How GLP-1 Affects the Brain, Part 1: What We Know So Far
Chances are, you’ve heard of GLP-1 and GLP-1-mimicking medications in recent years. Their meteoric rise in popularity — fueled by brand names like Ozempic, Wegovy, and Mounjaro — has reshaped the way we think about weight loss, blood sugar control, and metabolic health. These medications are known as GLP-1 receptor agonists, and their demand is far from slowing down. It is estimated that an astonishing 12% of American adults have taken GLP-1 medications; that’s almost one in every eight adults.*
Not surprisingly, their widespread use has provoked plenty of questions regarding potential long-term side effects, especially with how these medications may affect the brain. In this two-part series, we’ll look at the link between GLP-1s, nutrition, metabolic health, and, of course, brain health.
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Today in Part 1, we’ll unpack what GLP-1 is, how it works, and explore how these drugs affect nutrition and brain-related side effects. We’ll also address common myths, GLP-1 and nutritional deficiency, and why supporting your brain while on these medications is more important than it might seem.
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In Part 2, we’ll dive deeper into the science of GLP-1s and the brain — looking at why and how these medications are being studied for Alzheimer’s disease and cognitive decline, and what the research says (and doesn’t say) about their potential long-term impact on brain health.
Whether you are using a GLP-1 medication, know someone who is, or you’re simply curious how these drugs interact with the brain and body, our goal is to provide clarity and insight on this hot topic.
What Is GLP-1 and How Does It Work?
GLP-1 stands for glucagon-like peptide-1, a hormone your body naturally releases after you eat. It plays a key role in regulating blood sugar and appetite. Think of it as part of your body’s built-in system for managing meals — it helps your pancreas release insulin, slows down how quickly your stomach empties, and tells your brain you’re full. There are even GLP-1 receptors in the brain, specifically in the hypothalamus and brainstem, which manage hunger and energy balance.1
GLP-1 receptor agonists (GLP-1 RAs) — medications like Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda, Trulicity, and Victoza — are designed to mimic the GLP-1 hormone and amplify its effects. They were initially developed to assist in managing blood sugar levels for patients with type 2 diabetes, but these drugs have helped people lose significant weight, expanding their use far beyond diabetes treatment. 2 Their popularity has even reached younger, non-obese individuals seeking to suppress their appetite and quickly slim down.
Some GLP-1 Truths and Myths
The extensive discussion surrounding GLP-1 RAs has generated numerous misconceptions among the facts of these medications.
Clinical Successes
Clinically speaking, these medications can lead to an average of 15-25% reduction in body weight after one year, which is similar to patients who have undergone bariatric surgery.3 GLP-1 RAs have even been shown to reduce A1C (a marker for diabetes) by 0.7% on average.4 Lastly, they can successfully suppress appetite thanks to the GLP-1 receptors located within both the gut and the brain.
Real-World Limitations
There is no such thing as a perfect medication. These drugs mostly work in conjunction with a healthy diet and lifestyle. Short-term GLP-1 side effects include nausea, constipation, and reflux, and many individuals stop use due to the constant GI issues. When people decide to stop, the effects of the medications are often reversed, and the weight regained can be proportional to the amount lost.5
Are You Losing Fat or Muscle on GLP-1s?
The weight lost with GLP-1 medications isn’t just unnecessary fat. Studies show that around 45% of weight lost by semaglutide (Ozempic, Wegovy) users and 25% by tirzepatide (Mounjaro, Zepbound) users comes from lean muscle mass.6 The majority of individuals on a GLP-1 RA are middle-aged women, and this loss of lean muscle can lead to worsened metabolic health, bone density, and strength, which are essential for healthy aging — potentially harming their independence and quality of life.
The Hidden Side Effects of GLP-1s
While flaunted in the media as a dieting fad, these medications are powerful metabolic regulators that do much more to the body than merely slim it down. They impact multiple internal systems including the gut, heart, muscles, bones, and brain. Broader side effects include GI upset as well as dry mouth, mood changes, and potential thyroid and pancreatic concerns.7 Outside of clinical studies, social media users and health advocates have anecdotally reported effects from GLP-1 RAs, ranging from brain fog and low stamina to more extreme reactions like severe nausea and GI distress. (Reddit, Reddit)
Why GLP-1s May Not Be a Forever Fix
A major problem for GLP-1 medications is how difficult it is to stick with them long-term. Even for those who see impressive early results, staying on these medications isn’t easy, or common. One study found that nearly half of users stopped treatment within a year, while another, focused on non-diabetic adults with obesity, reported just 32% remained adherent after 12 months.8,9 Common reasons for stopping include the challenging side effects, high costs, drug shortages, and lack of perceived benefit. GLP-1s can be a powerful catalyst, but they’re not a replacement for long-term choices that support both physical and brain health.
