Effect of Distinct Lifestyle Interventions on Mobilization of Fat Storage Pools: CENTRAL Magnetic Resonance Imaging Randomized Controlled Trial.

BACKGROUND: We aimed to assess whether distinct lifestyle strategies can differentially affect specific body adipose depots. METHODS: We performed an 18-month randomized controlled trial among 278 sedentary adults with abdominal obesity (75%) or dyslipidemia in an isolated workplace with a monitored provided lunch. Participants were randomized to isocaloric low-fat or Mediterranean/low-carbohydrate (MED/LC) diet+28 g walnuts/day with/without added moderate physical activity (PA; 80% aerobic; supervised/free gym membership). Overall primary outcome was body fat redistribution, and the main specific end point was visceral adipose tissue (VAT). We further followed the dynamics of different fat depots (deep and superficial subcutaneous, liver, pericardial, muscle, pancreas, and renal sinus) by magnetic resonance imaging. RESULTS: Of 278 participants (age, 48 years, 89% men, body mass index, 30.8 kg/m2), 86% completed the trial with good adherence. The low-fat group preferentially decreased reported fat intake (-21.0% versus -11.5% for the MED/LC; P<0.001), and the MED/LC group decreased reported carbohydrates intake (-39.5% versus -21.3% for the low-fat group; P<0.001). The PA+ groups significantly increased the metabolic equivalents per week versus the PA- groups (19.0 versus 2.1; P=0.009). Whereas final moderate weight loss was indifferent, exercise attenuated the waist circumference rebound with the greatest effect in the MED/LCPA+ group (P<0.05). VAT (-22%), intrahepatic (-29%), and intrapericardial (-11%) fats declines were higher than pancreatic and femur intermuscular fats (1% to 2%) loss. Independent of weight loss, PA+ with either diet had a significantly greater effect on decreasing VAT (mean of difference, -6.67cm2; 95% confidence interval, -14.8 to -0.45) compared with PA-. The MED/LC diet was superior to the low-fat diet in decreasing intrahepatic, intrapericardial, and pancreatic fats (P<0.05 for all). In contrast, renal sinus and femoral intermuscular fats were not differentially altered by lifestyle interventions but by weight loss per se. In multivariate models further adjusted for weight loss, losing VAT or intrahepatic fat was independently associated with improved lipid profile, losing deep subcutaneous adipose tissue with improved insulin sensitivity, and losing superficial subcutaneous adipose tissue remained neutral except for an association with decreased leptin. CONCLUSIONS: Moderate weight loss alone inadequately reflects the significant lifestyle effects on atherogenic and diabetogenic fat depots. The MED/LC diet mobilizes specific ectopic fat depots, and exercise has an independent contribution to VAT loss. Fat depots exhibit diverse responsiveness and are differentially related to cardiometabolic markers. Distinct lifestyle protocols may uniquely induce fat mobilization from specific anatomic sites. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01530724.

Dynamics of intrapericardial and extrapericardial fat tissues during long-term, dietary-induced, moderate weight loss.

Background: In view of evidence linking pericardial fat accumulation with increased cardiovascular disease risk, strategies to reduce its burden are needed. Data comparing the effects of specific long-term dietary interventions on pericardial fat tissue mobilization are sparse.Objective: We sought to evaluate intrapericardial-fat (IPF) and extrapericardial-fat (EPF) changes during weight-loss interventions by different dietary regimens.Design: During 18 mo of a randomized controlled trial, we compared a Mediterranean/low-carbohydrate (MED/LC) diet plus 28 g walnuts/d with a calorically equal low-fat (LF) diet among randomly assigned participants with moderate abdominal obesity. We performed whole-body MRI and volumetrically quantified IPF and EPF among 80 participants to follow the 18-mo changes.Results: The participants [mean age: 48.6 y; mean body mass index (BMI; in kg/m2); 31.7; 90% men] had baseline IPF and EPF (mean ± SD) volumes of 172.4 ± 53.3 mL and 194.9 ± 71.5 mL, respectively. The 18-mo moderate weight loss of 3.7 kg was similar in both groups, but the reduction in waist circumference was higher in the MED/LC group (-6.9 ± 6.6 cm) than in the LF diet group (-2.3 ± 6.5 cm; P = 0.01). After 18 mo, the IPF volume had reduced twice as much in the MED/LC group compared with the LF group [-37 ± 26.2 mL (-22% ± 15%) compared with -15.5 ± 26.2 mL (-8% ± 15%), respectively; P < 0.05, after adjustment for changes in weight or visceral adipose tissue]. The EPF volume had reduced similarly in both groups [-41.6 ± 30.2 mL (-23% ± 16%) in the MED/LC group compared with -37.9 ± 28.3 mL (-19% ± 14%) in the LF group; P > 0.1]. After controlling for weight loss, IPF and EPF volume reduction paralleled changes in lipid profile but not with improved glycemic profile variables: the IPF relative reduction was associated with a decrease in triglycerides (TGs) (ß = 0.090; 95% CI: 0.026, 0.154; P = 0.007) and the ratio of TGs to high-density lipoprotein (HDL) cholesterol (ß = 2.689; 95% CI: 0.373, 5.003; P = 0.024), and the EPF relative reduction was associated with an increase in HDL cholesterol (ß = -0.452; 95% CI: -0.880, -0.023; P = 0.039) and a decrease in total cholesterol and HDL cholesterol (ß = 3.766; 95% CI: 1.092, 6.440; P = 0.007).Conclusions: Moderate but persistent dietary-induced weight loss substantially decreased both IPF and EPF volumes. Reduction of pericardial adipose tissues is independently associated with an improved lipid profile. The Mediterranean diet, rich in unsaturated fats and restricted carbohydrates, is superior to an LF diet in terms of the IPF burden reduction. This trial was registered at clinicaltrials.gov as NCT01530724.