Bone mass at risk during weight loss
Overweight Americans are told to lose weight for better health. "Whatever it takes, lose the weight!" So the message goes. Often overlooked, however, is potentially serious bone loss that occurs along with some approaches to weight loss.
In general, overweight and obese people have stronger bones than their lower-weight counterparts of similar age. In fact, obese people generally have about 20 percent more bone mineral content than the average person. Consequently, those carrying some extra weight have less risk of developing osteoporosis and crippling bone fractures of the spine, hip and wrist as they age.
Question: What happens to bones during weight loss?
Answer: It depends on how you lose the weight. A study conducted at the Washington University School of Medicine in St. Louis monitored two groups of people who lost a little more than one pound per month for a year. Half of them lost the weight by eating fewer calories, and the other half lost by increasing their physical activity. Despite the gradual rate of weight loss, the dieters lost bone mineral density from their spines and hips. The exercisers lost weight but not bone mass.
Q: Is it common for bone loss to accompany weight loss?
A: There is growing evidence that bone loss occurs in dieters. Rapid weight loss from cutting calories appears to be the hardest on bones. Some researchers consider this weight loss/bone loss association to be a serious and emerging problem that often follows the increasingly common types of obesity surgery.
Q: How can weight loss be done without bone loss?
A: First, don't aim for a specific goal body weight. Rather, seek to find the stable weight at which you function best -- physically and mentally. If you are physically active, maintaining a stable weight, eating a balanced diet and without other risk factors for chronic diseases, your weight could be right for your genetics -- even if it doesn't get you on the cover of a fashion magazine.
If you really do need to lose weight, do it with bone health in mind. Eat a balanced diet and burn more calories rather than cutting calories too much. Meet all your nutrient needs -- especially calcium and vitamin D. If you need to cut calories in your diet, mainly cut the fat calories, keep protein intake adequate and consider a multivitamin/mineral supplement.
Discuss your concerns about bone loss with your doctor and request an evaluation of your bone density before and during your weight loss so you know how your bones are doing. Don't let a bone fracture be the first sign of osteoporosis.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S. are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dr. Dobbs also works with University Health Services.