Sugar has the convenient trait of being essentially a flavor, so all that's needed is to trick chemical receptors on the tongue with something that's nontoxic and either not bioavailable or very high intensity relative to sucrose. Fat ends up affecting flavor, mouthfeel, and food traits (e.g. water retention, bulk) - and a lot of those roles are inherently tied to fat volume.
Safe, bio-unavailable fats already exist, more or less, in the form of fatty alcohols. They can cause minor irritation to the liver, but nonlinear long-chain fatty acids are safe enough that we already use them in food as emulsifiers. Wax esters, which bind fatty alcohols to fatty acids (i.e. normal fats), are also poorly digested and extremely fat-like. Escolar and oilfish are notable as fatty fish with wax esters making up almost all of the fat.
Unfortunately, that 'volume' issue now comes home to roost. Wax esters in low doses (e.g. orange roughy) are fine, but in high doses (e.g. escolar), they tend to cause stomach pain and bowel issues - not because they're toxic, but because they simply aren't digested. Other replacement fats like Olestra (once FDA approved as a fat substitute) have the same problem: they simply come out in the same form they went in.
To replace a significant portion of our "fat experience" with artificial fat means we need something which is similar in the mouth, low calorie and cholesterol, but also digestible. The best options we've found are either variant fats with lower absorption and calorie density, or other-macronutrient substances which serve only some of the same roles, like pectin or whey. Those, again, can lower cholesterol but can't do much better than half the calorie density of fat.
I'm not sure what artificial fat on the level of artificial sugar would mean. It would, I suppose, have to be something which is digested sufficiently to excrete without deriving energy or other components like cholesterol. And in an Algernon Argument sort of way, we probably shouldn't expect to find the body digesting very many compounds it derives no benefit from, so "somewhat better" is probably all we can hope for.
Sugar has the convenient trait of being essentially a flavor, so all that's needed is to trick chemical receptors on the tongue with something that's nontoxic and either not bioavailable or very high intensity relative to sucrose. Fat ends up affecting flavor, mouthfeel, and food traits (e.g. water retention, bulk) - and a lot of those roles are inherently tied to fat volume.
Safe, bio-unavailable fats already exist, more or less, in the form of fatty alcohols. They can cause minor irritation to the liver, but nonlinear long-chain fatty acids are safe enough that we already use them in food as emulsifiers. Wax esters, which bind fatty alcohols to fatty acids (i.e. normal fats), are also poorly digested and extremely fat-like. Escolar and oilfish are notable as fatty fish with wax esters making up almost all of the fat.
Unfortunately, that 'volume' issue now comes home to roost. Wax esters in low doses (e.g. orange roughy) are fine, but in high doses (e.g. escolar), they tend to cause stomach pain and bowel issues - not because they're toxic, but because they simply aren't digested. Other replacement fats like Olestra (once FDA approved as a fat substitute) have the same problem: they simply come out in the same form they went in.
To replace a significant portion of our "fat experience" with artificial fat means we need something which is similar in the mouth, low calorie and cholesterol, but also digestible. The best options we've found are either variant fats with lower absorption and calorie density, or other-macronutrient substances which serve only some of the same roles, like pectin or whey. Those, again, can lower cholesterol but can't do much better than half the calorie density of fat.
I'm not sure what artificial fat on the level of artificial sugar would mean. It would, I suppose, have to be something which is digested sufficiently to excrete without deriving energy or other components like cholesterol. And in an Algernon Argument sort of way, we probably shouldn't expect to find the body digesting very many compounds it derives no benefit from, so "somewhat better" is probably all we can hope for.