Impact of protein supplementation after bariatric surgery: A randomized controlled double-blind pilot study

Nutrition. 2016 Feb;32(2):186-92. doi: 10.1016/j.nut.2015.08.005. Epub 2015 Sep 1.


Objectives: Bariatric patients are at risk of protein deficiency. The aim of this study was to determine possible benefits of postoperative protein supplementation weight reduction, body composition, and protein status.

Methods: Twenty obese patients who underwent bariatric surgery were randomized either to the protein (PRO) group, which received a daily protein supplement over 6 months postoperatively, or to the control (CON) group, which received an isocaloric placebo in a double-blind fashion. Data on protein and energy intake, body weight, body composition, blood proteins, and grip force was collected preinterventionally and at 1, 3, and 6 months postoperatively.

Results: In both groups body weight was significantly reduced to a similar extent (after 6 months: PRO group 25.4 ± 7.2%, CON group 20.9 ± 3.9%; intergroup comparison P > 0.05). Protein intake was steadily increased in the PRO group, but not in the CON group, and reached maximum at month 6 (25.4 ± 3.7% of energy intake versus 15.8 ± 4.4%; P < 0.001). In the PRO group, body fat mass loss was higher than that in the CON group (79% of absolute weight loss versus 73%; P = 0.02) while lean body mass loss was less pronounced (21% versus 27%, P = 0.05). Blood proteins and grip force did not differ at any time point between the two groups.

Conclusions: The present study suggests that protein supplementation after bariatric surgery improves body composition by enhancing loss of body fat mass and reducing loss of lean body mass within the 6 months follow up.

Keywords: Body composition; Body fat mass; Gastric bypass; Lean body mass; Muscle mass; Protein deficiency; Sleeve gastrectomy.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / metabolism
  • Adult
  • Bariatric Surgery*
  • Biomarkers / urine
  • Body Composition
  • Body Mass Index
  • Body Weight
  • Dietary Proteins / administration & dosage*
  • Dietary Supplements*
  • Double-Blind Method
  • Energy Intake
  • Exercise
  • Female
  • Germany
  • Hand Strength
  • Humans
  • Male
  • Middle Aged
  • Obesity / surgery
  • Pilot Projects
  • Quality of Life
  • Treatment Outcome


  • Biomarkers
  • Dietary Proteins