Conditions: Obesity Overweight Metabolic Diseases
Keywords: fatty acid oxidation Proton magnetic resonance spectroscopy
Allocation: NON_RANDOMIZED | Intervention model: PARALLEL
Enrollment: 39
Healthy volunteers: no

Brief summary:
The purpose of this study is to better understand the different ways our bodies burn fat which may be important for obesity, diabetes, and cardiovascular disease.

Detailed description:
In this study the investigators will examine the hypothesis that overweight/obese individuals that are unable to meet target weight loss goals on a low calorie diet (LCD) are intrinsically less metabolically flexible than their weight-losing counterparts. The investigators expect that this 'inflexibility' will be characterized by impaired fat oxidation (as determined by indirect calorimetry) in response to caloric restriction. If this were the case, these subjects may represent a population of 'super-responders' likely to demonstrate a robust response to approaches to increase fat oxidation. The investigators will also measure lipid concentrations in skeletal muscle and liver by hydrogen 1 magnetic resonance (1H-MRS) to determine both the stability of these measurements as well as the magnitude of changes that can be seen during LCD.

Arms:
arm 1: After screening, overweight/obese subjects (BMI \>27 - ≤40.0) subjects will be started on a low calorie diet (approximately 900-1000 kcal/d) until a target weight loss is achieved. arm 2: After screening, overweight/obese (BMI \>27.0 - ≤40.0) subjects will be started on a low calorie diet (approximately 900-1000 kcal/d) until a target weight loss is achieved. Individuals not on track to achieve their target weight by four weeks will receive the drug Phentermine to promote weight loss. Then, following eight weeks LCD (or four weeks LCD + four weeks LCD+Phentermine), in the event that they did not achieve the target weight loss, subjects will be given the option to continue with the LCD + Phentermine for up to an additional 12 weeks, under a doctor's supervision.

Interventions: intervention 1: Low Calorie Diet (LCD) intervention 2: Phentermine
Intervention descriptions: intervention 1: A Diet History Questionnaire was completed and subjects had dietary counseling and were provided shakes. The low calorie diet began, to continued for a period of 8 weeks. intervention 2: Individuals not on track to achieve their target weight by four weeks received the drug Phentermine to promote weight loss. Then, following eight weeks LCD (or four weeks LCD + four weeks LCD+Phentermine), in the event that they did not achieve the target weight loss, subjects were given the option to continue with the LCD + Phentermine for up to an additional 12 weeks, under a doctor's supervision.

Protection Against Risk:

* Prior to administering any phentermine, a history and physical including EKG will be conducted (at the screening visit) and will be used to determine whether the participant is clear to receive the medication.
* Participants will see the study doctor or nurse practitioner at every study visit after the drug is initiated.

Protocol document: