GLP-3s, Monthly Pens: Next Obesity Drugs Leap in 2026

GLP-1 drugs for weight loss, often called "skinny pens," have surged in popularity worldwide, including India. These injectables shift obesity treatment from willpower to biology by mimicking gut hormones.

How GLP-1 Drugs Work

GLP-1 (glucagon-like peptide-1) medications regulate blood sugar, suppress appetite, and slow gastric emptying, leading to substantial weight loss. Dual-agonists like tirzepatide (Mounjaro) target both GLP-1 and GIP hormones for superior results.

The Next Frontier: GLP-3 Drugs Like Retatrutide

Focus now shifts to GLP-3s, especially retatrutide, potentially launching later this year. Eli Lilly completed phase 3 trials, with participants losing up to 28.7% body weight in 48 weeks.

• Semaglutide (Novo Nordisk): ~15% weight loss at 68 weeks
• Tirzepatide: ~22.5% at 72 weeks

"Retatrutide is a molecule on the horizon that looks really exciting," said Delhi-based endocrinologist Dr. Ambrish Mithal.

GLP-1 Launches in India

India saw launches of Mounjaro, Wegovy, and Ozempic (approved for type-2 diabetes, used off-label for obesity) last year, with rapid adoption.

Diabetologist Dr. V. Mohan notes GLP-1 therapies now treat diabetes, obesity, cardiovascular disease, peripheral artery disease, and obstructive sleep apnea. They lower blood glucose, reduce weight and inflammation, and activate tissue receptors.

Expanding Indications and Metabolic Medicine

Newer molecules optimize pharmacokinetics for greater weight loss and target disorders like metabolic liver disease, arthritis, and more. Research explores neurodegenerative diseases, substance-use disorders, type-1 diabetes, inflammatory bowel disease, and even malignancies, per Dr. Daniel Drucker.

"With 60 to 80 compounds under development, this has created the field of metabolic medicine," said Dr. Mohan. Obesity links to over 200 diseases, including cancers.

Disrupting Dosing: Monthly and Oral Options

Lupin licensed bofanglutide from Gan & Lee for once-every-two-weeks or monthly dosing (phase 3 trials ongoing, no approval yet).

"A weight-loss injection that works fortnightly or monthly would generate enormous interest," said Dr. Mithal, head of endocrinology at Max Healthcare.

Novo Nordisk launched oral Wegovy in the US—the first oral GLP-1 for obesity. It pairs with diet and exercise, reduces cardiovascular risks like heart attack and stroke. No India launch date yet, but patients prefer pills.

Muscle Loss Concerns Addressed

Rapid weight loss raises muscle loss fears, but data show neutral or positive effects on muscle and bone. Loss mirrors overall weight reduction, preventable via diet and resistance training.

"Would it be ideal to reduce only fat? Of course—but incredibly hard," said Dr. Mithal. Apps like Shotlee help track GLP-1 doses, diet, and training to preserve muscle.

Personalized GLP-1 Treatment

Semaglutide may offer stronger cardiovascular protection than tirzepatide, leading to individualized prescribing: semaglutide for diabetes/heart disease, tirzepatide for weight loss alone.

"What we're moving toward is horses for courses—different GLP-1s for different patients," said Dr. Mithal. Future trials will test if multi-agonists balance weight loss and heart protection.