To investigate the regulatory effects of dietary fiber structure (β-glucan-to-arabinoxylan ratio, β/AX) and apparent viscosity (AV) on production performance in pigs, this study used a 2 × 3 factorial design, randomly assigning 36 growing pigs (47.2 ± 1.5 kg) to six dietary treatments (two AV levels and three β/AX ratios), and observed the growth performance, carcass traits, meat quality, intestinal microbiota, and liver lipid metabolism. The results showed that increased dietary β/AX and AV reduced subcutaneous fat deposition, improved meat tenderness and the nutrient content of meat, but decreased pig weight gain and dressing percentage. Increased dietary β/AX and AV selectively promoted the relative abundance of butyrate-producing bacteria and the concentration of butyrate in the middle colon, thereby regulating the expression of genes related to hepatic de novo lipid synthesis and oxidation, reducing serum glucose and total cholesterol levels, and increasing plasma glucagon-like peptide-1. These findings reveal the potential mechanism by which the physicochemical properties of dietary fiber mediate lipid metabolism to reduce weight gain and provide new insights for regulating fat deposition in pigs by controlling the structural and physical properties of dietary fiber.