In the past, it was believed that heavier people had stronger bones. It was claimed that the bones become denser and stronger to support the excess weight.
And similarly, people with a low body mass index tend to have an increased risk for osteopenia and osteoporosis (bone weakening and bone loss) in old age.
However, more recent findings suggest a more complex relationship between obesity and its effect on the bones. While increased body weight generally increases bone mass density, this does not translate into increased protection and strength.
Obesity appears to damage the bone’s microstructure, compromise the bone quality, and increase the risk for fractures.
The Effects of Different Types of Body Weight
A high body weight related to increased physical activity and muscle mass does not seem to negatively affect bone health as excess adipose tissue (body fat).
Both will increase bone mass density, but excess body fat is significantly more detrimental to bone quality and fracture risk.
Obesity involves alterations of bone-regulating hormones, inflammation, and oxidative stress, affecting bone cell metabolism in ways that muscular weight gain does not.
Obesity is also associated with comorbidities such as osteoarthritis, diabetes, cardiovascular diseases, chronic pulmonary diseases, sleep apnea, and hypertension, predisposing people to neuropathy, weakness, and falls.
Excessive body fat reduces the person’s agility, flexibility, and reaction time, leading to an increased risk for falls and fractures. On the other hand, greater muscle mass can improve balance and coordination and reduce frailty and fall risk.
The Effect of Weight Loss
Due to the many health consequences of obesity, weight loss is strongly recommended for obese individuals.
In the context of bone health and fracture risk, weight loss can seem to have a paradoxical effect. Even though obesity reduces bone quality and increases the risk for fractures, weight loss can also decrease bone mass density and increase bone loss and fracture risk.
This should not discourage people from losing weight, as weight loss benefits for reducing comorbidities and improving general health are much greater than any potential negative effects on bone health.
Nutrient supplementation of calcium, protein, and vitamin D can help to attenuate the bone loss associated with calorie restriction and weight loss.
Exercise training should also be included in the weight loss and weight maintenance process to preserve and even increase bone mass density.
Recommendations for exercise for bone health include:
- Resistance training – at least two days per week
- Impact exercises (jumps, hops, running) – at least four days per week
- Balance and mobility training – at least 2-3 hours per week
Aerobic exercises do not appear to affect your bones significantly but are still generally recommended due to the additional cardiometabolic health benefits.
If you are obese and trying to lose weight, it is essential to maintain a healthy diet while engaging in regular physical activity and exercise. Be sure to speak with your doctor or health care provider about a personalized plan that is right for you.