Will I lose muscle as well as fat on these injections?

Some, yes. In one study of tirzepatide, about three-quarters of the weight lost was fat and about a quarter was lean mass, which means muscle and other tissue that is not fat.

Can exercise help my bones while I lose weight?

Studies suggest it helps. In one trial, people who took liraglutide and also exercised lost the most weight and kept their bone density. The World Health Organization advises strength training on at least 2 days a week, plus about 150 minutes of moderate activity each week.

Patient guide

Losing weight on GLP-1 injections: protecting your bones

Do weight-loss injections weaken bones? What studies show on GLP-1 medicines, bone density, muscle, and how exercise and food fit in. Aggarwal Clinic, Patiala.

GLP-1 medicines are weight-loss injections. This page covers what studies show about these medicines and your bones, and it also covers tirzepatide. It uses generic names only, such as semaglutide, liraglutide and tirzepatide. All the bone studies here come from outside India, from Europe, the US and Israel. The page is for men and women. Where a study was mostly in women past menopause, the page says so.

Aggarwal Clinic does not run a weight-loss service. This page is about bone health for people who are already on these medicines or are thinking about them with their doctor.

Will weight-loss injections weaken my bones?

Studies so far do not clearly show more, or fewer, broken bones with GLP-1 medicines. People who lose a lot of weight on the medicine alone lose a small amount of bone density at the hip and spine. Bone density means how much mineral your bones hold.

Will I lose muscle as well as fat?

Some, yes. In one study of tirzepatide, about three-quarters of the weight lost was fat. About a quarter was lean mass, which means muscle and other tissue that is not fat.

Can exercise protect my bones while I lose weight?

Studies suggest it helps. In one trial, people who took liraglutide and also exercised lost the most weight and kept their bone density. People who took the medicine without exercise lost more bone than people who only exercised.

The World Health Organization advises strength training on at least 2 days a week, plus about 150 minutes of moderate activity each week. Ask your doctor or physiotherapist how to start safely.

I am over 65, or past menopause. Should I worry more?

You may need a bone check first. In a trial of people at higher fracture risk, mostly women past menopause, semaglutide led to a small loss of hip and spine bone density over one year.

One study of adults over 65 with diabetes found 11% more fractures, but other studies disagree.

In older adults who were dieting, the type of exercise mattered for the hip. Hip bone loss was 0.5% to 1% with strength or mixed exercise. It was 3% with aerobic exercise alone, which means exercise such as walking.

What should I eat?

Eat enough protein, and get enough vitamins and minerals. US obesity and nutrition societies advise this for everyone on these medicines. Trials have not yet shown the exact amount of protein needed.

Do I need a vitamin D test?

Not just because of your weight. A 2024 guideline advises against routine vitamin D tests, including in people with obesity. It suggests vitamin D for adults over 75.

Is weight-loss surgery different?

Yes. Studies show a higher chance of fractures after weight-loss surgery, especially after some types of bypass. Studies of GLP-1 medicines have not shown this.

What about newer injections?

Tirzepatide and newer medicines have no studies yet that measure bone density or fractures as the main result.

For doctors

The evidence behind this page is in GLP-1 and obesity drugs and bone and Fracture risk in perimenopause.

Talking to a doctor in Patiala

To talk about your bone health with Dr Aditya Aggarwal, orthopaedic surgeon, call Aggarwal Clinic on +91 98768 24676.

Aggarwal Clinic, 1-E, The Mall, Patiala.

This page is general information, not medical advice. Please talk to your doctor about what is right for you.

Questions

Common questions

Do weight-loss injections weaken bones?: Studies so far do not clearly show more, or fewer, broken bones with GLP-1 medicines. People who lose a lot of weight on the medicine alone lose a small amount of bone density at the hip and spine.
Will I lose muscle as well as fat on these injections?: Some, yes. In one study of tirzepatide, about three-quarters of the weight lost was fat and about a quarter was lean mass, which means muscle and other tissue that is not fat.
Can exercise help my bones while I lose weight?: Studies suggest it helps. In one trial, people who took liraglutide and also exercised lost the most weight and kept their bone density. The World Health Organization advises strength training on at least 2 days a week, plus about 150 minutes of moderate activity each week.
Do I need a vitamin D test because I am overweight?: Not just because of weight. A 2024 guideline advises against routine vitamin D tests, including in people with obesity. It suggests vitamin D for adults over 75.

Last reviewed 18 October 2026

General information only; it doesn’t replace a consultation. In an emergency, call 112.