To specify the role of excessive weight gain during pregnancy in the development of gestosis, a prospective cohort study was conducted in 115 pregnant women with normal pregravid weight at baseline, 24 of whom had clinical and laboratory symptoms of gestosis. The baseline body mass index (18.5-24.9 kg/m2), gravid weight gain, and fat percentage were determined by caliperometry. The findings suggested that in normal-weight women, excessive weight gain (more than 16.5 kg) during pregnancy was associated with the more frequent incidence of gestosis in 42.9% of the pregnant women (OR=3.4; 95% CI 1.6-6.4; p=0.001). Weight gains of more than 500 g weekly in the second trimester (ξ2 =18.32; р<0.05) and 400 g weekly in the third trimester (ξ2 =14.89; р<0.05) substantially increased the likelihood of the complication. A significant moderate correlation was found between the risk of gestosis and fat percentage in the women, which progressively increased throughout the pregnancy: r=0.33 (р=0.003) in the first trimester, r=0.44 (р=0.05) in the second trimester, r=0.43 (р=0.05) in the third one, and r=0.43 (р=0.007) by labor. Multivariate analysis excluding the impact of baseline BMI in the woman showed that, irrespective of her pregravid weight, the fat percentage had a direct positive relation to the risk of gestosis (p=0.004).