Excess body weight has been causally linked to an increased risk of different cancer types, including gastric cancer but the mechanisms underlying this relationship are not well understood. Superoxide generation rate, activity of complex I in electron transport chain of mitochondria, activity of matrix metalloproteinase (MMP-2 and 9) of adipose tissues (AT) of patients with gastric cancer in AT located adjacent to tumor (ATAT) and at a distance of 3 cm (ATD) are measured to follow the connection of the redox state with some of the microenvironment indicators (HIF-1α, CD68, Plin5), body mass index (BMI) and cancer metastasis. Superoxide generation rate in ATAT positively correlates with BMI (r = 0.59, p 0.05) being 4 times higher than in control (p 0.05). MMP-2, 9 activities in ATAT positively correlate with BMI (r = 0.67, p 0.05) being 3.3-4.0 higher than in control (p 0.05). In ATD a statistically significant increase of MMP-2 activity is found. In ATAT for the group of patients with distant metastasis (M1) the superoxide generation rate, MMP-2, 9 activities are about 2 times higher (p 0.05) than in the subgroup without distant metastases (M0). M1 is also characterized by the increased values of HIF-1α+ (factor 1.25), CD68+ (factor 1.4) and Plin5+ (factor 2.1) compared to M0 category in tumor tissues (p 0.05). The results can be used for better understanding the mechanism(s) of symbiosis of tumor and adipose tissues as well as serve as a basis for new therapeutic approaches.