Unintended Consequences of Weight Loss: A Researcher Weighs In

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Featured article in the August, 2016 Issue of Nutrition Research Update; written by Christian Wright, Doctoral Candidate, Department of Nutrition Science Laboratory of Nutrition, Fitness, and Aging Purdue University

It goes without saying that our nation currently faces a serious obesity crisis. Nearly half of the United States has an obesity prevalence greater than 30% and not a single state in the U.S. shows a prevalence less than 20% (Fig. 1). This pervasiveness of obesity has led to a dramatic spike in cardiovascular disease and type II diabetes cases, which has ultimately decreased the quality of life and life expectancy for many Americans (1). One solution to this nationwide problem is weight loss, particularly diet-induced weight loss (2). Even a 5% reduction in body weight is shown to improve fasting blood lipid and glucose concentrations while decreasing the risk of all-cause mortality (3, 4). Indeed, weight loss is beneficial and is needed to combat our on-going battle with obesity. However, the loss of body mass without considering changes in body composition is irresponsible. Though beneficial for metabolic health, weight loss is shown to decrease bone mass (5) which could, in turn, increase the risk of osteoporosis and skeletal fracture.

Bone is a metabolically active organ serving many functional roles in the body including mechanical support and protection of vital organs, both of which are heavily influenced by bone mass. Bone mineral density (BMD) is a clinical measurement of bone mass and is closely tied to total body mass (6). Many factors contribute to this close relationship, however, it is the mechanical load placed on bone via body mass, particularly lean mass (7), that induces bone formation and closely ties these two together (8). Weight loss reduces this mechanical load place on bone and encourages the loss of BMD (9). This is particularly detrimental in overweight/obese older adults (10) who inherently have lower bone mass and less lean mass (11).

In order to reduce the negative complications of weight loss, dietary strategies that preserve both bone and lean mass should be prioritized, particularly in older adults. Moderately high-protein (1.0 to 1.2 g protein/kg/day or 22% to 29% of total energy consumed) to high-protein (>1.2 g protein/kg/day or >30% of total energy consumed) weight loss diets are shown to beneficially affect soft tissue by preferentially decreasing fat mass while preserving lean mass (12). Can a high protein weight loss diet (HPWL) also preserve bone mass?

Evidence from randomized controlled trials suggest that a HPWL can indeed maintain bone mass if not attenuate weight-loss induced bone loss. Thorpe MP and colleagues showed that a one year HPWL (1.4 g protein/kg/day) maintained total body BMD in obese middle-aged adults (N=130, 45-48 years, ~31 BMI) versus a normal protein diet (0.8 g protein/kg/day) (Fig. 2) (13). Additionally, following a one-year study in post-menopausal women (58.0 ± 4.4 years; BMI 32.1 ± 4.6 kg/m2), Sukumar D and colleagues showed that a HPWL (24% energy from protein) attenuated decreases in BMD and showed lower markers of bone resorption (Fig. 3)(14).

Widely used for their desirable weight-loss and health-related outcomes, recent evidence suggests that HPWL could help preserve bone mass during weight loss and prevent the increased risk of osteoporosis and skeletal fracture. Increasing the consumption of protein-rich foods such as low-fat dairy, lean meats, and/or eggs during energy restriction not only provides a high quality source of dietary protein but bioactives potentially beneficial for bone (15). When advocating weight loss, clinicians must consider the appropriate dietary strategy to optimize all health-related outcomes.



1. Organization WH. Internet: http://www.who.int/mediacentre/factsheets/fs311/en/.
2. Lavie CJ, Milani RV, Ventura HO. Obesity and Cardiovascular Disease Risk Factor, Paradox, and Impact of Weight Loss. J Am Coll Cardiol 2009;53(21):1925-32. doi: DOI 10.1016/j.jacc.2008.12.068.
3. Peeters A, Barendregt JJ, Willekens F, Mackenbach JP, Al Mamun A, Bonneux L, Nedcom tNE, Demography Compression of Morbidity Research G. Obesity in adulthood and its consequences for life expectancy: a life-table analysis. Ann Intern Med 2003;138(1):24-32.
4. Williamson DF, Pamuk E, Thun M, Flanders D, Byers T, Heath C. Prospective study of intentional weight loss and mortality in never-smoking overweight US white women aged 40-64 years. American journal of epidemiology 1995;141(12):1128-41.
5. Pritchard JE, Nowson CA, Wark JD. Bone loss accompanying diet-induced or exercise-induced weight loss: A randomised controlled study. Int J Obesity 1996;20(6):513-20.
6. Villareal DT, Apovian CM, Kushner RF, Klein S, American Society for N, Naaso TOS. Obesity in older adults: technical review and position statement of the American Society for Nutrition and NAASO, The Obesity Society. The American journal of clinical nutrition 2005;82(5):923-34.
7. Salamone LM, Glynn N, Black D, Epstein RS, Palermo L, Meilahn E, Kuller LH, Cauley JA. Body composition and bone mineral density in premenopausal and early perimenopausal women. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 1995;10(11):1762-8. doi: 10.1002/jbmr.5650101120.
8. Shapses SA, Sukumar D. Bone metabolism in obesity and weight loss. Annual review of nutrition 2012;32:287-309. doi: 10.1146/annurev.nutr.012809.104655.
9. Shapses SA, Riedt CS. Bone, body weight, and weight reduction: what are the concerns? The Journal of nutrition 2006;136(6):1453-6.
10. Ensrud KE, Fullman RL, Barrett-Connor E, Cauley JA, Stefanick ML, Fink HA, Lewis CE, Orwoll E, Osteoporotic Fractures in Men Study Research G. Voluntary weight reduction in older men increases hip bone loss: the osteoporotic fractures in men study. The Journal of clinical endocrinology and metabolism 2005;90(4):1998-2004. doi: 10.1210/jc.2004-1805.
11. Elmadfa I, Meyer AL. Body composition, changing physiological functions and nutrient requirements of the elderly. Ann Nutr Metab 2008;52:2-5. doi: 10.1159/000115339.
12. Leidy HJ, Carnell NS, Mattes RD, Campbell WW. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obesity 2007;15(2):421-9. doi: Doi 10.1038/Oby.2007.531.
13. Thorpe MP, Jacobson EH, Layman DK, He XM, Kris-Etherton PM, Evans EM. A diet high in protein, dairy, and calcium attenuates bone loss over twelve months of weight loss and maintenance relative to a conventional high-carbohydrate diet in adults. Journal of Nutrition 2008;138(6):1096-100.
14. Sukumar D, Ambia-Sobhan H, Zurfluh R, Schlussel Y, Stahl TJ, Gordon CL, Shapses SA. Areal and Volumetric Bone Mineral Density and Geometry at Two Levels of Protein Intake During Caloric Restriction: A Randomized, Controlled Trial. J Bone Miner Res 2011;26(6):1339-48. doi: Doi 10.1002/Jbmr.318.
15. Heaney RP, Layman DK. Amount and type of protein influences bone health. The American journal of clinical nutrition 2008;87(5):1567s-70s.