Weight-Loss Medications For Dummies
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If weight-loss medications feel confusing or overwhelming, you’re not alone. This Cheat Sheet brings the most important ideas together in one place. It gives you a clear overview of modern weight-loss medications, including GLP-based treatments as well as what side effects to watch for. It also explains how to balance nutrition and activity and highlights additions and alternatives that might aid in your weight-loss journey.

Weight loss is about biology, environment, and support, and medications are tools, not cures. Because most people need more than one strategy to succeed, learning how your options work helps you make better decisions. So use this Cheat Sheet whenever you need clarity or reassurance.

Demystifying weight-loss medication terminology

Between generic and brand names, medications can already be confusing, but with all the acronyms — not to mention that one medication could have two brand names (one for weight loss and one for type 2 diabetes) — navigating medications and their associated terminology can get confusing. Keep this list handy as a reference to keep it all straight:

  • GLP-1 receptor agonists are medications that act like a natural hormone. They reduce hunger and increase fullness.
  • GLP-RA is used as a broad, all-encompassing term. It refers to all weight-loss medications on the market that use GLP-1, either alone or in combination with GIP. Some newer medications combine GLP-1 with another hormone called GIP, which helps control blood sugar and appetite even better and can lead to greater weight loss for many people.
  • GLP-1 refers to glucagon-like peptide 1.
  • GIP refers to glucose dependent insulinotropic polypeptide.
  • Chronic disease means a condition that needs ongoing care over time.
  • Weight regain is a common biological response when treatment or support stops. It is not a personal failure.  
  • TBWL stands for total body weight loss. It is the percentage of your starting body weight that you lose over time. For example, if you weigh 200 pounds and lose 20 pounds, that equals 10 percent total body weight loss.

FDA-approved weight-loss medications

Obesity is a chronic medical condition. Many people need treatment over time, just like they would for high blood pressure or diabetes. So modern weight-loss medications work by changing biology, not willpower. Many of them affect hormones that control hunger and fullness. Some also slow digestion and improve blood sugar control. These changes help people eat less and feel more satisfied.

The FDA has approved several different types of weight-loss medications. When discussing medications with your doctor, you can use this table as a reference. Not only will you consider how much weight you could potentially lose, but you should also think about how the medications work (their mechanism) as well as how you administer them. Some mechanisms may work better for you than others, and you may be more consistent with a medication taken weekly, rather than daily.

Generic (brand) Mechanism Administration Percent weight loss
Semaglutide (Wegovy) GLP-1 Weekly injectable 15%
Liraglutide (Saxenda) GLP-1 Daily injectable 8%
Tirzepatide (Zepbound) GLP-1 and GIP Daily injectable 20%
Exenatide (Byetta) GLP-1 Twice-daily injectable 5–10%
Orlistat (Alli [OTC], Xenical) Reduces fat absorption Oral 5–7%
Phentermine-topiramate (Qsymia) Appetite suppressant Oral 9–10%
Naltrexone-bupropion (Contrave) Acts on appetite regulation centers Oral 5–8%
Phentermine (Adipex-P, Lomaira) Appetite suppressant Oral 5%

Nutrition based on your activity level

Medications can support weight loss, but they do not replace healthy eating or movement. Stay focused on long-term health by balancing nutrition with your level of exercise.

Activity Level Protein (g/lb/day) (g/kg/day) Fat (g/lb/day) (g/kg/day) Carbs (g/lb/day) (g/kg/day)
Sedentary/low activity 0.55–0.64 (1.2–1.4) 0.36–0.45 (0.8–1.0) 1.14–1.36 (2.5–3.0)
Moderate activity 0.64–0.73 (1.4–1.6) 0.45–0.55 (1.0–1.2) 1.36–1.82 (3.0–4.0)
High activity 0.73–1.00 (1.6–2.2) 0.55–0.68 (1.2–1.5) 1.82–2.73 (4.0–6.0)

What are the side effects of weight-loss medications and how to deal with them

Not everyone’s body or health history is the same. Medications may not work as expected and cause side effects, but you can manage them by referencing this table of common side effects from weight-loss medications.

