multi
→ Coenzymated Pro Advanced Women's Multi — accounts for iron needs before menopause
→ Coenzymated Once Daily Multi, No Iron — for anyone who doesn't need supplemental iron, or takes it separately
2. Vitamin D3 with K2
Best for:
- Bone health
- Immune support
- Muscle function
- Steady support for long-term GLP-1 use
Why it matters. Vitamin D insufficiency is already widespread before treatment begins. Rapid weight loss then accelerates bone remodeling, a process that depends on steady vitamin D. K2 works alongside D3 to help direct calcium where it's needed most.
What to look for. D3 (cholecalciferol) rather than D2, paired with K2. This is one worth knowing your number on. If you've had your levels tested, that result should guide your dose.
What we recommend. Pathway Essentials Vitamin D3 + K2 pairs cholecalciferol with vita MK-7, the well-researched MK-7 form of K2. It comes in two strengths so you can match your intake to your needs — and it's the one Core 4 supplement where bloodwork, not guesswork, should drive the dose. Our team can help you interpret yours.
3. Synbiotic
Best for:
- Digestion
- Gut comfort
- Microbiome balance
- The gut changes that start in week one
Why it matters. GLP-1 medications change gut motility from the earliest weeks, and those changes continue throughout treatment. A comprehensive synbiotic, probiotics with prebiotic and postbiotic support, helps maintain gut barrier health and a balanced microbiome, which support healthy digestion and nutrient absorption.
What to look for. Clinically studied ingredients, multiple strains with meaningful CFU counts, plus the prebiotic fiber that feeds them.
What we recommend. Humanized Nutrition Pro Advanced Synbiotic is built for exactly this job. It delivers all three layers of gut support in one daily capsule: clinically studied probiotic strains, the prebiotic fiber that feeds them, and the postbiotic compounds that support your gut barrier.
4. Magnesium
Best for:
- Sleep
- Energy
- Muscle function
- Stress resilience
Why it matters. Magnesium supports hundreds of essential processes throughout the body, and it's one of the nutrients most likely to fall short as food intake decreases. It supports muscle function, energy, sleep quality, stress resilience, and regularity, all of which come under more pressure during treatment.
What to look for. Magnesium glycinate is generally the best-tolerated form and the most supportive of sleep and stress resilience. Magnesium oxide is common and inexpensive, but poorly absorbed.
What we recommend. Pathway Essentials Magnesium Glycinate 400 mg — gentle on a stomach that's already digesting slowly, well absorbed, and the form best suited to sleep and stress support, which is why we suggest taking it in the evening. Available in two sizes, depending on whether you'd rather restock often or stock up.
How to Take Your Core 4
|
Supplement |
When to take it |
On a GLP-1, this matters because |
|
Multivitamin |
With food, improves absorption and eases stomach upset, which counts for more when digestion is already slow |
Covers the broad nutrient gaps that open when you're eating less across the board |
|
Vitamin D3 + K2 |
With your largest meal, it's fat-soluble, so some fat helps it absorb |
Supports the bone remodeling that rapid weight loss speeds up, and levels are often low before you even start |
|
Synbiotic |
Daily, at any consistent time, benefits build with steady use, so not missing days matters more than the hour |
Supports the gut, which shifts from the earliest weeks on a GLP-1 and shapes digestion and nutrient absorption |
|
Magnesium glycinate |
Evening, 30–60 min before bed, the glycinate form supports relaxation, so nighttime suits it best |
Replaces one of the first minerals to fall short on lower intake, and supports the sleep and regularity that can get harder |

Why We Chose These Four
In 2025, four leading medical and nutrition organizations, the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society, published a joint advisory on nutritional priorities during GLP-1 therapy. It identified the nutritional gaps that matter most during treatment as an ongoing priority, not just an early-months concern, which are the same gaps the Core 4 is designed to fill.
That doesn't mean everyone on a GLP-1 will become deficient. It means the odds climb when you're eating significantly less, and broad, consistent coverage is the sensible response to a predictable risk. The advisory told us nothing we didn't already know. We've spent decades helping people replace what their medications quietly take.
Start Here. For Most People, This Is All You Need.
The Core 4 covers the nutrient gaps that open for almost everyone on a GLP-1. For most people, it's not the first four items on a long list, it's the whole plan.
Food comes first. The Core 4 fills what food can't. Anything beyond that is added only when there's a real reason: a specific phase, a need your diet isn't meeting, or a symptom you want extra support for.
We'd rather you take four things well than ten things halfway. So if you're wondering whether you need more than the foundation, there's an easy way to find out. Take the assessment, or have a quick chat with our team of nutrition experts.
Three of the four come with a choice: which multivitamin fits you best, which vitamin D strength matches your levels, how much magnesium to keep on hand. The foundation is the same for everyone. the products that fill it aren't. So rather than piecing it together yourself, build your foundation in one place.
What Sits on Top of the Foundation
The Core 4 is what doesn't change. Beyond it, some phases call for one or two targeted additions — but only when food and the foundation aren't already covering the need. Nobody needs all of these; you add the two that fit your phase, if you need them at all.
The Core 4 is what doesn't change. Beyond it, some phases call for one or two targeted additions, but only when food and the foundation aren't already covering the need. You add only what fits your phase, and only if you need it.
|
Phase |
Possible Phase-Specific Support |
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Phase 1 · Just Starting |
Digestive support + active B12 |
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Phase 2 · Actively Losing |
Creatine monohydrate + collagen peptides |
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Phase 3 · Plateau |
Stress support + therapeutic-dose omega-3 |
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Phase 4 · Maintenance |
Creatine monohydrate + therapeutic-dose omega-3 |
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Phase 5 · Transitioning Off |
Blood sugar support + appetite regulation |

The foundation stays the same. The support evolves with your body.
Not Sure Where to Start?
Whatever phase you're in, the foundation is the same, and it's the most important place to begin.
Still not sure whether you need more than the Core 4? Our free GLP-1 Nutrition Assessment identifies your phase in about two minutes. Your personalized report covers your nutrition targets for protein, fiber, and hydration, your priority additions if you need them, the lifestyle habits that matter most, and what to focus on right now.
Get Your Personalized Phase Report ►
And if you'd like guidance built entirely around you, we're here for that too. Our clinical nutrition team offers one-on-one consultations, full reviews of your health history and labs, and personalized protocols tailored to exactly what your body needs.
Book a Nutrition Consultation ►
GLP-1 medications can be powerful. But eating less shouldn't mean getting less of what your body needs.
Build your foundation first. Then let your phase guide the rest.
References
- Mozaffarian, D., et al. "Nutritional Priorities to Support GLP-1 Therapy for Obesity: A Joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society." Obesity (Silver Spring), 2025;33(8):1475–1503.
- Butsch, W.S., et al. "Nutritional Deficiencies and Muscle Loss in Adults with Type 2 Diabetes Using GLP-1 Receptor Agonists: A Retrospective Observational Study." Obesity Pillars, 2025. Real-world claims analysis of 461,382 adults newly prescribed GLP-1 therapy.
- White, C.M., Tai, Z., Nuzi, K. "Transdermal 'Natural GLP-1' Dietary Supplements Violate Law and Place Patients at Risk." Annals of Pharmacotherapy, 2026.
- GLP-1 medication and food intake reduction. STEP and SURMOUNT clinical trial data and related literature.
- NIH Office of Dietary Supplements — Fact Sheets for Health Professionals: Vitamin D, Vitamin K, Magnesium, Multivitamin/Mineral Supplements.
These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. The information in this article is educational and is not a substitute for advice from your healthcare provider.
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