The aim of this paper is to systematically review the evidence to explore whether smartphone applications that use self-regulatory strategies are beneficial for weight loss in overweight and obese adults over the age of 18 years. Sixteen electronic databases were searched for articles published up to April 2015 including MEDLINE, OVID, Ingenta, PSYCARTICLES and PSYCINFO, CINAHL, Sportdiscus, Science Direct, Web of Knowledge, Cochrane Library, JSTOR, EBSCO, Proquest, Wiley and Google Scholar. Twenty nine eligible studies were retrieved of which six studies met the inclusion criteria. Studies that recruited participants under the age of 18 years, adults with a chronic condition or did not report weight loss outcomes were excluded. Study findings were combined using a narrative synthesis. Overall, evidence suggests that smartphone applications may be a useful tool for self-regulating diet for weight loss as participants in the smartphone application group in all studies lost at least some bodyweight. However, when compared to other self-monitoring methods, there was no significant difference in the amount of weight lost. Findings should be interpreted with caution based on the design of the studies and the comparator groups used. Future research needs to be more methodologically rigorous and incorporate measures of whether eating habits become healthier in addition to measuring weight and BMI.