Disclosed are betaine and a Lycium chinensis leaf extract and a mixture thereof which are preventive and therapeutic of obesity, and uses thereof. They are found to have prophylactic and therapeutic effects on obesity and obesity-induced metabolic syndrome as evaluated for reductive activity against weight, body fat, total cholesterol, triglyceride, and LDL in humans and in mice. Thus, they can be used as active ingredients in pharmaceutical or health functional food compositions for the prevention and treatment of obesity or obesity-induced metabolic syndrome.
