I only lost 4lbs in week one, despite being 100% and drinking tons of water. A bit disappointed but not discouraged. First day of week two done. BRING. IT. ON.
Don't worry, I just had my first weekly weigh-in and only lost 2.5 lbs. It may be that you didn't have a lot of water weight so most of what you lost was actual fat, or some people's bodies may be more reluctant to adjust.. Besides 4lbs is still a massive loss in a week, don't get disheartened by some of the huge first week losses on here as noone maintains that sort of loss