As I understand it, there are fillers in some wet food, but not nearly as much carbohydrate filler as in dry food. Dry food can be nearly all filler, sort of meat flavored carbs. Regardless with carb fillers, the experiment breaks down just because obligate carnivores are eating carbs in the first place. That would be like the diet where researchers fed rabbits who are herbivores cholesterol enriched diets and then used those experiments to suggest that people who are omnivores would react like a herbivore.
I'm not trying to be contentious, but metabolism is just (in my opinion) much more complicated than one easy little theory and if people have to experience hunger to lose weight, I can't see any diet that relies on going hours feeling hungry being successful long term.
I personally can see the benefits of three meals a day or even less. "The Warrior Diet" is a book about eating only one big meal a day and he has some excellent information about proteins being recycled and the health benefits of that which are similar to the Calorie Restriction concept that studies have proven increase longevity. It's a good book and I highly recommend it not because it is the only way to lose weight but because of the possible longevity factor.
Intermittent fasting is also very successful for many people. Carb cycling is another thing that works for some people quite well. Even so, I believe one has to go long periods of time without experiencing uncomfortable hunger for any diet to be successful and once again hormones will undoubtedly be involved.
I just don't believe going long periods without eating is the only way for everyone. Books like the Zone which is very successful for many people recommend three meals with two zone snacks. Weight watchers recommends snacks and (works for some people although that is low fat). Nutrisystem has their customers eating six times a day and that works for some people.
I have stalled before, but never gained weight on a low carb diet YET no matter how frequently or how much I ate, but I see on websites that it does happen to people and certainly stalling indefinitely seems very common place from what I have read on various message boards.
My own personal theory (and personal experience in terms of stalling) is that oftentimes people are so vigilant about watching every little carb that they end up cutting out some very essential phytochemicals and antioxidants which makes them feel hungry (because their body is crying out for something they NEED) and they overeat meat (possibly grazing as you suggest) unconsciously trying to get something that is missing.
This seems to happen more to people who have low carbed for a while too and my theory about that is that when people first start low carbing, their body has some nutrients in storage similar to what vegans experience when they first start eating vegan and feel just great even for years because the body stores vitamin B12 for quite a while. Only with low carbers, obviously the missing nutrient wouldn't be vitamin B12 but something else. It also might be a vitamin or mineral that they need to take a supplement for if they have to cut their carbs very low due to messed up metabolisms.
I believe one reason why the paleo stuff is becoming so popular right now is because they include the phytochemicals and antioxidants that people need that many low carbers in their zealous attempts to cut their carbs often leave out of their diets to their detriment.
In his book, the Anti-Aging Zone, Barry Sears quotes anthropological data that compared a large number of existing hunter-gatherer tribes, where they estimated the average protein-to-carbohydrate ratio in neo-Paleolithic diets to be approximately 3 grams of protein for every 4 grams of carbohydrate. That's a whole lot more non-starchy veggies than many low carbers allow themselves to ingest.
I was a skinny child. Too thin. They called me "Skinny Minnie" and "Chicken Bones" all through grade school and part way through high school. They weren't being complimentary either. I remember one girl coming up to me saying, "You know you are really pretty if ONLY you weren't so skinny." She was one of the nice ones! A padded bra is the only thing that saved me from constant ridicule after that. At least I finally had a curve even if it wasn't really mine!!!
Because of school, my meals had to be spaced out until I got home (just as children's meals do now yet we have a childhood obesity problem). That meal spacing didn't keep my best friend from being chubby. We were both the same height, but even so they used to call us "Laurel and Hardy."
However, she was Italian and they ate a lot of pasta in her home and on weekends and they always had desert after dinner every night. Her mother kept a cookie jar on the counter. She got cookies and milk for snacks.
I had a lot of Choctaw Indian in me and my mother had watched her mother die from kidney disease caused by diabetes II. So we ate ... well to be perfectly honest, we ate food like Barry Sears describes in the Zone diet. Small portions of meat and lots of non-starchy veggies. We did have potatoes and beans as well available at every meal, but I really didn't like those foods that much so I ate very small portions of those. We could have all the fruit and nuts we wanted, but dessert was only allowed on Christmas, Thanksgiving, Easter and Halloween. Watching her mother die from diabetic complications made my mother very zealous about keeping junk food out of the house. There was no cookie jar to steal cookies out of! My snacks were raw veggies, maybe half a sandwich, nuts or fruit.
On weekends, I ate non-stop trying to gain weight. People commented that I must have a hollow leg, etc. "Where does she put it?" Anyone who walked in the house would always see me munching on something. But with my mother's refusal to allow "crap" in the house, I had no choice but to eat healthy food. One summer in high school, I worked at a clothing factory, saved my money and made a doctor's appointment which I used my own money to pay for. I begged the doctor to help me gain weight. He examined me and told me I was extremely healthy, had no health problems and there was nothing he would do to try to alter my metabolism.
I cried. He was my last hope. I purchased some product I found in a magazine called "weight on" and tried to choke down those huge chalky tasting tablets but they tasted awful. I tried breaking them up into smaller pieces and taking them like a pill, but the jagged edges from being broken up caused them to stick in my throat which was very painful. Eventually, I gave up on them.
It wasn't until I left home and started eating "sweets" that I started gaining weight. The low carb diet was just becoming popular then. I was a vegetarian at the time I first had a weight problem. All the girls in my office went on low carb. I was in heaven being like everyone else who had to lose weight!!! I lost more weight faster than the other girls even though they watched their carbs more carefully. Everyone assumed I had a faster metabolism (duh), but also I munched continuously on raw veggies in between meals.
Ultimately, I think everyone has to figure out what works for them individually. If you believe in going long periods without eating, I highly recommend the book, "The Warrior Diet" as he does have some good points about the health benefits of that type of intermittent fasting.