OK so I started reading and it might be useful to Elapid:
The zone diet apparently best represents this balanced diet approach and its 30% protein, 30% fat, 40% carbs sourced calories.
Using figures from a study on diets and weight loss in the February 26, 2009, issue of the New England Journal of Medicine (reviewed on the Zone diet):
1. Most people did not maintain their diet but drifted towards the mean ie high protein or low fat were not maintained. These did not loose weight on their diet.
2. Those on a high protein so relatively low carb diet who maintained their protein to give 25% of their calorie intake continued to loose weight.
3. Those on a calorie controlled low fat carbohydrate diet who "drifted" to eating more fat put on significant weight.
Interestingly this is where most cyclists are: low fat, high carb. The high carb I understand raises insulin levels so that once fat is introduced it is quickly passed into the cell by the higher insulin level. Perhaps this explains why Elapid above has maintained his weight and not lost as it appears he should have done.
The reduced carb diet - with calories sourced from protein - keeps insulin levels down facilitating weight loss.
Regarding feer of bonking on a longer ride. Just try it, carry a "spare" sugary bar in case. Your body will store glycogen normally so you should have enough for the first hour or so. Have a balanced meal before going out. During the first hour start to eat. On a day long ride use a balance of protein, carbs and fat earlier on with the reserve of carbs for later. If riding hard you will not replace the calories used in any case. Need to research how the insulin functions.
Thinking this through has just sorted one of my myths. Myth: you need a good ie high carb meal before going out. No. You need your glycogen stores replenished - which is done from what you ate yesterday. You will have enough for an hour stored - most UK cyclists will have ridden 25 mile time trials early morning with only a very light snack, probably cycled there as well. I used to - perhaps that's why I was rubbish. Your body stores for that. To keep going then you need a series of balanced meals, snacks. On a long ride its lots of snacks. We are all aware of carbohydrate loading which is fine for a special event but not for every day or even every week.