This study evaluated the impact of eating fast food (2 meals/day) with the adoption of a sedentary lifestyle for 4 weeks on components of the metabolic syndrome in healthy nonobese men (n=12) and women (n=6). Body weight increased from 67.6 kg to 74.0 kg (p<0.001) with no sex difference. The increase in waist circumference and the absolute increase in abdominal fat volumes [subcutaneous, intra-abdominal (visceral) and retroperitoneal] were similar in both men and women. However, the increase in the proportion of the volume of fat accumulated in the intra-abdominal region (percentage of the total increase in abdominal fat volume) was different between men and women. For instance, 41.4 ± 9.2% of the increase of fat volume in the abdominal region was accumulated in the intra-abdominal depot in men compared to 22.7 ± 6.5% in women (p<0.0001). Fasting insulin levels, systolic blood pressure, LDL cholesterol and apolipoprotein B concentrations increased only in men. Thus, under similar unhealthy habits, men develop a more deteriorated cardiovascular risk profile than women which could be explained by a greater accumulation of intra-abdominal fat in men than in women.