Hi,
A few things can give you low losses.
Did you reduce your carbs and calories a week before starting sole source?
How many packs do you have a day?
Have you been 100% on your plan, nothing else passing your lips? (be truthful to yourself).
Have you been eating the cambridge spaghetti bolognaise or bars?
And lastly, have you been drinking more than 2.5lts of water?
xx