Why do I eat more after driving than walking?

Hi

A couple of months ago I managed to reduce weight from 86 kg to 79. I am retired and can spend my day walking to supermarkets in the suburbs, about 4+4 km and buy salad with potato, yams, sweet potato, cassava, tuna, banana, papaya, yoghurt etc and carry home the groceries.

That works for me. I lose about 1 kg per week living like that. When I get under 80 I must start eating noodle soup late in the morning, since I get hungry.

My target is 78 kg but not "possible" without extremely strict life and diet.

I skip wheat. Especially bread. (Easier since I live in Asia and like rice.)

I like to travel. Today I rented and drove a motorbike (with rests for 5-6 hours). I had standard breakfast with yoghurt, banana and at 9 am noodle soup. When I arrived at my destination I was so hungry I had to eat stir fried chicken, veggies, and rice. Big plate. And later two sandwiches from 7/11! Stuff I usually dont touch. Or maybe occasionally chicken/veggies in small amounts. Just had to eat that. I am sure even 2 cans of tuna would have done nothing to that hunger. Now adding banana, youghurt tuna etc.

I "feel like" I need twice as many calories after driving motorbike 6 hours than I do after walking 8 km (and resting etc).

That is not how things ought to work. What have I missed? Sitting on the motorbike will ruin my recently achieved weight loss.

The only way I am sure to lose and keep weight is to live very regularly, making walks and eating what I described above. How do I manage to avoid the hunger that comes with more irregular (and interesting) life style. Irregular life style has always been a killer for my dieting.

I have already gained one kg after a week of travel and irregular life, now weigh 80 kg.