Background: Cryolipolysis—a popular noninvasive technique for body contouring—has fewer side effects compared with liposuction; however, its effectiveness in terms of reducing local adipose tissue is also lower. This study is, to the authors’ knowledge, the first prospective, controlled, investigator-blinded split-body trial to evaluate whether postcryolipolytic heating can increase the efficacy. Methods: Twenty-five subjects were treated with one session of cryolipolysis on the lower abdomen and a subsequent heating with a mud pack of a randomized side of the treated region (left or right). Epidemiologic, temperature, edema, erythema, hypesthesia, and pain level data were obtained. Photographs, fat layer thickness (on ultrasound, caliper, and abdominal girth), satisfaction, and side effects were documented over a follow-up period of 12 weeks. Results: The side effects—edema, erythema, and hypesthesia—faded almost completely with heating, whereas they remained on the nonheated site. However, the mean sonographic reduction of local adipose tissue after 12 weeks was significantly lower on the heated sites than on the control sites (9.6% versus 14.1%; P = 0.0003). The overall satisfaction was high (9.2 of 10 points), even though only 44% of participants had a subjective recognition of fat loss without difference between the sites. Conclusions: Active heating following cryolipolysis increases bodily well-being by reducing common side effects, but it reduces the effectiveness of cryolipolysis significantly and should therefore be avoided. Further improvements are necessary to enhance the efficacy of cryolipolysis. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, I.