The rebound problem: weight comes back when you stop
A major long-term trade-off is that the weight loss from GLP-1 drugs is not permanent. A 2025 meta-analysis of 36 studies found that after stopping the medication, patients regain a significant amount of weight. Semaglutide (the drug in Ozempic and Wegovy) had the highest rebound, with users regaining an average of 5.15 kg (about 11.3 pounds) after discontinuation [1]. This means these drugs likely need to be taken indefinitely to maintain the weight loss, turning a short-term treatment into a lifelong commitment — a trade-off many people don't consider when they start.
The same analysis showed that other GLP-1 drugs also led to weight regain, though less dramatically: exenatide users regained about 3.06 kg, and liraglutide users regained about 1.50 kg [1]. The pattern is clear: these drugs suppress appetite and slow digestion, but when you stop, those effects reverse. This isn't a failure of the drug — it's a feature of treating obesity as a chronic condition, but it's a trade-off that needs to be factored into any decision to start therapy.
Serious gastrointestinal risks: more than just nausea
While mild nausea and diarrhea are well-known short-term side effects, the long-term gastrointestinal risks are more serious and less publicized. A 2023 study found that GLP-1 users had a 4.5 times higher risk of intestinal obstruction compared to people taking other diabetes medications, and a separate real-world analysis of over 25,000 patients found a 3.5-fold increase [2]. Intestinal obstruction is a medical emergency where the bowel is blocked, requiring hospitalization and sometimes surgery.
This finding is reinforced by the largest and most comprehensive study in this set — a 2025 analysis of over 215,000 GLP-1 users compared to more than 1.2 million people on other treatments. It confirmed an increased risk of gastrointestinal disorders, along with other issues like hypotension (dangerously low blood pressure), kidney stones, and drug-induced pancreatitis [3]. The same study also found benefits (lower risks of dementia, addiction, and heart problems), but the gastrointestinal risks were consistent and significant across all the major studies here [2][3].
Thyroid cancer signal: a rare but real risk
Perhaps the most concerning long-term trade-off is the link to thyroid cancer. A large French study using national health data (over 2,500 thyroid cancer cases matched with 45,000 controls) found that using GLP-1 drugs for 1-3 years was associated with a 58% increased risk of all thyroid cancers and a 78% increased risk of medullary thyroid cancer specifically [4]. Medullary thyroid cancer is a rarer but more aggressive form. This risk is why these drugs carry a boxed warning about thyroid tumors, but the human data confirming it is relatively recent and not widely known.
It's important to put this in perspective: the absolute risk is still low — the study looked at a large population and found a relative increase. But for someone considering long-term use, especially if they have a family history of thyroid cancer, this is a trade-off that deserves a conversation with their doctor. The 2025 mega-analysis of over 10,000 clinical trials also noted that the long-term effects on organs like the kidneys, heart, and bones have not been thoroughly investigated [5], meaning there may be other trade-offs we don't yet fully understand.
About These Sources
This answer is built on 5 peer-reviewed studies — published from 2022 to 2025, 3 from 2024 or later, 3 in Q1 journals, collectively cited 493 times — selected as the most relevant from 5 studies that passed quality screening, drawn from 56 papers retrieved from a database of over 500 million.
Sources used in this answer
Rebound or Retention: A Meta-Analysis of Weight Regain After the Discontinuation of Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists and Other Anti-obesity Drugs
A meta-analysis of 36 studies found that weight regain after stopping GLP-1 drugs is common and drug-dependent; semaglutide users regained an average of 5.15 kg (11.3 lbs) after discontinuation, the highest among the drugs studied.
A potentially serious adverse effect of GLP-1 receptor agonists
A review of clinical and animal data found that GLP-1 drugs increase the risk of intestinal obstruction by 3.5- to 4.5-fold compared to other diabetes medications, and animal studies showed the drugs can cause significant bowel enlargement.
Mapping the effectiveness and risks of GLP-1 receptor agonists
The largest study here, covering over 215,000 GLP-1 users, systematically mapped 175 health outcomes and confirmed both benefits (reduced dementia, addiction, heart risks) and harms (increased gastrointestinal disorders, hypotension, kidney stones, pancreatitis) compared to usual care.
GLP-1 Receptor Agonists and the Risk of Thyroid Cancer
A nested case-control study using French national health data found that 1-3 years of GLP-1 use was associated with a 58% higher risk of all thyroid cancers and a 78% higher risk of medullary thyroid cancer.
Clinical Data Mega-Collection of Obesity and Obesity-Related Trials: Primary Inclusion Criteria from All Studies and Highlights of Clinical Efficacy Analysis of GLP-1 Drugs
A mega-collection of over 10,000 obesity trials noted that the long-term effects of GLP-1 drugs on organs like the kidneys, heart, bones, and muscle have not been adequately investigated or disclosed, and that rapid weight loss may not always be beneficial for patient quality of life.