August
2008
Calorie Restriction and Bone Loss
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Bones Need Care Too
It can seem like a cruel contradiction: lose weight, lose bone mass. Lose a lot of weight and lose even more. (Rest assured there’s more to the story, but we continue….) A collaborative study involving researchers from the University of Kansas and the University of Missouri highlights the downside of weight loss by calorie restriction both during and in the months following weight loss.
Researchers examined protein markers of bone breakdown and formation in 37 obese, middle-aged adults who lost 20 percent of their body weight through a severe calorie-restricted diet. Protein markers, which are released during bone breakdown and formation, are used as indirect indicators of bone remodeling. During the 3-month weight-loss phase, bone remodeling was elevated, and bone formation and breakdown were imbalanced as a result of a low energy intake. After weight loss phase, bone remodeling remained elevated during the 9-month weight maintenance phase, but bone formation and breakdown appeared to be balanced.
via Science Daily
Though the bone breakdown and formation rate had hit a homeostasis, the researchers caution that “Rapid rates of bone remodeling, regardless of the balance of breakdown and formation, can increase bone fragility.” They add that those seeking to lose weight should consider adding weight-bearing exercise and make sure they’re getting adequate calcium.
Our reaction? Well, yeah. Weight-bearing exercise is absolutely essential for maintaining not just muscle mass but bone density. Bone density is not only influenced by how much weight the body senses it carried around but how much “work” the body senses is happening in the bone and muscle connections. Countless studies have confirmed this, and research out of Washington University School of Medicine in St. Louis highlights its “osteoprotective effect” in weight loss. Their study compared bone density (as measured by blood markers and dual-energy x-ray absorptiometry) in two groups of older adults, one of which lost weight through restricting calories and the other by exercise. Their results? Though the CR group lost some 2.2 % of bone density in fracture-prone areas like the lower spine, pelvis and femur, the exercise group showed no substantial change in bone density. Though both groups showed higher rates of bone turnover than the control group, the researchers indicated that the work of exercise, the “muscles pulling on bones” can “produce strains in the skeleton that stimulate new bone production.” The “exercise-induced mechanical strain,” they say is actually healthy and protective.
The Primal Blueprint isn’t about caloric restriction. Interestingly though, when people cut out the carbs, they’re surprised how much their calorie intake drops. (The same is true for lab animals: caloric restriction diets generally reduce carb calories more than any other macronutrient.) But it’s ultimately about how your diet complements your body’s natural functioning. As Mark has said in the past, the “success” of CR in weight loss probably has more to do with insulin mitigation than with sheer calorie reduction. Add to this picture an exercise routine that challenges the body’s physical structure and fitness in a natural, optimal way, and you’re going to see optimal health. And wouldn’t you know it? That includes bone health.
Thoughts? We’d love to hear your questions or additions to what these studies highlight.
Wow, nice find! I knew that extreme weight loss (trying to lose 5 pounds in a week, for example) was dangerous, but I didn’t know that weight loss with LACK of weightlifting was dangerous. I’m glad I do my cardio and weightlifting at the same time.
Eating fewer calories than your body “wants” causes all organs to starve in addition to fat and bone tissue. If your metabolic profile is such that you body “wants” to have a certain bodyfat percentage, it will fight to maintain that at the expense of your other tissues. The reason traditional dieting is so difficult is that your organs are starving.
The only way around it is to change your metabolic profile through a good diet and exercise. Weight loss through grain avoidance, carb restriction, and intense exercise can cause fat loss without starving your organs.
this is interesting to me:
the “success” of CR in weight loss probably has more to do with insulin mitigation than with sheer calorie reduction.
as Id say I DO NOT do CR but I do focus on insulin mitigation (who knew? I mean I did it for how I feel (more energetic. less moody/bloated) but didnt use those 2 words) yet eat as much as I want of protein and goodfat rich foods.
Great post, but I’ve been seeing research that it isn’t low calcium intake that affects the bones, as much as low blood vitamin D3 levels that keep the body from being able to use the calcium it gets.
Perhaps bone loss won’t happen under caloric restriction/intermittent fasting if D3 is adequately supplemented? (And apparently the RDA is ridiculously low — many people need 5000 IU of D3 a DAY to get to a blood level of 50.)
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