Clinical Application of Periodized Resistance Training during a 12-Week Hypocaloric Treatment for Obesity

Introduction. Medically prescribed very-low calorie diet (VLCD) systems have shown efficacy in producing clinically significant weight-loss in obese patients. This loss in bodyweight (BW), however, cannot be solely accounted for by reduced adiposity, but also significant deficits in lean tissue. With respect to these frequently reported weight-loss patterns for lean body mass (LBM), the potential for optimum weight-loss as well as sustainable weight-maintenance is adversely affected on a number of levels. Lowered resting metabolic rate (RMR), neuromuscular impediments, and poor physical function have been reported to occur as a result of reduced LBM. Any of these factors taken together with a dramatic loss of lean tissue would be a condition that is conducive to impeded fat reduction, weight-regain, and relapses of prior health complications. Therefore, the main objective of this single-center clinical study was to evaluate the efficacy by which periodized resistance training enhances morphometric, metabolic, and functional outcomes for obese patients undergoing a 12-week medically supervised hypocaloric treatment. Methods. The target population was obese patients of the Tallahassee Memorial Healthcare (TMH) Bariatric Center prescribed to undergo a 12-week proprietary VLCD treatment (Optifast®). A two-pronged experimental approach was applied through the following specific aims: 1) to determine the longitudinal responses for various clinical and weight-loss parameters in patients who have fully completed the 12-week VLCD program at the TMH Bariatric Center; and 2) to determine the effects of periodized resistance training on body composition, RMR, neuromuscular function, and biochemical responses in obese participants undergoing 12 weeks of a protein-supplemented Optifast® treatment. For Specific Aim 1, data for anthropometric measures, body composition (via BIA), and lipid/ metabolic profiles were acquired before and after the 12-week VLCD treatment in male (n=16) and female (n=16) patients. Gender- and age-dependent responses were examined for each variable over time. For Specific Aim 2, male and female participants were placed in one of two groups for 12 weeks: 1) Standard Treatment Control (CON) (n=4) or 2) Periodized Resistance Training (RT) (n=4). All participants consumed 1120 kcals/day by way of Optifast® products and whey protein supplementation. Both groups underwent a pedometer-based walking program; however only RT performed periodized resistance training 3 days/week for 12 weeks. Body composition (via DXA), RMR (via indirect calorimetry) and neuromuscular function (via isokinetic and isotonic tests) were measured at pre-, mid-, and post-intervention. Serum free fatty acid (FFA), free glycerol, beta-hydroxybutyrate (β-HB), insulin-like growth factor 1 (IGF-1), IGF-1 binding protein 3 (IGFBP-3), and cortisol were analyzed (via ELISA) were analyzed for samples obtained at pre, mid, and post. Results. Specific Aim 1: Patients lost 22.5 kg of BW, 16.6 kg of fat mass (FMBIA), and 5.6 kg of fat free mass (FFM= BW-FMBIA) (p<0.05). The decline in FM and FFM composed 73% and 27%, respectively, of the total weight-loss. Males lost more BW than females solely due to a larger reduction in FM (p<0.05). No gender-differences were found for relative weight-loss composition. BW-loss was similar between age-groups; however the younger patients (<57yrs) lost more FM and less FFM than the older age-cohort (≥57yrs) (p<0.05). Relative weight-loss composition was significantly different between age-groups (Young: 81% FM and 19% FFM vs. Old: 65% FM and 35% FFM). Specific Aim 2: Total body mass (TBM) and FM decreased (p<0.05) pre to post in CON (-20.4 kg BW; -15.3 kg FM) and RT (-14.6 kg BW; -13.4 kg FM) with no group differences. There was a group by time interaction for LBM (LBM=TBM-FM-bone mineral content) as CON lost 5.0 kg from pre to post (p<0.05) while RT showed no significant changes. Relative weight-loss composition differed between groups (CON: 75% FM and 25% FFM vs. RT: 90% FM and 10% LBM) (p<0.05). There was a group by time interaction for RMR as CON experienced a 350.7 kcal/day decrease from pre to post (p<0.05) while RT exhibited no changes. RT demonstrated greater improvements in all measures of contractile kinetics and isotonic strength when compared to CON (p<0.05). At post-treatment, there was a significant group difference for overall change in serum FFA (CON: -40.3% vs. RT: +41.5%), glycerol (CON: -30.9% vs. RT: +30.8%) and β-HB (CON: -31.2% vs. RT: +36.6%). IGF-1 decreased (p<0.05) from pre to post for CON (-45.2%) and RT (-33.7 %), with no group differences. IGFBP-3 increased significantly from pre to post in RT (+18.9%) but not in CON. IGF-1 to IGFBP-3 ratio decreased (p<0.05) from pre to post with no group differences. Cortisol levels remained unchanged for both groups. Conclusion. Specific Aim 1 confirms the need to restructure current VLCD-based programs towards outcomes more conducive for long-term weight- and health-management. This led to Specific Aim 2 in which the outcomes showed resistance training to be advantageous for weight-loss composition through preserving LBM without compromising overall weight- or fat-loss. These changes corresponded to positive adaptations for energy metabolism and muscular function. Our findings offer compelling support for the clinical integration of periodized resistance training in obesity therapeutics utilizing VLCDs with promising implications for chronic weight-management.