Side Effect Reason Most Common with Management Strategies
Nausea Many GLP-1 receptor agonists slow gastric emptying, leading to feelings of fullness or queasiness. semaglutide (Ozempic, Wegovy), liraglutide (Saxenda) Eat smaller meals, avoid high-fat foods, take medication with food, and titrate dose slowly.
Diarrhea Medications affecting gut motility or absorption can cause loose stools. orlistat, GLP receptor agonists Increase fiber intake, stay hydrated, monitor diet, and avoid greasy foods.
Constipation Slower gastric motility from medications like GLP-1 agonists may reduce bowel movement frequency. semaglutide, liraglutide Increase fluid intake, eat high-fiber foods, and use stool softeners if necessary.
Headache Pain can result from dehydration, low blood sugar, or medication adjustment. phentermine-topiramate, naltrexone-bupropion Ensure adequate hydration, eat regular meals, and monitor blood pressure.
Insomnia Stimulant medications may increase alertness or disrupt sleep. phentermine, phentermine-topiramate Take medication early in the day, avoid caffeine, and practice good sleep hygiene.
Fatty/oily stools (steatorrhea) Medications can inhibit fat absorption in the intestines. orlistat Reduce dietary fat intake and be near a restroom after meals.
Dizziness This is often related to dehydration, low blood pressure, or low blood sugar. phentermine, naltrexone-bupropion Stay hydrated, rise slowly from sitting/lying, and monitor blood glucose.
Increased heart rate Stimulant effects can activate the sympathetic nervous system. phentermine, phentermine-topiramate Monitor pulse, avoid other stimulants, and report persistent symptoms to provider.
Mood changes (irritability, anxiety) Some medications affect neurotransmitter levels. naltrexone-bupropion Monitor mental health and report severe symptoms; may need a dose adjustment.

Checking out helpful additions and alternatives to weight-loss medication

Some strategies make a real difference. Many of the following, such as diet type, exercise, and supplements, are excellent additions to enhance your weight-loss strategy, or they may serve as helpful alternatives:

  • Bariatric surgery is the most effective non-medication option and leads to about 20–30% total body weight loss.
  • Endoscopic procedures are non-surgical options that typically lead to about 10–20% total body weight loss.
  • Behavioral therapy focuses on changing habits and thinking patterns and leads to about 5–8% total body weight loss.
  • The Mediterranean diet emphasizes plant-forward eating and healthy fats and leads to about 5–10% total body weight loss.
  • A high-protein, moderate-carbohydrate diet supports fullness and muscle preservation and leads to about 3–5% total body weight loss.
  • Exercise alone leads to about 2–5% total body weight loss and is critical for keeping weight off long term.
  • Fiber supplements increase fullness and can lead to about 2–3% total body weight loss.
  • Green tea extract provides a mild metabolic boost and leads to about 1–3% total body weight loss.
  • Probiotics can slightly affect gut bacteria and lead to about 1–3% total body weight loss.
  • Berberine may improve insulin sensitivity and leads to about 1–2% total body weight loss.

About This Article

This article is from the book: 

About the book author:

Patrick Reeves, MD, FAAP, DABOM is a board-certified obesity medicine physician and gastroenterologist. He has spent the last decade studying the detrimental effects of poor nutrition on long term health outcomes in adults, adolescents and young adults. He oversees one of the world’s largest multidisciplinary obesity medicine centers from San Antonio, Texas. Patrick has a strong research pedigree with nearly 50 peer-reviewed publications.

Tania Elliott, MD FAAAAI, FACAAI is a dual board-certified physician, wellness strategist, and nationally recognized health leader with over 15 years of experience. Her comprehensive, root-cause weight loss programs address the whole person and result in sustainable results. Dr. Elliott also serves on national boards, is a Clinical Instructor at NYU Langone Health, and is a trusted medical contributor to Good Morning America, Today, CBS mornings, and Fox News. She has over 600K followers,200M+ views, and 4M+ monthly impressions across platforms.