I know a lot of people who feed their dogs once a day with 0 issues. I’ve read quite a few articles now on fasting dogs and how good it is for them and their systems. I would think if you fed once a day with no issues, I wouldn’t think it would be a problem.
Now I know dogs and human systems are very, very different, but I know if humans only ate once a day, they can gain weight (as in body goes into fasting mode), but only for so long. Obviously if they are being starved, they will eventually lose weight. But if they eat 1 big meal a day, they can actually not lose any weight (even if consuming less calories) and its better to have several small meals a day (I’m not a nutritionist but worked with 2 different trainers when I was in body building and worked on meal plans, weighed my food for years, when and what to eat etc as I also had a lot of body fat to get rid of). I wonder if it would be similar to dogs if they only received one meal a day, as in they could possibly gain weight? My mother in law who feeds all of her 3 breeding dogs 1 x a day does have dogs on the pudgy/heavy side. They are also farm dogs but are quite inactive. They prefer the indoors on a lap though lol! And are kibble fed (as in high carbs which I find is also hard for a dog to lose weight on since they burn carbs off last). My girl is also really hard to get out of bed in the morning and has a hard time waking up to eat. But due to her breed and potential issues, her breakfast is important. She loves her dehydrated Smack dog food in the mornings, raw bones in the afternoon and a raw meal in the evenings and it has worked really well for her for the past 1.5 years.
I actually do give my giant breed dog as many small meals (4 after her gastropexy surgery which was tough!) as possible through the day and do not exercise her 1hr before or after a meal, in case of bloat, even though her stomach is now tacked, she can still bloat. Her breed (Greater Swiss MD) can also get lick fits (http://www.gsmdca.org/wp-content/uploads/2019/09/LICK-FITS.pdf ) if their stomach is empty, have bile vomits, so most people who own the breed also feed several meals a day, plus a bed time snack and always have bread, tums and bloat buster (simethocone) on hand just in case as it can be a common occurrence within the breed. Luckily my girl has not had any of these lick fits.
So as so many have said, do whats best for your dog in front of you as it can really vary from breed to breed!