Hello Marymoo,
Yes, as sunshine-girl suggests, it would be good to see a food diary from the last couple of days. It may be that you are not eating enough! Or that you could make some useful food swaps within your carb and calorie allowance. The advice about eating full fat is spot on. You needn’t worry too much about that as you’ll find that you can eat less of whatever it is compared to the low fat/low sugar version as it will fill you up more quickly and stave off the hunger pangs for longer. I am definitely a Fage/Total full fat yoghurt fan! Generally tend to have that every morning with either a few strawberries or blueberries and often with a sprinkle of cinnamon. Eggs are definitely your friend on the BSD too. Small amounts of cheese and nuts are good. Olive oil and avocados should feature (if you like them!). And yes, fizzy water is another good tip and has often been my lifesaver!