How long is 3rd week of hcg diet plan??? Buy the Best HCG Drops and Injections online For Weight Loss › Forums › HCG drops Phase 3 › How long is 3rd week of hcg diet plan??? This topic contains 1 reply, has 2 voices, and was last updated by Alyssa Vicens 12 months ago. Viewing 2 posts - 1 through 2 (of 2 total) Author Posts October 10, 2017 at 5:55 am #15320 SamanthaParticipant How long is phase 3 i.e. the 3rd week of hcg diet plan? I thought it was four weeks but my doctor said it is for three weeks. Please clarify. Thanks… October 20, 2017 at 11:24 am #16712 Alyssa VicensParticipant The maintenance phase i.e. Phase 3 is always 3 week period after you complete your hcg drops or shots. Author Posts Viewing 2 posts - 1 through 2 (of 2 total) You must be logged in to reply to this topic.