We investigated the effect of acupuncture therapy on obese women's body weight and peripheral blood levels of serum immunoglobulin G ( IgG ), immunoglobulin A ( IgA ), immunoglobulin M ( IgM ), and immunoglobulin E ( IgE ). Sixty-three healthy women were assigned into 3 groups: placebo electroacupuncture ( n = 13; mean age, 40.5 ± 4.2 years; body mass index [BMI], 33.5 ± 4.2), diet restriction ( n = 23; mean age, 42.9 ± 4.0 years; BMI, 34.6 ± 2.9), and electroacupuncture ( n = 24; mean age, 40.1 ± 5.9 years; BMI, 33.9 ± 2.7). Electroacupuncture was applied to the Hunger and Shen Men ear points and to the LI 4, LI 11, St 36, St 44, and Ren 6 body points for 30 min once daily for 20 days. A restricted diet of 1400 kilocalories was given to participants in all 3 groups for 20 days. Weight was lost significantly in subjects in the electroacupuncture group compared to those in the diet restriction and placebo electroacupuncture groups ( p < 0.000, Tukey test). Modulations in serum IgG ( p < 0.001) were apparent in women treated with electroacupuncture compared with women treated with placebo electroacupuncture and restricted diet only. No significant changes were seen in serum IgA , IgM , and IgE levels among the 3 groups. Our results suggest that electroacupuncture can be effectively used to treat obesity. We also observed a modulating effect of serum IgG , which is associated with weight loss, in patients in the electroacupuncture group.