Preparation and methods of treating and preventing visceral adiposity and cancer are provided involving the administration of stearate to a subject. It has been unexpectedly discovered that the fatty acid stearate, when introduced in the diet, reduces the amount of visceral fat in the body without decreasing overall body weight or causing measurable negative side effects. It has also been unexpectedly discovered that dietary stearate prevents cancer in healthy subjects and reduces both tumor size and metastasis in subjects already afflicted with cancer.