Mark G. Agresti, MDMARK G. AGRESTI MD LLC · PALM BEACH, FLORIDA

GLP-1 DRUGS · PLAIN ENGLISH GUIDE · 2026

Ozempic, Wegovy & Zepbound:

The Complete Guide

What these drugs really do, who they help, what they risk — and why a psychiatrist thinks they may be the most important brain drugs of our lifetime.

By Mark G. Agresti, MD | Mark G. Agresti MD LLC | drmarkagresti.com | Palm Beach, Florida | April 2026

By now you have heard of Ozempic. Maybe you have a friend on it. Maybe your doctor mentioned it. Maybe you have seen the before-and-after photos flooding social media. These drugs — Ozempic, Wegovy, Zepbound, Mounjaro — have become some of the most talked-about medications in history. And for good reason: they work remarkably well for weight loss.

But here is what most people — and many doctors — do not fully appreciate: these are brain drugs. They act on reward circuits, dopamine pathways, and addiction centers deep inside your brain. That is why they crush food cravings so effectively. And it is also why they are showing up in research on alcohol addiction, opioid dependence, gambling disorder, depression, bulimia, and more.

I am Dr. Mark G. Agresti, a psychiatrist in Palm Beach, Florida, and the founder of Mark G. Agresti MD LLC. My goal with this article is simple: give you the complete picture — the good, the bad, and everything in between — in plain language that anyone can understand. No jargon. No fluff. Just what you need to know.

First: What Are These Drugs?

GLP-1 stands for glucagon-like peptide-1. It is a hormone your gut naturally produces when you eat. It tells your brain you are full, tells your pancreas to release insulin, and slows down digestion. GLP-1 drugs mimic this hormone — but stronger, and longer-lasting than anything your body makes naturally.

Here are the main players you have probably heard of:

Ozempic

Semaglutide

FDA approved for type 2 diabetes. Widely used off-label for weight loss. Weekly injection.

Wegovy

Semaglutide (higher dose)

FDA approved for weight loss in adults AND teens 12+. Same drug as Ozempic, higher dose.

Zepbound

Tirzepatide

FDA approved for weight loss. Dual GLP-1 + GIP agonist. Even greater weight loss than semaglutide alone.

Mounjaro

Tirzepatide

FDA approved for type 2 diabetes. Same drug as Zepbound. Often used off-label for weight loss.

Saxenda

Liraglutide

Older GLP-1, FDA approved for weight loss. Daily injection. Approved for teens 12+.

Victoza

Liraglutide

Same as Saxenda, approved for type 2 diabetes. Also used in addiction research.

They all work the same basic way — mimicking GLP-1 — but differ in potency, dosing frequency, and which other receptors they also target. Zepbound and Mounjaro hit an additional hormone receptor (GIP), which is why they tend to produce even greater weight loss.

How They Work in the Brain — This Is the Big Deal

Here is the part your weight loss doctor probably did not explain. GLP-1 receptors are not just in your gut. They are scattered throughout your brain — including in regions that control:

Hunger and appetite (hypothalamus)
Pleasure and reward (nucleus accumbens, ventral tegmental area)
Cravings and addiction (mesolimbic dopamine system)
Mood and memory (hippocampus, prefrontal cortex)
Stress and anxiety (amygdala)

When GLP-1 drugs activate receptors in the brain’s reward system, they turn down the dopamine response to pleasurable things. That is how they kill food cravings so effectively — your brain stops getting that big “reward hit” from eating. But here is the catch: dopamine does not have separate circuits for food versus alcohol versus gambling versus opioids. When you turn down the reward signal for one thing, you turn it down for everything.

That is simultaneously the most exciting and most concerning thing about these drugs.

“GLP-1 drugs are not just metabolic medications. They are dopamine modulators. That puts them squarely in the territory of psychiatry — and it means we need psychiatrists involved in monitoring and prescribing, not just endocrinologists and weight loss clinics.”— Mark G. Agresti, MD · Mark G. Agresti MD LLC · Palm Beach, Florida

Preclinical studies show reduced cocaine-seeking behavior. NIDA funding research now. Not yet studied in humans in formal trials.

PRECLINICAL ONLY

The one major exception: Anorexia Nervosa. GLP-1 drugs are essentially contraindicated in anorexia. They suppress appetite aggressively — which is dangerous and potentially life-threatening in someone who is already severely restricting calories. There are documented cases of people with anorexia misusing these drugs to accelerate restriction. This is a serious safety concern.

