Positive Effects of Aerobic-Resistance Exercise and an Ad Libitum High-Protein, Low-Glycemic Index Diet on Irisin, Omentin, and Dyslipidemia in Men with Abdominal Obesity: A Randomized Controlled Trial

Abstract

Objectives: The aim of this research was to evaluate changes in body composition, adipokine levels, and dyslipidemia parameters in males with abdominal obesity following two distinct interventions: exercise alone and exercise combined with an ad libitum diet.

Methods: This study included 44 males with abdominal obesity (mean age 34.7 ± 5.5 years, waist circumference [WC] 110.3 ± 8.5, BMI 32.0 ± 3.9), who were randomly assigned to three groups: an experimental group engaging in aerobic-resistance exercise (II, n = 16), an experimental group engaging in aerobic-resistance exercise combined with an ad libitum high-protein, low-glycemic index carbohydrate diet (III, n = 16), both interventions lasting 6 weeks, and a control group without interventions (I, n = 12). Body composition metrics (body mass index [BMI], waist circumference [WC], body fat [BF], abdominal fat [ABD]) and fat-free mass [FFM], along with biochemical blood analyses (irisin [IR], omentin [OMEN], glucose [GLU], insulin [INS], LDL- and HDL-cholesterol), were measured at baseline and after the 6-week intervention. The effects of the interventions on the analyzed variables across groups were assessed using mixed ANOVA tests with post-hoc comparisons. Effect size (ES) was also calculated using partial eta squared (ηp²).

Results: The intervention in group III resulted in a significant decrease in IR (p < 0.01, ηp² = 0.03) by 41% and LDL-C (p < 0.01, ηp² = 0.02) by 14%. These effects were associated with a reduction in BF (p < 0.01, ηp² = 0.02) by 14%, ABD (p < 0.01, ηp² = 0.03) by 31%, and WC (p < 0.01, ηp² = 0.01) by 3%. In group II, decreases after 6 weeks of intervention were noted only in WC (p = 0.02, ηp² = 0.01) by 1% and in INS (p < 0.01, ηp² = 0.04) by 47%. No differences were found between groups. The use of low-glycemic index carbohydrates (p < 0.01, ηp² = 0.06) and increased protein intake (p < 0.01, ηp² = 0.30) led to changes in the fiber-to-energy value of the diet ratio (p < 0.01, ηp² = 0.18) and a reduction in dietary energy value (p < 0.01, ηp² = 0.13) by 23%, resulting in a greater energy deficit than in the II group.

Conclusions: These findings highlight the effect of combining dietary and exercise interventions to achieve significant changes in body composition and metabolic parameters, even over a short period of intervention.

Keywords: abdominal obesity; aerobic-resistance exercise; body mass index; carbohydrates; fiber; irisin; low-glycemic index; omentin; protein intake.

Figure 1

Study flowchart.

Figure 2

Variation in irisin (IR) [ng/mL] concentration in the control (CG I), exercise (EG II), and exercise–diet (EGD III) groups at baseline and after six weeks.