I never used to eat breakfast or lunch, but found that once I was working full time, with an 8am start, by 10am I started to feel very muddled and wobbly. This was long before being diagnosed with diabetes, once I began eating a high fibre cereal for breakfast I was able to function much better at work.
Also, not eating regular meals does make it harder to resist the temptation to graze on high carb or high sugar snacks. I have fallen off the healthy eating wagon big style, hence coming to look at this forum. That comes from other factors, but when I was first diagnosed about 3 years ago, I cut sugar out straight away, reduced the carbs and lost 2 stone without even trying. If the differents diets work for you fantastic, well done for having that self discipline, (I hope that doesn't sound patronising because I really mean it). But if you are like me and struggle to follow these different eating regimes, don't feel that you are somehow failing. You are not, you can still lose the weight and feel better by just following a sensible eating regime and being a little more active.