Weight-loss drugs such as Ozempic, Wegovy, and Zepbound have helped millions shed pounds and improve metabolic health. However, as these medications become more widespread, potential adverse effects are emerging, particularly concerning bone health.
How GLP-1 Drugs Affect Bones
GLP-1 receptor agonists mimic a hormone that signals the brain to stop eating and slows stomach emptying. This leads to reduced calorie intake, but also reduces intake of bone-boosting nutrients like calcium and vitamin D. When a person loses weight by restricting calories, they lose not only fat and muscle but also dense bone tissue. Additionally, as fat tissue breaks down, the body loses estrogen, a hormone that protects bone. Without it, bones break down faster.
Some studies suggest GLP-1 drugs themselves may increase fracture risk. One study found a 9% higher fracture risk in obese people taking a GLP-1 compared to those not on the drug.
Expert Warnings on Rapid Weight Loss
Dr Daniel Ivankovich, a Chicago-based orthopedic surgeon, told the Daily Mail: 'Typically, when the goal is losing weight, long-term side effects such as loss of bone mass or increasing risk of fractures are not considered. Weight loss patients should be asking about ways to lose weight slowly and preserve bone density.' He cautioned that losing more than two pounds per week can trigger starvation mode, causing the body to break down fat, muscle, and bone. The body pulls calcium from the skeleton to keep vital organs functioning—a process called bone resorption—which outpaces bone rebuilding. Over time, bones become thinner and more prone to fractures.
Nutritional Strategies to Protect Bones
Limiting weight loss to one to two pounds per week gives the skeleton time to adapt. Protein is crucial: it provides building blocks for bone tissue. Experts recommend 1.2 to 1.5 grams of protein per kilogram of body weight daily. For a 200-pound person (91 kg), that means 110 to 135 grams of protein, spread across meals with 30 to 45 grams per meal from eggs, Greek yogurt, chicken, fish, beans, or tofu.
Calcium and vitamin D are also essential. Dr James Chao, a San Diego-based plastic surgeon, advises: 'For bone health aim to get 1,000-1,200 milligrams of calcium per day with 1,000-2,000 IU of vitamin D3 per day. Magnesium and vitamin K2 are important as well.'
Exercise Is Key
Weight-bearing and resistance exercises stimulate bone-forming cells. Activities like walking, jogging, stair climbing, or dancing force the skeleton to work against gravity. High-impact moves like jumping jacks or running generate strong bone-building signals. Resistance training with squats, lunges, and deadlifts strengthens muscles that pull on bones, increasing density. Experts recommend two to three sessions per week.
A randomized clinical trial in Denmark, published in JAMA Network Open, followed 195 adults with obesity. Participants were divided into four groups: exercise alone, liraglutide alone, combination, or placebo. The combination group lost the most weight (37 lbs on average) yet preserved bone density at the hip, spine, and forearm. The liraglutide-alone group lost 30 lbs but showed significant reductions in hip and spine bone density. Exercise alone preserved bone while producing similar weight loss to liraglutide alone. Researchers concluded that combining exercise with GLP-1 treatment is the most effective strategy for significant weight loss while protecting bone health.
