Summary: This systematic review collates studies of dietary or bariatric surgery interventions for obesity using positron emission tomography and single‐photon emission computed tomography. Of 604 publications identified, 22 met inclusion criteria. Twelve studies assessed bariatric surgery (seven gastric bypass, five gastric bypass/sleeve gastrectomy), and ten dietary interventions (six low‐calorie diet, three very low‐calorie diet, one prolonged fasting). Thirteen studies examined neurotransmitter systems (six used tracers for dopamine DRD2/3 receptors: two each for 11C‐raclopride, 18F‐fallypride, 123I‐IBZM; one for dopamine transporter, 123I‐FP‐CIT; one used tracer for serotonin 5‐HT2A receptor, 18F‐altanserin; two used tracers for serotonin transporter, 11C‐DASB or 123I‐FP‐CIT; two used tracer for μ‐opioid receptor, 11C‐carfentanil; one used tracer for noradrenaline transporter, 11C‐MRB); seven studies assessed glucose uptake using 18F‐fluorodeoxyglucose; four studies assessed regional cerebral blood flow using 15O‐H2O (one study also used arterial spin labeling); and two studies measured fatty acid uptake using 18F‐FTHA and one using 11C‐palmitate. The review summarizes findings and correlations with clinical outcomes, eating behavior, and mechanistic mediators. The small number of studies using each tracer and intervention, lack of dietary intervention control groups in any surgical studies, heterogeneity in time since intervention and degree of weight loss, and small sample sizes hindered the drawing of robust conclusions across studies.
Bibliographical noteFunding Information:
The PsychoNeuroEndocrinology Research Group, Division of Psychiatry, Department of Brain Sciences, and Department of Metabolism, Digestion and Reproduction, Imperial College London are, or have been, funded by grants from the UK Medical Research Council (MRC), BBSRC, National Institute for Health and Care Research (NIHR) and Wellcome Trust. Infrastructure support was provided by the NIHR Biomedical Research Centre and the NIHR Imperial Clinical Research Facility. A.S.A. was funded by the Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia. S.A. was funded by the Deanship of Scientific Research at Princess Nourah Bint Abdulrahman University, Saudi Arabia through the Fast‐Track Research Funding Program. A.D.M. has received research funding from the MRC, NIHR, Jon Moulton Charity Trust, Fractyl, and Novo Nordisk. A.P.G. has received research funding from the MRC and Wellcome Trust. The views expressed in this manuscript are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.
© 2023 The Authors. Obesity Reviews published by John Wiley & Sons Ltd on behalf of World Obesity Federation.
- gastric bypass
- sleeve gastrectomy