The minimum amount of time one can be on the HCG diet is 26 days, plus maintenance. Those 26 days break down as follows: 2 days of fat loading, 21 days of VLCD, 3 days of transitional VLCD. The maintenance phase is 6 weeks long and is broken into two stages (M1 & M2), each lasting 21 days. You can stop anytime up to the maximum of 55 days on VLCD.