The HCG diet involves consuming very low calorie meals of 500 calories or less per day while taking homeopathic HCG injections or drops to induce weight loss. Proponents claim the HCG hormone helps mobilize stored body fat for energy when in a calorie restricted state. However, most medical professionals are skeptical of the HCG diet and consider it an unsafe way to lose weight due to potential side effects and a lack of scientific evidence proving HCG facilitates weight loss.