Understanding GLP-1 Drugs: Their Role in Weight Loss

16 March 2024 2021
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In the wake of numerous media headlines and TikTok 'before-and-afters,' it's hard not to have some curiosity about Ozempic. Many people are questioning whether it's a miraculous medication ushers in a healthier era, or just another pharmaceutical stopgap solution. To clarify things, let's start with some basic science. 

Ozempic is classified as a glucagon-like peptide-1 (GLP-1) agonist, a type of drug that simulates GLP-1, an incretin hormone naturally created in the gut every time you consume food. GLP-1 motivates insulin production, assists in managing blood glucose levels, and reduces the speed of food passage from your stomach to the small intestine, keeping you satiated for a longer period. 

While high fiber and protein foods can naturally enhance GLP-1, drugs like Ozempic provide similar advantages in the form of a weekly injection administered at home (or less frequently, as a daily tablet). 

'GLP-1 also communicates to the brain about the presence of fluid in the gastrointestinal tract, leading to a feeling of fullness and cessation of eating,' delineates Judith Korner, MD, director of the Metabolic and Weight Control Center at NewYork-Presbyterian/Columbia University Irving Medical Center. She adds that the threshold for these signals varies among individuals - some might feel full after a single slice of pizza, while others might not experience that sensation until they've eaten several slices. 

With insights from Dr. Korner, we have delved deeper into the effectiveness of GLP-1s for weight loss, possible beneficiaries, and the potential risks and side effects of these drugs. 

It's likely you already know that GLP-1s were initially developed for diabetes treatment, but patients later reported a beneficial side-effect - a significant reduction in hunger. Interestingly, some individuals noted that the drug helped suppress their overt thoughts about eating, thereby making healthier food choices easier. 

According to one study, participants using GLP-1s recorded a weight loss ranging from about 10.5 to 15.8 pounds. Another research paired medication with healthier lifestyle adaptations and found that participants averaged a weight loss of 33.7 pounds, in contrast to merely 5.7 pounds lost by the group who relied solely on diet and exercise. 

Currently, only two GLP-1s (Wegovy and Saxenda) are approved for weight loss. Dr. Korner explains that Wegovy and Ozempic share the same active ingredient, semaglutide, but are marketed under different brand names depending on whether they’re prescribed for diabetes treatment (Ozempic) or weight loss (Wegovy). 

Saxenda (used for weight loss) and Victoza (used to treat diabetes) also follows the same pattern, both utilizing the GLP-1 agonist liraglutide. Zepbound, a brand using the active ingredient tirzepatide, was approved for weight loss in November 2023. This drug, which is technically a dual agonist, uses two types of incretin hormones—GLP-1 and GIP. Mounjaro is the diabetes equivalent of Zepbound.

Dr. Korner usually advises her patients to prioritize lifestyle changes. However, she notes that diet and physical exercise are often insufficient on their own.

To determine whether an individual is suitable for GLP-1 therapy, medical guidelines recommend considering their Body Mass Index (BMI). Persons with a BMI of 30 or above could potentially benefit from using GLP-1s to manage their weight.

'If an individual has health issues likely brought on or worsened by increased body fat, such as hypertension, sleep apnea, or diabetes, we utilize a BMI of 27 and above as the criteria,' adds Dr. Korner.

Generally, GLP-1s are not only safe for weight loss but also highly effective. Clinical trials have additionally revealed other potential benefits of GLP-1s, like improvements in metabolic parameters such as blood sugar control, blood pressure, and cholesterol levels.

However, Dr. Korner cautions that individuals with medullary thyroid cancer (a rare form of thyroid cancer), multiple endocrine neoplasia (an excessive growth of tumors on the endocrine glands), pancreatitis, or gallbladder issues should abstain from the medication.

The most commonly reported side-effects of GLP-1s according to Dr. Korner, include gastrointestinal issues like nausea, vomiting, diarrhea, or constipation. Fatigue, headaches, and gallstones (identified by abdominal pain) are less common side-effects.

Furthermore, some initial research suggests that GLP-1s may potentially cause small bowel obstruction, as noted in several observational studies. One study even reported that people with diabetes were 4.5 times more likely to experience an obstruction with GLP-1s compared to other glucose medications.

If you’re taking GLP-1s and experience any of the above, tell your provider. They may suggest altering your dosage or discontinuing the medication indefinitely. 

There’s no denying that GLP-1s are incredibly effective at treating diabetes and contributing to weight loss. With more than 40 percent of the U.S. adult population classified as clinically obese and more than 11 percent diagnosed with type 2 diabetes, these drugs can be life changing for millions of people—especially when paired with sustainable lifestyle improvements.

“These medications always work better if used in conjunction with lifestyle changes and healthy diet,” says Dr. Korner. She also stressed the need to mitigate muscle loss during the weight loss process with regular strength training.