Obesity is a major concern among older adults, but intentional weight loss can sometimes result in unwanted bone and muscle loss. Because these changes increase the risk of frailty and fractures, researchers are exploring whether exercise can help protect bone mineral density (BMD) during dieting.
So, can exercise support bone health while older adults lose weight?
Why Weight Loss Can Lead to Bone and Muscle Loss
Ageing naturally brings declines in strength, mobility and bone density. When paired with obesity, these age-related changes can significantly impact daily functioning. While losing excess weight offers important health benefits, it may also accelerate losses in bone mass and muscle tissue — both critical for maintaining independence and reducing fall risk.
One potential solution is pairing weight loss with structured exercise. But which type is best for preserving bone density — aerobic exercise, resistance training or a combination of both?
How the Study Was Conducted
To answer this question, researchers performed a 26-week randomised controlled trial involving obese older adults undertaking a weight-loss program.
A total of 141 participants completed the study. All were aged 65 or older, had a BMI of 30 or above, lived sedentary lifestyles and had stable body weight and medication levels over the previous year. Participants also displayed mild to moderate frailty.
Exclusion Criteria
- Severe heart disease
- Physical impairments preventing exercise
- Dementia
- Very low BMD at the spine or hip
- Use of bone-affecting medication within the last year
Participants were randomly assigned to one of four groups:
- Aerobic training + weight-management program
- Resistance training + weight-management program
- Combined aerobic + resistance training + weight-management program
- Control group — attended monthly healthy-eating education sessions only
Weight-Management Program
Participants in the three intervention groups followed a diet plan designed to create a 500–750 kcal daily deficit. Weekly sessions with a dietitian supported behaviour change and nutrition adjustments. The intended outcome was 10% weight loss within six months.
Exercise Training Protocols
Aerobic training (60 minutes, 3x weekly) included treadmill walking, cycling and stair climbing, with intensity progressing from 65% to 85% of peak heart rate.
Resistance training (60 minutes, 3x weekly) involved upper- and lower-body machine exercises plus balance work.
Combined training (75–90 minutes, 3x weekly) incorporated both aerobic and resistance exercises.
All participants received supplements to reach daily intakes of 1500 mg calcium and 1000 IU vitamin D.
What the Study Found
All three exercise groups experienced meaningful reductions in body weight and fat mass compared with the control group.
The type of exercise played an important role in bone and muscle preservation:
BMD and Lean Muscle Changes
- Resistance and combined exercise groups saw significantly less loss of BMD and lean body mass.
- The aerobic-only group experienced the greatest reductions in bone density.
Bone Turnover Markers
Markers such as serum C-telopeptide, procollagen type 1 N-propeptide and osteocalcin increased most in the aerobic group, indicating higher levels of bone breakdown.
Conclusion: Which Exercise Protects Bone Best?
Researchers concluded that resistance training and combined training are more effective than aerobic exercise alone in preventing losses in bone mineral density, lean mass and bone integrity during weight loss. For older adults trying to lose weight safely, these forms of exercise offer the strongest protective benefits.
Study Limitations
- Bone quality was not measured, meaning structural improvements may have gone undetected.
- The 26-week duration was not long enough to evaluate long-term outcomes such as fractures or fall risk.
- More research is needed to explore sex-specific responses and longer-term effects on bone health.
Future long-term studies may help identify the most effective exercise strategies to support bone and muscle health during weight loss in older adults.
