Weight-loss drugs like Ozempic, Wegovy and Zepbound have benefitted millions of consumers by helping them shed pounds and become more metabolically healthy.
But as more time passes since their explosive entry into the weight-loss market, possible adverse or downstream effects become clearer.
Groundbreaking GLP-1 drugs mimic a hormone in the body that signals to the brain when to stop eating while slowing stomach emptying. This results in fewer calories — and fewer bone-boosting nutrients — taken in during the day.
When a person loses weight by restricting calories, they lose more than just fat and muscle tissue; they also lose crucial dense bone tissue.
And as fat tissue breaks down, the body loses valuable stores of the hormone estrogen, which protects bone. Without it, bones break down faster.
Given the number of GLP-1 patients experiencing bone density issues, though, the possibility that the drugs themselves can be the cause is being considered.
One study in obese people taking a GLP-1 found a nine percent increased fracture risk compared to people not on the drug.
‘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,’ Dr Daniel Ivankovich, a Chicago-based orthopedic surgeon, told the Daily Mail. ‘Weight loss patients should be asking about ways to lose weight slowly and preserve bone density.’
When weight drops too fast, more than two pounds per week, the body enters starvation mode, breaking down fat, muscle, and bone. It pulls calcium from the skeleton faster than bone can rebuild (stock)
He cautioned against rapid weight loss, which can happen with GLP-1 medications.
When pounds drop too fast — more than two pounds per week — the body goes into starvation mode and begins breaking down not just fat but also muscle and bone.
Specifically, the body begins to pull calcium from the skeleton to keep vital organs functioning. This process, called bone resorption, outpaces the body’s ability to rebuild new bone.
Over time, bones become thinner, weaker and more prone to fractures. \For people taking GLP-1 medications, this is a particular concern because these drugs can cause very rapid weight loss.
Limiting weight loss to one to two pounds per week gives the skeleton time to adapt and maintain its density.
And protein is nonnegotiable, Ivankovich said. It provides the building blocks for bone tissue.
Without adequate protein, the body cannot produce enough collagen matrix, which is the flexible framework that gives bones their strength and resilience.
Spreading protein across all meals ensures a steady supply throughout the day rather than a single spike.
To keep bones strong while losing weight, experts recommend consuming 1.2 to 1.5 grams of protein per kilogram of body weight each day. For a 200-pound person, about 91 kilograms, that means roughly 110 to 135 grams of protein daily.
Spread that across three meals with roughly 30 to 45 grams per meal by including foods like eggs, Greek yogurt, chicken, fish, beans or tofu.
This steady intake gives the body the building blocks it needs to maintain bone structure even as calories are cut.
Eating too little protein signals the body to break down not just fat but also bone and muscle, which is exactly what weight-loss medication users want to avoid.
‘Loss of mobility or flexibility such as having trouble walking, bending, or squatting are signs of bone loss,’ Ivankovich said.
‘Losing strength in the hands or legs is another symptom, along with fractured or broken bones after minor falls.’
When a person loses weight on GLP-1 medications, they also lose access to critical bone-supporting nutrients, including calcium and vitamin D.
These nutrients are the raw materials that bones need to maintain their density and structural integrity.
Without sufficient calcium, the body begins to draw calcium from the skeleton directly to support essential functions like nerve signaling and muscle contraction, causing bone resorption.
Vitamin D deficiency further compounds the problem by limiting calcium absorption from what little food is eaten.
Over months of rapid weight loss, a person can shed pounds while silently thinning their bones, increasing fracture risk from minor falls or even everyday movements.
Most people forget that rapid weight loss can thin bones and raise fracture risk, Dr. Daniel Ivankovich, a Chicago orthopedic surgeon, told the Daily Mail
Some people on GLP-1 can benefit from supplements to prevent these deficiencies.
Dr James Chao, a San Diego-based plastic surgeon, told the Daily Mail: ‘For bone health aim to get 1,000-1,200 milligrams of calcium per day with 1,000-2,000 [international units] of vitamin D3 per day.
‘Magnesium and vitamin K2 are important as well but I’ll let you speak with your doctor about supplementation.’
For patients taking GLP-1 medications, adding exercise is also essential.
Not all exercise is equal when it comes to bone health, however. Weight-bearing and resistance exercises are the most effective because they force the skeleton to work against gravity, stimulating bone-forming cells called osteoblasts to build new tissue.
These can include walking, jogging, climbing stairs, or dancing – anything where the feet and legs support the body’s full weight.
High-impact activities like jumping jacks, skipping rope or running generate the strongest bone-building signal. For people who cannot do high-impact moves, brisk walking on an incline or stair climbing still provides meaningful benefit.
Resistance training adds another layer of protection by strengthening the muscles that pull on bones, which in turn triggers bone density increases.
Recommended moves include squats, lunges, deadlifts and overhead presses using free weights, resistance bands or weight machines.
Experts suggest aiming for two to three sessions per week, focusing on major muscle groups and progressively increasing the weight over time.
This graph shows bone density changes at the hip before, during and after the low-calorie diet (shaded area) and one year of treatment. The exercise + liraglutide group (blue triangle) preserved hip bone density. The liraglutide-alone group (dark blue diamond) lost significantly more hip bone density than both the exercise (yellow square) and placebo groups (gray circle)
This graph shows bone density changes in the lower spine before, during, and after the low-calorie diet (shaded area) and one year of treatment. The combination group preserved spine bone density. The liraglutide-alone group lost significantly more spine bone density than both the exercise and placebo groups
For patients on GLP-1 medications who are losing weight rapidly, combining weight-bearing cardio with strength training is particularly important. Without these mechanical stresses, the body has little incentive to preserve bone mass, and density can decline even faster than fat.
A randomized clinical trial conducted in Denmark and published in JAMA Network Open sought to answer whether exercise, the GLP-1 medication liraglutide or both together can preserve bone density during weight loss.
Researchers followed 195 adults with obesity, with an average age of 43, for the one-year study following an initial eight-week low-calorie diet. Participants were divided into four groups: exercise alone, liraglutide alone, a combination of both or placebo.
The combination group lost the most weight, dropping an average of 16.9 kilograms, or about 37lbs. The liraglutide-alone group lost 30lbs (13.7kg), the exercise-alone group lost 24.6lbs (11.2kg) and the placebo group lost 15lbs (7kg).
Despite the combination group’s larger weight loss, this group preserved bone mineral density at the hip, spine and forearm.
Meanwhile, the liraglutide-alone group showed significant reductions in hip and spine bone density compared with both the placebo and exercise-alone groups.
Exercise alone produced similar weight loss to liraglutide alone but preserved bone rather than reducing it.
The researchers concluded that combining exercise with GLP-1 treatment is the most effective strategy for losing a significant amount of weight while protecting bone health.
