Iris Shai
Ben Gurion University, Israel
Title: Dynamic of human adipose tissues and ectopic fat deposits induced by different lifestyle interventions: a long-term MRI randomized trial
Biography
Biography: Iris Shai
Abstract
BACKGROUND: It remains unclear whether specific lifestyle strategies can differentially mobilize fat depots/ectopic-fat-deposits.
METHODS: During an 18-month trial in an isolated workplace with monitored, provided lunch, we randomly assigned participants with abdominal obesity/dyslipidemia to iso-caloric low-fat(LF) or low-carbohydrate/Mediterranean(LC/MED) diets. After 6 months, we re-randomized half of each arm to moderately-intense physical-activity (PA+;80%-aerobic; free gym membership). We performed whole-body magnetic-resonance-imaging (3-Tesla-MRI) at 0,6,18 months
RESULTS: Of 278 randomized participants [age=48yr;88% men; body-mass-index=30.8kg/m2) 86.3% completed the trial. While the caloric deficit was similar, the LF group preferentially decreased saturated/unsaturated fats (p<0.001), and the LC/MED decreased carbohydrates (p<0.001) and trans-fat intake (p=0.029 vs. other diet). The PA+ group increased their MET/wk (p=0.009 vs. PA-). Fat depots/deposits were significantly reduced to different degrees [Hepatic:(-32%);deep-subcutaneous-adipose-tissue(SAT):(-29%);visceral-adipose-tissue(VAT):(-25%);superficial-SAT:(-19%) and intra-pericardial:(-14%(-25mL))], with lesser changes of renal:(-9%);intermuscular:(-2%) and pancreatic-fat:(-1%). Although weight loss was comparable, LC/MEDPA+ favorably reduced waist-circumference (p<0.05), and induced -14% further loss of intra-pericaridal;p=0.003, -4% VAT;p=0.037 and -1.9% pancreatic-fat;p=0.007, compared to LFPA- changes (reference-group; weight-loss-adjusted for all). LC/MED decreased hepatic fat beyond LF diet by -15%;p=0.044. Conversely, renal-sinus and femoral-intermuscular fat dynamics were similarly altered by lifestyle strategies. VAT and intrahepatic fat loss associated with an improved lipid profile, and deep-SAT loss with improved glycemic control.
CONCLUSIONS: Human depots/ectopic-fat-deposits are substantially variable in their capacity to respond to different long-term moderate weight-loss strategies. LC/MED diet, particularly with PA, can favorably enhance fat mobilization in several depots. These findings may suggest defined lifestyle protocols for targeting specific fat storage sites.