The relationship between serum trace metallic elements and overweight and obesity is unclear, and few studies have evaluated the relationship between serum trace metal elements and overweight and obesity. Nine serum trace metallic elements of Ca, Cu, Fe, Mg, Mn, Mo, Se, V and Zn were detected in people with obesity and normal adults. Then 1865 adults from 2011–2016 cycles of National Health and Nutrition Examination Survey was included for a large sample analysis. Serum Cu is highly expressed in the people with obesity. The third quartile (Q3) (OR: 1.898, 95% CI: 1.173–3.071, P = 0.012) and fourth quartile (Q4) (OR: 2.047, 95% CI: 1.201–3.489, P = 0.011) of Cu were related to an increased likelihood of people with overweight and obesity. Subgroup analysis showed that high levels of serum Cu (OR: 1.011, 95% CI: 1.004–1.018, P = 0.002) were found may be a risk factor for overweight and obesity in females and in the 20–39 years old (OR: 1.010, 95% CI: 1.002–1.019, P = 0.020). The RCS models detect non-linear relationships between serum trace metallic elements and overweight and obesity. The study provides insights into the relationship between trace metallic elements and overweight and obesity, providing an opportunity for further investigation in this area.