I'm no expert but I do like to experiment with my training and nutrition. Since October 27th 2013 I have been mostly on a Low Carb High Fat LCHF Diet.
It's great ! Initially on exercise days I ate more carbs especially on days with long and/or strenuous cycles. Lately I have been reducing the amount of carbohydrates consumed on exercise days.
For example, I would consume around 50g carbs on a non exercise days and up to the government guideline amount of 300g on a workout day. ( WARNING: If you follow the governments advice on Carbohydrate intake, you WILL get fat ! )
Now it's around 150g or less more when exercising. I don't even bother with the essential post workout carb intake. I just have protein.
Lets go straight in and look what I did at the weekend.
A 4 hours cycle over 100km
My effort was averaged out as 139 watts which is Endurance ( Zone 2 ). There's always a wee bit of crossover here depending on other factors.
Anyway after 90min I really should have been tucking away up to 90g carbs to keep my muscles going right ? Well no.
What I had was one scoop of High 5 2:1 Energy Source in each 750ml drinks bottle which lasted me the whole four hours. Each serving ( which is two scoops ) provides 44g carbohydrate. So I only consumed 11g per hour. No cramp, no exhaustion.
Ah, maybe I just scraped home before my carb supply ran out. Well luckily I have been monitoring my blood glucose during this experimental period. If I have two Weetabix ( under 30g carbs ) for breakfast my blood glucose after two hours in around 5.5-5.8 m/mol. Immediately after this ride it was 5.8 m/mol.
Wait a minute, if I had consumed all those recommended carbs I would have done a much better job right ?
Trust me, that's the same ride from three weeks ago. Shows how accurate the Garmin is when you look at the Km. Anyway, I knocked 10 minutes off the ride time and with a lower heart rate and power output than in this one.
Food for thought, so long as you keep your carbs lo :)