This study in which individuals overate for 8 weeks showed dramatic worsening of the risk of cardiovascular disease, with increases in weight (7kg!), body fat, visceral fat, inflammation, fasting blood glucose, insulin resistance and cardiovascular risk.
http://www.ncbi.nlm.nih.gov/pubmed/23347533
The subjects ate 1.4 times their daily energy requirements (with a diet composed of 41% carbohydrate, 44% fat, and 15% protein). So, for example, if your daily energy requirement is 2000 kcals, eating 2800 for 8 weeks is enough to cause significant damage to your body.
http://www.ncbi.nlm.nih.gov/pubmed/23347533
The subjects ate 1.4 times their daily energy requirements (with a diet composed of 41% carbohydrate, 44% fat, and 15% protein). So, for example, if your daily energy requirement is 2000 kcals, eating 2800 for 8 weeks is enough to cause significant damage to your body.