Metabolic syndrome is characterized by central obesity, insulin resistance, elevated blood pressure, and dyslipidemia. Metabolic syndrome is a significant risk factor for several common cancers (e.g., liver, colorectal, breast, pancreas). Pharmacologic treatments used for the components of the metabolic syndrome appear to be insufficient to control cancer development in subjects with metabolic syndrome. Murine models showed that cancer has the slowest progression when there is no food consumption during the daily activity phase. Intermittent fasting from dawn to sunset is a form of fasting practiced during human activity hours. To test the anticancer effect of intermittent fasting from dawn to sunset in metabolic syndrome, we conducted a pilot study in 14 subjects with metabolic syndrome who fasted (no eating or drinking) from dawn to sunset for more than 14 h daily for four consecutive weeks. We collected serum samples before 4-week intermittent fasting, at the end of 4th week during 4-week intermittent fasting and 1 week after 4-week intermittent fasting. We performed serum proteomic analysis using nano ultra-high performance liquid chromatography-tandem mass spectrometry. We found a significant fold increase in the levels of several tumor suppressor and DNA repair gene protein products (GP)s at the end of 4th week during 4-week intermittent fasting (CALU, INTS6, KIT, CROCC, PIGR), and 1 week after 4-week intermittent fasting (CALU, CALR, IGFBP4, SEMA4B) compared with the levels before 4-week intermittent fasting. We also found a significant reduction in the levels of tumor promoter GPs at the end of 4th week during 4-week intermittent fasting (POLK, CD109, CAMP, NIFK, SRGN), and 1 week after 4-week intermittent fasting (CAMP, PLAC1) compared with the levels before 4-week intermittent fasting. Fasting from dawn to sunset for four weeks also induced an anti-diabetes proteome response by upregulating the key regulatory proteins of insulin signaling at the end of 4th week during 4-week intermittent fasting (VPS8, POLRMT, IGFBP-5) and 1 week after 4-week intermittent fasting (PRKCSH), and an anti-aging proteome response by upregulating H2B histone proteins 1 week after 4-week intermittent fasting. Subjects had a significant reduction in body mass index, waist circumference, and improvement in blood pressure that co-occurred with the anticancer, anti-diabetes, and anti-aging serum proteome response. These findings suggest that intermittent fasting from dawn to sunset actively modulates the respective genes and can be an adjunct treatment in metabolic syndrome. Further studies are needed to test the intermittent fasting from dawn to sunset in the prevention and treatment of metabolic syndrome-induced cancers.