Bone Health & Obesity in Women

Body fat long has been considered to be protective against the fractures commonly associated with osteoporosis because Body Mass Index (BMI) positively correlates to Bone Mineral Density (BMD). However, recent research on this relationship offers compelling evidence to the contrary.

Osteoporosis occurs when the body loses too much bone or fails to make enough bone to replace the loss. This leads to a high risk of bone fracture, often occurring as the result of a fall. Women are at higher risk for osteoporosis, and in the United States, 80 percent of the 10 million people with this bone disease are women. Their risk increases after menopause when hormonal changes affect bone density, so that nearly half of women over the age of 50 will break a bone as the result of osteoporosis.

Older people, especially those with obesity, also are at a high risk for osteoporosis due to loss of bone density, and their risk is compounded because they are more prone to falls due to impaired vision, a decline in fitness, use of certain medications or environmental factors such as loose carpets or poor lighting. Even older adults who have a normal BMI (< 30 kg/m²) but high adiposity ( >35% for women, >25% for men) have been found to have lower muscle and bone strength.

Another reason women are at greater risk is because their bones are smaller and thinner than men’s, and although people with obesity have denser bones, their excess body weight is  disproportionate to bone strength. Further, despite the additional “cushioning” provided by obesity, both obese and non-obese adults have a similar likelihood of experiencing a bone fracture as a result of a fall. Due to mobility issues, people with obesity also may be more likely to fall.

A more recent area of study on bone marrow further contributes to an evolved understanding of obesity as a risk factor for osteoporosis. Studies have found that people with osteoporosis have “higher than normal” levels of Marrow Adipose Tissue (MAT), which has been linked to low bone mass that impacts overall bone health. Bone fragility, which is exacerbated by MAT, further increases with the presence of various conditions including obesity, aging, insulin resistance and type 2 diabetes.

While weight loss is the recommended treatment for obesity, it must be monitored closely in patients with osteoporosis because a lower BMI contributes to reduced bone density. However, moderate caloric reduction, particularly in combination with weight-bearing and muscle loading exercise and resistance training, can provide a range of health improvements while attenuating the loss of bone mass. High calcium and high protein intake also mitigate the decline of bone mass, and a daily calcium and vitamin D supplement should be recommended to women if their diet does not provide enough of these essential nutrients.

The meal replacements used in the New Direction medically-supervised weight management program are high in protein, and participants typically experience consistent, moderate weight loss averaging three pounds per week following slightly higher initial weight loss. Physical activity is also part of the New Direction intensive lifestyle intervention and, using a team approach, exercises appropriate to the specific needs for patients with osteoporosis would be identified to help strengthen muscles and bones. As such, a safe approach to addressing complications of both obesity and osteoporosis could be offered.