The Side Effects — All of Them, Honestly

No sugarcoating here. These drugs have real side effects, and some of them are things most prescribers do not bring up in the brief appointment where they hand you the prescription. Here is the full picture:

VERY COMMON (50–60% OF USERS)

Nausea — especially when starting or increasing dose
Diarrhea
Constipation
Vomiting
Burping / belching
Stomach cramping
Bloating and gas
Fatigue
Headache
Heartburn / acid reflux

SERIOUS SIDE EFFECTS

Gastroparesis — stomach stops emptying properly
Bad breath from slow gastric emptying
Pancreatitis — inflammation of the pancreas
Bowel obstruction in rare cases
Thyroid tumors (seen in animals; monitoring advised)
Severe dehydration from vomiting or diarrhea
Aspiration risk under anesthesia — crucial to tell your surgeon
Vision changes (rare — called NAION)
Allergic reactions at injection site

LONG-TERM CONCERNS

Muscle loss — up to 40% of weight lost can be lean muscle
Bone density loss — especially in older adults and teens
Hair loss (telogen effluvium from rapid weight loss)
Nutritional deficiencies from eating less
Weight regain if you stop the drug
Unknown effects of decade-long use
Menstrual irregularities in some women
Potential psychiatric effects (see below)

Let’s Talk About the Gastroparesis and Bad Breath Issue

This is one of the most common quality-of-life complaints that patients don’t expect. GLP-1 drugs slow down how fast your stomach empties food into your intestines — this is called gastroparesis, or delayed gastric emptying. When food sits in your stomach longer than it should, it ferments, produces gas, and causes that distinctive sulfur-like bad breath that many Ozempic users report.

It can also cause loud, embarrassing burping, a constant feeling of fullness even hours after eating a small meal, and in some people, it progresses to true gastroparesis — a serious condition where the stomach essentially stops moving food through normally. This is rare but documented, and anyone with nausea and vomiting that is getting worse rather than better needs medical attention.

The Muscle Loss Problem — This Is More Serious Than You Think

Here is something that should be in every conversation about these drugs but usually is not: when you lose weight on GLP-1 drugs, a significant portion of what you lose is muscle, not just fat. Studies show that 15–40% of weight lost on these medications comes from lean muscle mass. For a person who loses 50 pounds, that could mean losing 10–20 pounds of actual muscle.

Muscle is not just cosmetic. It is your metabolic engine, your long-term strength, your protection against falls and fractures as you age, and a major driver of insulin sensitivity. Losing muscle while taking a metabolic medication is a significant problem that requires an active counter-strategy: resistance training (weight lifting) and adequate daily protein intake — at least 1.2 grams of protein per kilogram of body weight.

If you are on a GLP-1 drug and not doing any resistance exercise or paying attention to protein, you may be winning the weight war but quietly losing the muscle war.

💜 A Special Note for Teenage Girls — and Their Parents

Wegovy is FDA approved for adolescents 12 and older with obesity. But teenagers are not small adults. Their bodies and brains are still developing, and the risks of GLP-1 drugs look different — and in some ways more serious — in this age group.

What teenage girls specifically need to know:

Bone density: Adolescence is the single most critical window for building peak bone density. Rapid weight loss and reduced caloric intake during this window can permanently reduce lifetime bone strength, increasing fracture risk now and osteoporosis risk in adulthood.
Muscle development: Teens are still building their foundational muscle mass. Losing lean mass during this period can affect long-term strength and metabolism in ways that are not easily reversed.
Brain development: The adolescent brain is still forming. GLP-1 drugs act on dopamine reward circuits — the same circuits that are being calibrated during adolescence. The long-term effects of this on the developing teenage brain are simply unknown.
Eating disorder risk: Teens — especially girls — already face enormous social pressure around food, body image, and weight. A powerful appetite suppressant in this environment can trigger or accelerate disordered eating, even if that was never the intention.
Menstrual changes: Many girls report irregular periods on GLP-1 drugs. Significant weight loss also affects reproductive hormones.
Mood changes: Emotional flatness, reduced joy, and anhedonia are reported in some users. In a teenager already navigating the emotional challenges of adolescence, these effects can be significant and should not be dismissed.

Bottom line for parents: If your daughter is being prescribed Wegovy or any GLP-1 medication, she should be seen by a psychiatrist — not just an endocrinologist or pediatrician — before starting and regularly throughout treatment. Dr. Mark G. Agresti at Mark G. Agresti MD LLC in Palm Beach offers exactly this kind of monitoring.

Why These Are Psychiatric Drugs — And Why That Matters

I want to make this argument clearly, because I think it is one of the most important points in this entire article: GLP-1 drugs are dopamine-modulating psychiatric medications that happen to also cause weight loss. We have it backward. We are treating them as weight loss drugs that have psychiatric side effects. The reality may be the reverse.

