A Pilot 24-Week ‘Bulk and Cut’ Dietary Protocol Combined with Resistance Training Is Feasible and Improves Body Composition and TNF-α Concentrations in Untrained Adult Males

Background/Objectives: This study piloted a 24-week bodybuilding program, combining resistance training (RT) with a dietary bulk and cut protocol, in middle-aged adult males. Methods: Eleven untrained males (34 ± 3.5 years) were introduced to a 24-week intervention combining RT with a dietary protocol consisting of 12-week cycles of caloric bulking (0-12 weeks) and cutting (12-24 weeks). Of the 11 participants, 7 males with obesity (BMI=35.04.6 kg/m2, body fat=365 %) completed the program, yielding a 64% retention rate. The compliance to training was at 96.7% and adherence to dietary cycles over 93%. To assess preliminary efficacy of the intervention, venous blood samples, and measurements of body composition (BodPod), muscle strength, and VO2max (cycle ergometer) were collected at baseline (week 0) and following the bulking (week 12) and cutting (week 24) cycles. Circulating lipids (triglycerides, total, low-density and high-density cholesterol), C-reactive protein (CRP), tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) were measured in serum. Results: The training led to significant increases in muscle strength, especially in the deadlift (+46%, p<0.001) and the squat (+65%, p<0.001). Improvements in body composition were characterized by an increase in fat-free mass, and a decrease in body fat percentage over the 24-week intervention (+3% and -6%, respectively, p<0.05). Lipids, CRP, IL-6, and IL-10 did not change significantly, but there was a notable reduction in TNF-α (time effect p=0.05, pη2=0.39), with 15% lower concentrations at week 24 compared to baseline, indicating reduced inflammation. Conclusions: Overall, the pilot intervention was feasible and led to improvements in body composition and lower resting TNF-α concentrations in a group of adult males with overweight and obesity.