Rab,
The first 45 minutes of effort mean the body consumes simple carbs (a sandwich or two eaten well in advance will do). Afterwards, as long as you stay in the aerobic region, your body begins converting body fat into carbohydrates and the latter are used as the fuel. If the effort is controlled (and the motor assistance is ideal for that) -- and stops are being made (which increases the time available for biochemical reactions), my body gets into some kind of equilibrium: fats are converted to carbs and to energy at ideal rate. My last ride meant 3 h 45 mins of pedalling but my total time spent outside was 6 hours. Now, I can say it has been 9 hours between my morning sandwich and the afternoon pizza, and no food intake meanwhile whatsoever.
It is not a recipe for everybody. I'm still obese. My ill legs prevent me from spending too much energy too fast. I'm in agreement with my e-bike regarding how I'm riding and it works in my case. Hydration is a must though.
An anecdote!
I rarely allow myself going into bursts of leg power. I cannot, however, stand the phenomenon of a roadie taking me over when I am on my Vado
Fancy that, I'm pedalling at low speed of 21 km/h upwind in 30% Eco to conserve the battery power; a roadie overtakes me. NO WAY MAN. I'm pressing the + on the remote twice and chase him. Not overtaking him, no, no, no. Just following him. The poor boy sped up to 37 km/h upwind. And he bonked soon
"Nice day to you!" I shouted, while passing him by
And I had to swap the battery soon: something I could have avoided if not his attempt Strava/BLEvo tell me I had a leg power burst of 507 W at some moment of the chase...
Wind/loop/range: Elementary, My Dear Watson
As long as the wind blows from the same direction and with constant speed, it doesn't matter which way you move on a loop route. Riding into the wind in the beginning seemingly reduces your range but moving downwind later compensates for that. Moreover, if you can determine the remaining battery range (BLEvo for Specialized e-bikes is perfect in it), you might be surprised how much of the remaining charge (especially of the spare battery) is left for the downwind return leg. Which often allows me coming back in Sport or Turbo modes!
I'm a mine of fat, the assistance helps my body convert fat into carbohydrates at the best rate possible. Would you believe my weight dropped to 89.3 kg from 89.8 over last weekend? And my current weight was measured after having a breakfast! 
I got passed many times yesterday and there was no way I was chasing them down, I did get one guy back though as he was almost going backwards up a climb, I never saw him again!
