This is a randomized, controlled, double blind clinical trial. The purpose of this study is to investigate the weight loss efficacy of entacapone. In this study, participants are randomly divided into entacapone and placebo groups. The percentage change in body weight, the body mass index, waist circumstance, extent of fatty liver, quantity of visceral fat, serum insulin, serum triglyceride and the adverse effects are compared between the two groups.

All volunteers should clearly understand the objectives and the risks of the present study. Then, all volunteers should carefully read and sign the informed consent and receive a copy of the signed informed consent. If the volunteer agrees to participate to the present study and signs the informed consent, the volunteer is included. The included participants should be followed up and the case report form should be competed by appointed researchers.

Recruiting stage:

To check whether a volunteer are eligible to participate:

1. All volunteers are checked according to the inclusive and the exclusive criteria;
2. The clinical nutritionists provide diet and exercise regime to the volunteers.

Grouping stage:

A group of 12 Participants enter the study at a time,

1. To assess the performance of the volunteer complying the diet and exercise regime;
2. Volunteers who are able to comply the regime and sign the informed consent are included;
3. Every participate receives a random number which is packed in an opaque envelop;
4. Physical examination: blood pressure, heart rate, height, bodyweight, waist and hip circumference;
5. Laboratory examination: level of adiponectin, leptin, resistin, C-reactive protin, insulin, fasting blood glucose, haemoglobin A1c, tri glycerides, total cholesterol, LDL cholesterol, HDL cholesterol;
6. Extra blood sample(20ml) is collected to measure the level of adiponectin, resistin and leptin;
7. The opaque envelop contained the random number is opened by the CRA and the grouping is determined;
8. Participants take entacapone or placebo as the physicians and researchers have instructed and make a record in a standard form;
9. Participants carry out the diet and exercise regime, measure their bodyweight everyday and take a record.

Intervening stage:

1. Two weeks after the first intervention, monthly telephone interview start:

   1.1 Ask the participant the details of taking medicine, following the diet and exercise regime, the present body weight; 1.2 Ask the participant whether they have any discomfort and to decide whether medical interventions are needed.

2. Four weeks after the first intervention, monthly hospital interview start:

2.1 The day before the participants go to hospital for the second interview. 2.1.1 Any drink, food and strenuous activity should be avoided at least 8 hours before the second interview; 2.1.2 The standard form of daily activity should be brought. 2.2 During this interview: 2.2.1 Physical examination：blood pressure, heart rate, height, bodyweight, waist and hip circumference; 2.2.2 The details of participants taking medicine, following the diet and exercise regime should be asked; 2.2.3 Laboratory examination: level of adiponectin, leptin, resistin, C-reactive protin, insulin, fasting blood glucose, haemoglobin A1c, triglycerides, total cholesterol, LDL cholesterol, HDL cholesterol; 2.2.4 20ml blood sample is collected to measure the level of adiponectin, resistin, leptin and the expression of obese related genes; 2.2.5 Abdominal MRI should be made; 2.2.6 Any discomfort of the participants should be recorded and medical treatment should be provided when it is necessary; 2.2.7 The previous standard form of daily activity are hand over to the CRA and blank forms are provided; 2.2.8 The untaken drugs should be retrieved, packed and a record should be maed; 2.2.9 Drugs of the next month should be distributed and a relevant record should be made.

2.3 Participate go back home. 2.3.1 Participants continue to take entacapone or placebo as the physicians and researchers have instructed and make a record in a standard form; 2.3.2 Participants continue to carry out the diet and exercise regime, measure their bodyweight everyday and take a record.

All the data should be recorded in a standard case report form and the accuracy, completeness and timeliness be regularly checked by an appointed clinical research associate.

The sample size is calculated by the software PASS 11.0. The alternative hypothesis set as Mean 1\

Inclusion Criteria:

• 1) Obese which is defined as BMI ≥ 28kg/m2 ;
• 2) 18≤ age ≤60 years;
• 3) Permanent resident in Xi'an City, Shaanxi Province, China

Exclusion Criteria:

• 1) Unable to closely follow the diet and exercise regime;
• 2) Bodyweight changes beyond 4kg within 3 month before participating in this study;
• 3) Have a history of myocardial infarction or unstable angina within 6 month before participating in this study;
• 4) With endocrine, neurological, psychiatric or malignant diseases;
• 5) History of thyroid diseases;
• 6) Cardiac, hepatic and renal dysfunction;
• 7) Have a long history of using amcinonide;
• 8) With intestinal malabsorption;
• 9) With history of acute or chronic pancreatitis
• 10) With history of gastrointestinal surgery;
• 11) With history of bariatric surgery;
• 12) Using any other pharmacological drugs for weight loss;
• 13) Addicted to any drugs including alcohol;
• 14) Diabetes;