People suddenly thin and weight loss, should do the following tests: 1, gastrointestinal examination, all kinds of gastrointestinal diseases caused by gastrointestinal malfunction, will affect the digestion, absorption, so that people lose weight, weight loss. 2, blood sugar, diabetes mellitus, a typical symptom is three more than one, and one of the one less refers to the loss of body weight. 3, the thyroid function five and thyroid ultrasound, mainly to exclude the hyperthyroidism, hyperthyroidism, the metabolism is faster, will appear weight loss, panic, sweat and other symptoms. 4, malignant tumor, tumor is a consuming disease, in the process of disease development, will make people lose weight, fatigue and other symptoms. When hyperthyroidism occurs, the metabolism of a person is relatively fast, and there will be symptoms such as weight loss, panic, sweating, etc. 4, malignant tumors, tumors belong to the consumptive diseases, and in the process of disease development, it will make a person appear symptoms such as thinness and fatigue.