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Tippens KM, Purnell JQ, Gregory WL, et al. Expectancy, Self-Efficacy, and Placebo Effect of a Sham Supplement for Weight Loss in Obese Adults. J Evid Based Complementary Altern Med. 2014;19(3):181-188doi: 10.1177/2156587214528513.
Tippens, K. M., Purnell, J. Q., Gregory, W. L., Connelly, E., Hanes, D., Oken, B., & Calabrese, C. (2014). Expectancy, Self-Efficacy, and Placebo Effect of a Sham Supplement for Weight Loss in Obese Adults. Journal of evidence-based complementary & alternative medicine, 19(3), 181-188. https://doi.org/10.1177/2156587214528513
Tippens, Kimberly M, et al. "Expectancy, Self-Efficacy, and Placebo Effect of a Sham Supplement for Weight Loss in Obese Adults." Journal of evidence-based complementary & alternative medicine vol. 19,3 (2014): 181-188. doi: https://doi.org/10.1177/2156587214528513
Tippens KM, Purnell JQ, Gregory WL, Connelly E, Hanes D, Oken B, Calabrese C. Expectancy, Self-Efficacy, and Placebo Effect of a Sham Supplement for Weight Loss in Obese Adults. J Evid Based Complementary Altern Med. 2014 Jul;19(3):181-188. doi: 10.1177/2156587214528513. PMID: 24695007; PMCID: PMC4182347.
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J Evid Based Complementary Altern Med. 2014 Jul;19(3):181-188. doi: 10.1177/2156587214528513.

Expectancy, Self-Efficacy, and Placebo Effect of a Sham Supplement for Weight Loss in Obese Adults.

Journal of evidence-based complementary & alternative medicine

Kimberly M Tippens, Jonathan Q Purnell, William L Gregory, Erin Connelly, Douglas Hanes, Barry Oken, Carlo Calabrese

Affiliations

  1. 1 Helfgott Research Institute, National College of Natural Medicine, Portland, OR, USA.
  2. 2 Oregon Health & Science University, Portland, OR, USA.

PMID: 24695007 PMCID: PMC4182347 DOI: 10.1177/2156587214528513

Abstract

This study examined the role of expectancy in the placebo effect of a sham dietary supplement for weight loss in 114 obese adults with metabolic syndrome. All participants received lifestyle education and were randomized to 1 of 3 conditions: (1) a daily placebo capsule and told that they were taking an active weight loss supplement, (2) daily placebo and told they had a 50% random chance of receiving either the active or placebo, or (3) no capsules. At 12 weeks, weight loss and metabolic outcomes were similar among the 3 groups. Participants in both groups that took capsules showed decreased weight loss self-efficacy and increased expectations of benefit from dietary supplements. Participants not taking capsules showed the opposite. Adverse events were more frequently reported in groups taking capsules than those who were not. These findings suggest that supplements without weight loss effects may have nocebo effects through diminished self-efficacy.

Keywords: expectancy; metabolic syndrome; obesity; placebo; weight loss

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