rebecca123 what type of plan are you following? it seems these guys are on a pretty specific plan as to the amounts of carbs they allow themselves a day. You have that you are low-carb, some consider under 50g per day low carb - so depending on your plan and what you are allowing your self and how your body feels should dictate how soon and how much. Listen to your body. write down what you eat and what you do at the gym or otherwise and how you are feeling the following day. Supplementing food for hunger after a good days work out is okay as long as you follow your particular plan. If you are low carb and still feel the need for energy try to add in some Fish Oil tablets a little at a time to increase the fat in your diet, keeping your carbs low. Just my 2 cents i hope that helps.
BTW
I do a full body circuit every Saturday I lift heavy and slow.
Then 30 minutes of cardio
then every day to every other day I make it a point to walk at least 30 minutes, jog if I want to, but as long as it's 30 minutes every other day.
You should never have an excuse to pig out, it takes time your body is going through a metabolic shift - it's like sending a text message....it might take some time for the body to receive the message.