Exercise Training at Maximal Fat Oxidation Intensity for Body Composition and Cardiometabolic Health in People With Overweight and Obesity: A Systematic Review With Meta‐Analysis Focusing on Prescription Dosage and Potential Moderators

While exercise training at maximal fat oxidation intensity (FAT_max) is recognized as an effective strategy for improving body composition in people with overweight or obesity, its efficacy regarding cardiometabolic health and optimal prescription warrants systematic evaluation. We conducted a PRISMA-conform systematic review and meta-analysis (PROSPERO: CRD420251036468), reviewing literature from PubMed, Cochrane Library, Embase, SPORTDiscus, and Web of Science through December 6, 2025. A three-level random-effects model with restricted maximum likelihood (REML) was applied. Study quality was assessed with the TESTEX scale and Cochrane RoB 2.0, and certainty with GRADE. Nineteen randomized trials (N = 644; overweight/obesity) were included, with overall moderate methodological quality. Compared with controls, exercise training at FAT_max reduced body weight (-3.66 kg, p < 0.01), BMI (-1.66 kg/m², p < 0.01), body fat percentage (-2.32%, p < 0.01), fat mass (-2.86 kg, p < 0.01), and waist circumference (-4.21 cm, p < 0.01), and improved <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:msub><mml:mi>O</mml:mi> <mml:mrow><mml:mn>2</mml:mn> <mml:mi>max</mml:mi></mml:mrow> </mml:msub> </mml:mrow> <mml:annotation>$$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$</mml:annotation></mml:semantics> </mml:math> (SMD = 1.45, p < 0.01) while reducing fasting circulating glucose (SMD = -1.28, p < 0.01), insulin (SMD = -0.53, p < 0.01), and HOMA-IR (SMD = -0.57, p < 0.01). Moderator analyzes indicated significant influences of age, BMI, ethnicity, and methodological design on selected outcomes. Nonlinear dose-response modeling identified an optimal total exercise volume of ~2446 min for maximal body composition benefit. Overall GRADE ratings were predominantly very low to moderate. In conclusion, exercise training at FAT_max can effectively improve body composition and cardiometabolic health, but standardized assessment protocols are needed to mitigate methodological heterogeneity and refine tailored FITT-VP exercise prescriptions.