The present invention is based on the discovery that mannoheptulose (mHep) reduces or inhibits the differentiation process of fat stem cells into adipocytes so as to decrease the body's fat storage capacity. Compositions comprising a mHep, process of making the compositions, and methods of using the compositions for treating or preventing overweight and obesity in a mammal, such as, for example, a growing pet (e.g., puppy, kitten), or a spayed/neutered pet, are encompassed by the present invention.