New Systematic Review Unveils the Best Way To Lose Weight

Systematic reviews from 2020 to 2024 indicate that bariatric surgery provides the most sustained and substantial weight loss compared to other treatments, maintaining about 25% weight loss for up to 10 years. Despite significant benefits, bariatric surgery is still underused in treating severe obesity.

Systematic reviews of scientific data reveal significant differences in weight-loss outcomes among various methods.

Systematic reviews of medical literature from 2020 to 2024 indicate that bariatric surgery, also referred to as metabolic or weight-loss surgery, results in the most significant and enduring weight loss compared to treatments with GLP-1 receptor agonists and lifestyle changes. These findings were presented at the 2024 Annual Scientific Meeting of the American Society for Metabolic and Bariatric Surgery (ASMBS).

Researchers found lifestyle interventions such as diet and exercise resulted in an average weight loss of 7.4% but that weight was generally regained within 4.1 years. GLP-1s and metabolic and bariatric surgery proved far superior. Studies included thousands of patients from clinical studies and several randomized clinical trials.

Five months of weekly injections of GLP-1 semaglutide resulted in 10.6% weight loss and nine months of tirzepatide produced 21.1% weight loss. However, once treatment stopped, about half the lost weight returned within a year despite which drug was used. If injections were continued, tirzepatide patients plateaued at 22.5% weight loss at 17-18 months. Patients on semaglutide plateaued at 14.9% during the same time period.

Semaglutide

Semaglutide is a medication used for managing type 2 diabetes and obesity. It belongs to the class of drugs known as GLP-1 receptor agonists, which mimic the action of the natural hormone glucagon-like peptide-1, important for blood sugar regulation and appetite control. Semaglutide helps lower blood sugar by increasing insulin release, decreasing glucagon secretion, and slowing stomach emptying. Additionally, it reduces appetite, aiding in weight loss when used for obesity. Administered by injection, it is available under brand names such as Ozempic for diabetes and Wegovy for obesity. Common side effects include gastrointestinal discomfort.

Metabolic and bariatric surgery procedures gastric bypass and sleeve gastrectomy demonstrated total weight loss of 31.9% and 29.5% one year after surgery, respectively. Weight loss of approximately 25% was maintained for up to 10 years after surgery.

“Metabolic and bariatric surgery remains the most effective and durable treatment for severe obesity. Unfortunately, it also remains among the most underutilized,” said study co-author and bariatric surgeon Marina Kurian MD, NYU Langone Health. “Surgery needs to play a bigger role in obesity treatment and be considered earlier in the disease process. It is no longer a treatment of last resort and should not be withheld until more severe disease develops. There is no medical reason for this.”

Tirzepatide

Tirzepatide is a novel medication used in the treatment of type 2 diabetes and, recently, obesity. It is a dual GLP-1 and GIP receptor agonist, meaning it targets both the glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide receptors, which play key roles in insulin secretion and blood sugar control. This dual action not only enhances the body’s natural ability to regulate blood sugar levels but also helps suppress appetite and promote weight loss. Administered via injection, tirzepatide has shown significant efficacy in improving glycemic control and reducing body weight, offering a promising option for patients with type 2 diabetes or obesity. Like other drugs in its class, it may cause gastrointestinal side effects such as nausea and diarrhea.

The ASMBS reports that in 2022 nearly 280,000 metabolic and bariatric procedures were performed in the U.S., which represents only about 1% of those who meet eligibility requirements based on BMI. According to the U.S. Centers for Disease Control and Prevention (CDC), obesity affects 42.4% of Americans. Studies show the disease can weaken or impair the body’s immune system and cause chronic inflammation and increase the risk of many other diseases and conditions including cardiovascular disease, stroke, type 2 diabetes, and certain cancers.

“While the new drug treatments show great promise and will lead to more people being successfully treated, particularly if prices come down and insurance coverage improves, we are barely using the best tool we have to fight obesity — metabolic and bariatric surgery, which is safer and more effective than ever before,” said Ann Rogers, MD, ASMBS President-elect and Professor of Surgery at Penn State College of Medicine, who was not involved in the study. “For many people, the risk of death from obesity, diabetes, and heart disease exceeds the risks of surgery.”

Study Methodology

The study included a systematic review of studies that examined weight loss through lifestyle modification, GLP-1s (Semaglutide or tirzepatide), or metabolic and bariatric surgery. GLP-1 data included four randomized clinical trials conducted between 2021 and 2024 while conclusions on lifestyle modifications were based on a systematic review of eight studies. Metabolic and bariatric surgery (gastric bypass and sleeve gastrectomy) were subject to a review of 35 studies, including two randomized clinical trials. In all, researchers reviewed the weight-loss results of approximately 20,000 patients.

Reference: “Effectiveness and Durability of Common Weight Loss Methods” by Megan E Jenkins, Juliane Hafermann, Christine Fielding, Gerhard Prager and Marina Kurian, 11 June 2024, American Society for Metabolic and Bariatric Surgery (ASMBS) 2024 Annual Scientific Meeting.