Carnitine and Liver Mitochondria Fatty Acid Processing

Inclusion Criteria: * Age 20-40 years * BMI of 24.5-35.5 kg/m2 * Willingness to eat a prescribed diet of standard meals for a total of six days * Willingness to undergo carnitine or placebo supplementation for two weeks * Willingness to undergo study procedures including blood draws, MRS, C13 acetate infusion, DXA, muscle biopsy, and consumption of a sugary drink over the course of 6 hours Exclusion Criteria: * Unstable weight in the last 3 months (gain or loss \>7 lb (3.2 kg) * Significant changes in the diet or level of physical activity within the past month * Clinical history of diabetes or cancer * Clinically diagnosed heart, kidney, lung, thyroid, liver disease or abnormal liver enzymes that are, in the opinion of the investigator, clinically significant and represent a problem for study inclusion * Screening fasting glucose \> 125 mg/dL * Screening blood pressure \>140 systolic or \>90 diastolic * Use of certain prescribed medications at the discretion of the MI * Smoking or use of tobacco products in the last 6 months * Pregnancy or breastfeeding * Clinically diagnosed neuropsychiatric conditions * Diets that deviate extremely from the typical western diet in terms of increased meat intake are excluded, at the discretion of the MI. * Known aversion to or refusal to drink sugary beverages * Taking any over the counter drugs that alter the intestinal tract, at the discretion of the MI (for example, anti-cholinergic drugs and erythromycin) * Have taken carnitine supplements regularly in the past 3 months * Unwilling to discontinue use of dietary supplements containing significant amounts of carnitine or abstain from use one week prior to trial, at the discretion of the MI * Women who have undergone partial hysterectomy with intact ovarian function * Standard contra-indications to MRS, including non-removable metallic or electronic implants, claustrophobia or other fear of confinement, or inability to tolerate loud scanner noise * Calf does not fit into the MRI coil, at the discretion of the PI * Refusal to allow use of anonymized versions of collected data for research after this study is over