This is simply not true. You are oversimplifying the issue. As an example, I'd like you to go take a shot of olive oil and tell me you feel fuller than having a cup of steel cut oatmeal with a cup of blueberries. In fact, in 1 shot of olive oil, that's 3 tbsp, which is roughly 360 calories, whereas the oatmeal and berries clocks in around 250 calories. "All things being equal", I just put fat against carbs and the oatmeal just won because 3 tbsp of olive oil will not satiate the way 2 cups of carbs will.

The experiments that measure satiety generally have the subjects eat a measured amount of a certain food, wait a specified period of time, then eat from a buffet wherein subjects may eat pre-measured portions of whatever they like.

In such experiments, certain foods do have a significant impact upon the calories later consumed from that buffet. Some foods are more filling than others. I forget the exact results, other than the one that was surprising to me: whole boiled potatoes were the grand champion of fullness, and 3 times as filling as a calorie-equivalent portion of french fries.

So do your experiment for real, with some volunteers. You will need to make some oatmeal, and pour some oil shots, and have a buffet ready. And you will have to continue the experiment for multiple days, so you can get same-person comparisons for different foods.

Please actually do the experiment before you declare your hypothesis confirmed. For what it's worth, I think it probably would be, but there is always the possibility that we will be surprised by the results.

Naturally, to avoid accusations that your experiment cherry-picked specific foods that are not representative of their fat/carb classes, you would also have to test other foods, like coconut oil, glazed doughnuts, rendered beef suet, dry white toast, butter, and bananas.

But wait. That's still oversimplifying the issue. Boiled white potatoes are three times as filling as plain white bread. If some carbs are more filling than other carbs, how can you meaningfully compare all carbs against all fats?

I guess you can't. The experiment would have to serve isolated food components. Rather than olive oil, serve a shot of caprylic acid, or stearic acid, or DHA. Rather than oatmeal, serve pure starch, or pure glucose syrup, or fructose. Maybe also test the effects of added MSG, aspartame, or table salt.

Everyone is oversimplifying the issue.

I said fatty foods are often more satiating. Your oatmeal vs olive oil competition has nothing to do with what I said.

A higher fat:carb balance than mainstream diets leads to less hunger, because of the satiety of fat when combined with other foods (especially fibre and protein) and mor importantly because of the reduced insulin spike when carbs are reduced.

Lets be real here. Average fatass wont be craving no olive oil tea spoons, but he will get up at 2 in the morning to snort a gallon of blueberries.

The feeling of fullness at the end of a meal is primarily driven by the stretching of the stomach. Which is why people who have their stomach stapled feel fuller faster, and so eat less per meal.

Fat, with its extremely high calorie density, is some of the least satiating food you can eat.

This oversimplifies it a bit, because there are multiple signals and sensations related to satiety and hunger. The mechanics of snacks are different from meals because you will never get "full" from eating snacks, although you may cease being "hungry".

You are oversimplifying it. Calorie density is not the only factor related to satiety.

Blood sugar, insulin, the combination of foods eaten, fibre levels, all contribute to satiety. And in this context adding more fat and less carbs to your diet does increase satiety