Malignant tumor incidence showed an upgrade trend in recent years. Standard therapy for malignant tumor includes surgery followed by radiation and chemotherapy. Despite optimal treatment the prognosis remains poor. There is an urgent need for more effective therapies. The Warburg effect has been widely observed in human cancers. The main energy supply of tumor cells are aerobic glycolysis. Therefore, they are highly dependent on glucose metabolism. Recently, some scholars have suggested that 'Restricted calorie Ketogenic Diet (RKD)' might be able to inhibit glycolysis and thus anti-tumor by restricting carbohydrate intake. This will 'starve' cancer cells, which will lead to cell death. There are many animal and in vitro studies shown that RKD can reduce the tumor size and thus tumor cell growth of malignant tumors. However, a consistent positive result can not be found within a small sample of clinical trials. In this study, 40 patients with malignant tumors will be treated with or without RKD. The safety and efficacy of RKD and the patients' tolerance will be observed in order to understand whether this therapy can be a potential new treatment This clinical study is comparatively large internationally. It is the first domestically. This study is essential to extend the survival of patients with malignant tumors, and to study clinical nutrition support and its metabolic pathways for malignant tumors.

Inclusion Criteria:

1. 40 patients with diagnosed/recurrent malignant tumors
2. Ability and willingness to sign informed consent form.

Exclusion Criteria:

1. Anticoagulation treatment with coumadin≥ 1 mg/day for ≤ 7 days prior to screening (low-dose [≤ 1 mg/day] coumadin, heparin, and low-molecular-weight heparin are permitted)
2. Any systemic illness or unstable medical condition that might pose additional risk, including: cardiac, unstable metabolic or endocrine disturbances, renal or liver disease, past history of renal calculi, hyperuricemia, hypercalcemia, mitochondrial disease, known disorder of fatty acid metabolism, porphyria, carnitine deficiency and pancreatitis
3. History of malignant tumors other than malignant glioma, such as surgical resection of non-melanoma skin cancer or cervical carcinoma in situ.
4. History of uncontrollable hyperlipidemia.
5. Active drug or alcohol dependence or any other factors that, in the opinion of the site investigators, would interfere with adherence to study requirements
6. History of having human immunodeficiency virus, or hepatitis C
7. Failure to recover from \