Weight loss has effect on bone density

Dear Dr. Roach: Over the past year of pandemic lockdown, I have worked hard at reducing calories to lose weight and increasing my exercise on an elliptical trainer. I am 5 feet, 7 inches tall and age 70. I went from 202 pounds to 149.3. My weight goal is 145. My waistline is 25.5 inches. I have achieved a size 14 in clothing, which is what I wore in 2002. According to my digital scale, my BMI is now 23.4, and according to the BMI chart, I am now in the good “healthy weight” range.

Also, in May 2019 I had total knee replacement surgery and believe that reducing my weight would be beneficial to my hips, knees, ankles and feet. Because of my continued physical therapy exercise, as well as losing the extra pounds, I feel steadier on my feet than I have felt in years.

I recently read that “older adults have a [BMI] of between 25 and 27, not under 25,” or they run the risk of osteoporosis. My last bone density scan showed that I had significant improvement of my bone density, and I would think that with all this walking on the elliptical trainer (30-60 minutes daily), it will prove to be at least as good. In addition, I do some exercises with small hand weights. I have no reason to think I am amongst the 24% of “older” women who have osteoporosis of the spine, etc.

Should I be content with a weight of 149? Should I gain back some fat?

P.R.

Answer: I think healthy diet and regular exercise are much more important than the weight or BMI, at least for people who are not very obese. It is true that carrying some extra weight protects to some extent against osteoporosis, and very thin women are at higher risk. However, I am so impressed with your activity and accomplishments over the past year that I would recommend you continue your exercise and let your weight stay where it is. You should continue to get bone density scans as recommended, but you are quite right that regular weight-bearing exercise is particularly good at maintaining bone health, along with a diet including adequate calcium and ensuring good vitamin D if you are at risk for low vitamin D.