The present research protocol will analyze whether a short-term modification (one week) of dietary habits would have an impact on the postprandial metabolism of dietary fatty acids and on their uptake by non-adipose tissues, in healthy subjects.

Each subject will participate in two protocols randomly determined and separated by a period of one month: a 7-day isocaloric diet (Protocol A) and a 7-day carbohydrate-rich diet containing +50% of the subject's energy needs. (Protocol B).

At the end of each diet, the subject will go through a postprandial metabolic study of 8 hours where different parameters will be measured thanks to PET imaging and perfusions of stables isotopes.

Inclusion Criteria:

Healthy subjects: subjects with normal glucose tolerance determined according to an oral glucose tolerance test and with a BMI above 25 kg/m2 without first degree of familial history of type 2 diabetes (parents, siblings).

Exclusion Criteria:

• overt cardiovascular disease as assessed by medical history, physical exam, and abnormal ECG
• treatment with a fibrate, thiazolidinedione, beta-blocker or other drug known to affect lipid or carbohydrate metabolism (except statins, metformin, and other antihypertensive agents that can be safely interrupted)
• presence of liver or renal disease, uncontrolled thyroid disorder, previous pancreatitis, bleeding disorder, or other major illness
• smoking (>1 cigarette/day) and/or consumption of >2 alcoholic beverages per day
• prior history or current fasting plasma cholesterol level > 7 mmol/l or fasting TG > 5 mmol/l
• any other contraindication to temporarily interrupt current meds for lipids or hypertension
• being pregnant
• not be barren