No trained/ qualified staff available to perform study.

To study the effects of transcranial direct current stimulation (tDCS) on weight and appetite.

1. To compare weight loss over one month in active tDCS group with sham tDCS group. The investigator will measure weight of every participants at the beginning of the study and one month after the last session of tDCS
2. To compare change in insulin sensitivity over one month in active tDCS group with sham tDCS group. The investigator will measure fasting insulin and glucose level, and calculate homeostatic model assessment-insulin resistance (HOMA-IR)
3. To compare change in cognitive performance as a response to food over one month in active tDCS group with sham tDCS group. The investigator will evaluate performance in a computerized task that measures executive functions under the presence of food (working memory, inhibitory control and a combination of both). The investigator will assess changes in accuracy and speed in the task under active tDCS versus sham tDCS.
4. To compare change in post-prandial glucose excursion and average meal counts per day. The investigator will use continuous glucose monitor to record the frequency and amplitude of glucose excursion.

Inclusion Criteria:

• Men and women 18 to 80 years of age
• Body mass index > 30 kg/m2

Exclusion Criteria:

• Current participation in any other concurrent clinical trials or previous participation within 30 days before the screening visit

• Pregnancy or premenopausal women who are trying to be pregnant

• Patients who are incompetent to give consent

• Obesity due to a known secondary cause (Cushing's syndrome, hypothyroidism, etc) or a history of weight loss surgery

• Have taken any of the following medications within the past 3 months:

  • phentermine, naltrexone, bupropion, topiratmate, lorcaserin, phendimetrazine, methamphetamine, benzphetamine, diethylpropion

• Any contraindication to receive transcranial direct current stimulation (tDCS):

  • Personal or family history of seizures, epilepsy or other unexplained loss of consciousness.
  • Current or past history of skin disease or damaged skin on the scalp at the site of stimulation (i.e. eczema, skin with ingrown hairs, acne, razor nicks, wounds that have not healed, recent scar tissue, broken skin, etc.).
  • Prior neurosurgical procedure or radiation.
  • Known diagnosis of brain lesions, such as tumor, stroke or multiple sclerosis
  • Implanted pacemaker, medication pump, vagal stimulator, deep brain stimulator, Transcutaneous Electrical Nerve Stimulation unit, ventriculo-peritoneal shunt or any metallic implant on the head.

5 weeks