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NCT Number: NCT07156552

Protein Supplementation and Resistance Training to Prevent Fat-Free Mass Loss Following Metabolic-Bariatric Surgery

The goal of this clinical trial is to investigate the effects of daily protein supplementation and participation in a weekly supervised resistance training program on the prevention of excessive muscle mass loss following bariatric surgery. Patients treated at one of the participating centers will be invited to participate and will be randomly assigned to one of two groups.

Participants in group 1 will receive standard postoperative care as currently provided. Participants in group 2 will also receive standard care, but in addition, they will be asked to consume extra protein daily and take part in a supervised resistance training session once a week.

Previous research has shown that approximately one in five patients undergoing bariatric surgery experiences excessive muscle loss after the surgery. It is known that resistance training and protein intake can help maintain and even improve muscle mass. However, limited research has been conducted on the combined effects of protein supplementation and resistance training in patients after bariatric surgery. Therefore, the aim of this trial is to determine whether participants receiving the additional intervention experience less muscle mass loss compared to those receiving standard care alone.

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Key information

Conditions

Bariatric Surgery Fat Free Mass

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Nederlandse Obesitas Kliniek, Amsterdam, Netherlands

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • A scheduled metabolic-bariatric surgery (i.e. RYGB or Sleeve Gastrectomy)
  • Participation in the NOK care program
  • Able to understand and perform the study procedures

Exclusion criteria

  • Allergic or sensitive for milk proteins, or lactose intolerant
  • Diagnosed renal insufficiency
  • Diagnosed intestinal diseases influencing the uptake of protein (i.e. active inflammatory bowel disease

Treatment and study plan

Resistance exercise training and protein supplementation

Behavioral

The intervention consists of two components:

  • Resistance Exercise Training Participants will engage in a 24-week resistance training program. This program includes one supervised session per week supervised by a qualified kinesiologist, complemented by two to three additional unsupervised sessions per week performed at home.
  • Protein Supplementation

Participants will receive daily protein supplements for a total duration of 12 weeks. The dosage will be progressively increased:

  • 20 grams per day during weeks 1-4
  • 40 grams per day during weeks 5-8
  • 60 grams per day during weeks 9-12 After the 12-week supplementation period, participants will receive additional dietary counseling sessions with a dietitian. These sessions aim to support the maintenance of adequate protein intake through dietary intake.

Primary outcomes

  1. Prevalence of Fat-free mass loss/Total weight loss >30%

    Time frame: From enrollment to 3 months post-surgery

Secondary outcomes

  1. Weight (kg)

    Time frame: From enrollment to 12 months post-surgery

  2. Body Mass Index (kg/m2)

    Time frame: From enrollment to 12 months post-surgery

  3. Body composition (fat-mass/fat-free mass) (kg)

    Time frame: From enrollment to 12 months post-surgery

  4. Waist circumference (cm)

    Time frame: From enrollment to 12 months post-surgery

  5. Blood pressure (mmHg)

    Time frame: From enrollment to 12 months post-surgery

  6. Quadriceps isometric strength (kg)

    Time frame: From enrollment to 12 months post-surgery

  7. Quadriceps isometric power (Watt)

    Time frame: From enrollment to 12 months post-surgery

  8. Handgrip strength (kg)

    Time frame: From enrollment to 12 months post-surgery

  9. Short Physical Performance Battery (SPPB) score (scale 1-12 points)

    Time frame: From enrollment to 12 months post-surgery

    Based on a balance test (0-4 points), a gait speed test (0-4 points), and a repeated chair stand (0-4 points)

  10. VO2max (L/min)

    Time frame: From enrollment to 12 months post-surgery

    Assessment using the Astrand-Rhyming six minute cycle ergometer test

  11. Incidence of gastrointestinal symptoms

    Time frame: From enrollment to 12 months post-surgery

    Assessment using the Gastrointestinal Symptom Rating Scale (GSRS) questionnaire

  12. Difference in Health-Related Quality of Life (HRQoL)

    Time frame: From enrollment to 12 months post-surgery

    Assessment using the BODY-Q questionnaire

  13. Healthcare consumption (costs)

    Time frame: From enrollment to 12 months post-surgery

  14. Blood marker HOMA-IR

    Time frame: From enrollment to 12 months post-surgery

    Based on fasted insulin (microU/mL) and glucose (mmol/L) levels

  15. Blood marker high-sensitivity C-Reactive Protein (hs-CRP) (mg/L)

    Time frame: From enrollment to 12 months post-surgery

  16. Blood marker lipid profile

    Time frame: From enrollment to 12 months post-surgery

    Based on HDL-cholesterol (mg/dL), LDL-cholesterol (mg/dL), and triglycerides (mg/dL)

Study contacts

Contact information is provided by the study sponsor or research team.

B. M. de Roos, Drs.

CONTACT

[email protected]

+31681363125

J. H.M. Karregat, Dr.

CONTACT

[email protected]

+31653461919

Sponsors and collaborators

Lead sponsor

Radboud University Medical Center

Other

Collaborators

  • Amsterdam University Medical Centers (UMC), Location Academic Medical Center (AMC)
  • Nederlandse Obesitas Kliniek
  • ZonMw: The Netherlands Organisation for Health Research and Development

Registry information

Official study title

Effectiveness of Protein SupplementatIon Combined With Resistance Exercise Training to Counteract Disproportional Fat-Free Mass Loss Following Metabolic-Bariatric Surgery: The ENRICHED Study

Acronym: ENRICHED

Important dates

Study start
2025
Primary completion
2026
Study completion
2027
First posted
Sep 5, 2025
Registry last updated
Sep 5, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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