Why Nutrition is Crucial During GLP-1 Use
GLP-1s suppress appetite, but they don’t suppress your body and brain’s need for nutrients.
A 2025 study reported that 22% of GLP-1 RA users were diagnosed with at least one new nutrient deficiency by the 12-month mark, and another analysis found significant declines in the intake of multiple key nutrients — especially iron, magnesium, calcium, potassium, vitamins A, C, D, E, K, and B12.10, 11 These aren’t fringe nutrients; they are the heavy hitters your body needs for energy metabolism, immune function, and yes, brain health. Omega-3 intake has also been shown to decline, likely due to people cutting back on calorie-dense (but brain-boosting) foods like healthy fats (think fatty fish and olive oil) and nuts. Eating less doesn’t just mean fewer cookies, it also means fewer leafy greens, whole grains, and essential nutrients, too.
These deficits aren’t always immediately apparent, but they accumulate over time. A little dizziness here, some brain fog there. Maybe you’re cold all the time, you notice your hair thinning, or your mood seems off. These are signs of nutrient deficiencies, and they’re common in people taking GLP-1 RAs without adjusting their diets to match. That’s why these medications work best when paired with proactive changes. Studies are increasingly showing that GLP-1 medications are most effective (and least disruptive) when users increase physical activity, eat nutrient-dense foods like beans, berries, eggs, and fatty fish, supplement as needed, and pay attention to hydration and sleep.12
If you're using or considering a GLP-1 medication, it's important to know which key nutrients help support your brain. Download the FREE 19-page guide, 10 Nutrients Your Brain Needs, where inside, you'll learn about the most brain-beneficial forms of each nutrient, signs of deficiency, food sources to prioritize, and easy ways to incorporate them into your meals.
What GLP-1s May Do to Your Brain
Many think that if GLP‑1 RAs can help with weight loss, they might naturally boost brain function, too. Better metabolic health can support mood and focus, but that’s only part of the picture.
A recent study reported neurological complaints early in GLP‑1 RA use — although it was chalked up to correlation, not necessarily causation.13 As we previously mentioned, drug-induced appetite suppression leads to nutrient deficiencies, which can cause brain fog, fatigue, mood shifts, and memory blips over time.
An additional study explored the vitamins, minerals, and nutrients that GLP-1 users typically fall short on, and how these are essential for neurochemical balance and cognitive function.11 Low B12 can dampen memory, choline deficiency can dull focus, and inadequate omega‑3s can interfere with mood regulation — so what may seem like a side effect of the drug could actually stem from underlying nutritional gaps.
As research continues, one thing remains clear: brain health and nutrition are closely intertwined. Stay tuned for Part 2, where we’ll dig into GLP‑1 RAs and long-term brain outcomes.
The Takeaway: GLP-1s Are a Tool, Not a Fix-All
Speak with your healthcare provider before starting any new medication. While the information in this article is not medical advice, science-backed proactive dietary and lifestyle changes could potentially support those currently using or considering a GLP-1 medication.
GLP-1 weight loss can be significant, but it’s not a magic bullet. When your body is shifting and recalibrating, brain-supportive lifestyle choices become even more critical. Think: balanced meals, regular exercise, quality sleep, and supplementation. These habits are what help protect your health,and your brain, long after the injections stop.
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Whether your goal is to support long‑term brain health, stay sharp during your weight loss journey, or to help ensure you’re giving your body what it needs, RELEVATE is a practical choice.
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References
* KFF Health Tracking Poll May 2024: The Public’s Use and Views of GLP-1 Drugs | KFF. (n.d.). Retrieved July 22, 2025, from https://www.kff.org/health-costs/poll-finding/kff-health-tracking-poll-may-2024-the-publics-use-and-views-of-glp-1-drugs/
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