In Group A the expected changes in cholesterol values, regarding baseline, can be observed 3 months after TDF/FTC addition. After this, a period of 3 months with placebo will act as a washout period, allowing establishing comparisons intra-patient. Finally, another period of 3 months with placebo will permit to establish comparisons with the first 3-month TDF/FTC intervention. In Group B, subjects will follow a 3-month placebo period, later a 3-month TDF/FTC intervention and finally a placebo period that will act as a wash-out.