Think about what they actually do in the brain:

They reduce reward-seeking behavior — which is the core mechanism of addiction treatment
They promote neurogenesis (new brain cell growth) in the hippocampus — which is what antidepressants do
They reduce neuroinflammation — increasingly linked to depression, bipolar disorder, and psychosis
They modulate the stress response — relevant to anxiety, PTSD, and burnout
They influence the gut-brain axis — an emerging frontier in psychiatric research

A drug that does all of those things should have a psychiatrist involved in its prescription and monitoring. The fact that the vast majority of GLP-1 prescriptions are written without any psychiatric assessment is, in my view, a serious gap in how we are deploying these medications.

⚠ People Who Should NOT Take GLP-1 Drugs (or Need Extreme Caution)

Active anorexia nervosa or any restrictive eating disorder
History of pancreatitis
Personal or family history of medullary thyroid carcinoma
Pregnancy or planning pregnancy
Severe kidney disease
Pre-existing gastroparesis
Active suicidal ideation — the FDA is still investigating psychiatric risks
Sarcopenia (very low muscle mass) without active resistance training plan
Severe osteoporosis without monitoring plan

Frequently Asked Questions

Can Ozempic help with alcohol addiction?

Yes, and this is one of the best-supported emerging uses. A 2025 randomized controlled trial published in JAMA Psychiatry found that semaglutide significantly reduced alcohol cravings and how much people drank over nine weeks compared to placebo. The mechanism — blunting dopamine reward from alcohol — is the same reason it suppresses food cravings.

Does Ozempic cause muscle loss?

Yes, and this is underappreciated. Studies show 15–40% of total weight lost on GLP-1 drugs can come from lean muscle mass. The solution is resistance exercise and eating adequate protein — at least 1.2g per kg of body weight per day. Without this, you may be losing metabolically critical muscle along with fat.

Why does Ozempic cause bad breath?

GLP-1 drugs slow stomach emptying (gastroparesis effect), causing food to ferment longer in the gut. This produces sulfur-type gases that cause bad breath and burping. Eating smaller, slower meals and staying hydrated can help. If symptoms are severe or getting worse, tell your doctor — it may signal true gastroparesis.

Can teenagers take Wegovy or Ozempic safely?

Wegovy is FDA approved for teens 12 and older with obesity, but “approved” does not mean “without significant risk.” Teens face unique concerns around bone density, muscle development, brain development, eating disorder risk, and mood changes. Any teenager on a GLP-1 drug should be monitored by a psychiatrist, not just a pediatrician or endocrinologist.

Will I gain the weight back if I stop taking Ozempic?

Most people do regain significant weight after stopping GLP-1 medications — studies show an average of two-thirds of lost weight returns within a year of stopping. This has led many physicians to view these as long-term or lifelong medications, similar to blood pressure drugs, rather than short-term interventions.

Can GLP-1 drugs help with gambling addiction?

There is no clinical trial data yet specifically on gambling disorder, but the mechanism is highly plausible — gambling disorder is fundamentally a dopamine reward disorder, and GLP-1 drugs blunt dopamine reward responses. Anecdotal patient reports are consistent. This is an area to watch. Off-label use is being explored by some addiction psychiatrists.

What about benzodiazepine dependence?

This is essentially unstudied. Benzodiazepines work on GABA receptors rather than dopamine — a different system — which may be why GLP-1 research has not focused here. It is an open frontier. Anyone trying to taper off benzodiazepines should work with a psychiatrist regardless of whether GLP-1 drugs are involved.

On a GLP-1 Drug and Concerned About Your Mood?

Dr. Mark G. Agresti, MD provides expert psychiatric evaluation and monitoring for patients on Ozempic, Wegovy, Zepbound, and other GLP-1 medications in Palm Beach, Florida — including adolescents and young adults.

SCHEDULE A CONSULTATIONMark G. Agresti MD LLC · Palm Beach, Florida · drmarkagresti.com

Medical Disclaimer: This article is written for educational and informational purposes by Mark G. Agresti, MD of Mark G. Agresti MD LLC, Palm Beach, Florida. It is not a substitute for professional medical advice, diagnosis, or treatment. Never start, stop, or change any medication without consulting your physician. If you are experiencing a mental health crisis, contact 988 (Suicide and Crisis Lifeline) or your nearest emergency room immediately.

Ozempic, Wegovy & Zepbound: The Complete Guide | Dr. Mark Agresti

Ozempic, Wegovy & Zepbound:

First: What Are These Drugs?

How They Work in the Brain — This Is the Big Deal

Every Use — Approved and Emerging

🏆 Type 2 Diabetes

⚖️ Weight Loss / Obesity

❤️ Heart Disease Prevention

🍺 Alcohol Use Disorder

💊 Opioid Use Disorder

🚬 Nicotine / Smoking

🎰 Gambling Disorder

🍽️ Binge Eating Disorder

😔 Bulimia Nervosa

🧠 Depression

😰 Anxiety Disorders

🛒 Shopping / Other Compulsions

🫁 Sleep Apnea

🫀 Fatty Liver Disease

🧊 Cocaine / Stimulant Use