Study on the Mechanism of Regulating Gut Microbiome in Obese People by Regulating Brain-gut Axis With Fast Diet

1. Normal diet：Starting from May 20, 2018, the subjects will eat a normal diet for 4 days, with no restriction on calories and food types. The subjects are required to record their daily diet and dietary intake of calories.
2. Fast diet of High control ：From May 24, 2018, the method of fast diet was adopted on alternate days. According to the dietary records of normal diet, the normal caloric intake of each subject was calculated. Fast diet was carried out according to 2/3, 1/2, 1/3 and 1/4 of the original normal caloric intake.Each caloric stage last for 4 days, and the total cycle of fast diet was 31 days.
3. Fast diet of Low control ：After the intervention of fast diet of high control, the subjects were allowed to continue the diet fast diet every other day. It was suggested that the daily caloric intake was 600kal/ day for males and 500kal/ day for females.

1. Normal diet: the course of treatment was 4 days. The subjects were asked to record the daily diet and dietary intake in the daily observation scale (Table 1).
2. High control diet intervention: the course of treatment was 31 days. According to the actual intake of calories, 2 / 3, 1 / 2, 1 / 3 and 1 / 4 of the actual intake of the subjects were calculated as the light fasting calories. The treatment course of each calorie stage was 4 days. The subjects recorded the daily diet and dietary intake, and the nutritionists calculated the daily calorie intake and dietary types of each subject according to the daily calorie intake of each subject's normal diet. During the period of high control diet intervention, the diet on the day of light fasting was provided by the research group. Besides the diet provided by the research group, other foods (except water without calories) were strictly prohibited on the day of light fasting.
3. Low control diet intervention: the course of treatment was 31 days. It is suggested that the calorie intake of men and women should be 600 kcal / day and 500 kcal / day on the day of light fasting. The diet type can refer to the recipe made by the nutritionist.

Eligibility Criteria:
Inclusion Criteria:

1. BMI greater than or equal to 28 kg/m2, waist circumference greater than or equal to 90cm for men and 85cm for women.
2. Aged between 18 and 60.
3. Patients may be accompanied by diseases such as abnormal blood pressure, abnormal blood lipid, abnormal uric acid, metabolic syndrome, respiratory sleep, constipation, etc., but they can only participate in these diseases if there is no obvious risk after clinical evaluation.
4. No serious heart, brain, liver and kidney dysfunction, uremia coma, ketoacidosis, hypoglycemia, anemia, malnutrition, hematopoietic system and body immune system diseases, infectious diseases, neurological diseases.

5, the body does not contain the implantation or other metal materials such as the implantable metal denture, cardiac pacemaker, artificial joint, insulin pump and so on, no claustrophobia, non-pregnancy, suitable for magnetic resonance examination to participate in.

Exclusion Criteria:

1. those who do not meet the above diagnostic criteria have poor compliance and have not signed a voluntary informed consent to participate in the experimental study.
2. patients with severe cardiac, cerebral, hepatic and renal dysfunction, uremia coma, ketoacidosis, hypoglycemia, anemia, malnutrition, hematopoietic system and physical immune system diseases, infectious diseases, neurological diseases, etc.
3. special groups such as female menstruation, minors, pregnant women, and the elderly over 60 years old.