My understanding in basic terms is that Ketosis is when your body turns to your 'fat reserves' for the extra energy it needs to keep you functioning. If you deviate from the diet with a sudden high calorie intake (compared to the very low calorie diet) you're body will stop using the fat for energy and use the energy from the food you eat instead. You then need to get back into Ketosis and you will have to go through the feeling hungry stage again. If you get there and stay there it's all downhill from there. I didn't believe it but now I know it to be true.
Many famous diets known for rapid weight loss such as vlcd's and atkins etc work predominantly because they put your body into ketosis because there is no other sources of fat for your body to process for energy.
In much the same way as athletes drink glucose drinks as a high source of carbs/sugars for extra energy we need to do the opposite and let the body find it's own natural source of energy.
If you are really struggling to cope without any 'real' food at all then maybe sole source isn't for you but remember that this is the quickest way to lose the weight. I would ignore the blip. Stay strong and try again. After 3/4 days you literally won't feel hungry because the body switches to feeding itself.
Like me I'm guessing the real struggle is the mental fight to physicaly stop putting hand to mouth and eating something solid. It's a weird experience for all of us but if you take each day as it comes and find the power to go to bed at night without cheating you can worry about tomorrow, tomorrow.
I'm sitting here talking like a pro and I'm on day 9 so trust me when I say you will be an absolute convert if you can do a full week on sole source and you get on those scales and see the drop. I know because I did it yesterday and I dropped 12 pounds in a week. My girlfriend dropped a stone on SS as well and men are supposed to lose quicker than women! I have been sitting on my backside all week and she's been at work walking all over London.
This is what excites me. How many diets out there allow you to lose a stone in a week when you barely leave the sofa? Weight Watchers meals certainly aren't going to offer those kind of results even if you're doing weight watchers. It's about rapid weight loss and it's bloody hard but you know it's going to be well worth it in the end.
People here say nothing tastes as good as being slim feels. Now I haven't been slim since I was about 9 years old but if it feels anything like what it feels to be a scrawny little 9 year old running around with bags of energy then it's worth looking forward to cause boy was life good then!
I'm really proud that not even a single crumb of something other than my food packs has passed my lips this week. It's a milestone where I can already feel my stomach shrinking and my confidence to succeed rising.
Knuckle down, give it another go and trust me when you see that number on the scale drop rapidly it will have been worth the struggle. It's a tough week that will make the rest of your life easier.
Good luck. You CAN do it and you WILL truly feel fantastic in no time. Trust me!