The constitution of traditional Chinese medicine was established in 1970s by Chinese scholars, in which the constitutions of Chinese people were classified into nine types for study. The phlegm-dampness constitution is one of the nine constitutions and is the most common type in constitution study. Genomics studies found four upregulated genes: COPS8, GNPDA1, CD52 and ARPC3; and six downregulated genes: GSPT2, CACNB2, FLJ20584, UXS1, IL21R and TNPO in the phlegm-dampness constitution. Gene functional analyses on genes affecting the differences between the phlegm-dampness constitution and the balanced constitution indicated that people with phlegm-dampness constitution were susceptible to hyperlipemia and diabetes. Results of epidemiological surveys also revealed that people with phlegm-dampness constitution have a much higher risk of obesity, metabolic syndrome, hypertension and diabetes than people with a balanced constitution. Therefore, differentiation of phlegm-dampness constitution could be performed in the normal population with the Constitution of Chinese Medicine Scale to estimate the risks of those diseases for prediction. For people with phlegm-dampness constitution, Chinese medicine could be used to reduce risk of related diseases. Constitution-based strategies in disease prevention and treatment are consistent with the current proposed 4P medical mode (personalized, predictive, preventive and participatory). With the rising burden of global disease and increasing medical expenditure, the objectives of medicine are transforming from treatment to prevention. Thus, studies on the phlegm-dampness constitution of traditional Chinese medicine are significantly important for the prediction and prevention of related diseases and maintenance of human health.