Here's the technical aspects I see no one talk about:
(1) Air fryers have much higher air flow than a convection toaster oven and the chamber is more aerodynamic resulting in better air flow around the food.
(2) Air Fryers have a basket, convection toaster ovens may or may not have one and buying an aftermarket one is surprisingly not cheap.
(3) Air fryers have a hair-dryer design, with a fan blowing onto a heating element. The convection oven has normal top and bottom heating elements with a fan blowing the air around on the side.
I find that the air fryer does do a better job at reheating (refrigerated or frozen) fried foods such as tots, fries, fish sticks and chicken tenders. But the trade off is that it's not as good at toasting and roasting things like waffles, bread, quesadilla, pizza or vegetables.
(disclaimer: I don’t have one, but America’s test kitchen/cooks illustrated tend to be pretty reliable with their advice I find…)
edit: see also https://www.americastestkitchen.com/videos/4115-air-fryers
Edit: Suppose I should mention I have an in-wall convection oven in my kitchen as well. It does “fine” but frankly sometimes I’m cooking for a large enough group that I need both the convection oven and the Instant Pot air fryer going at the same time. Plus, my convection oven takes forever to come up to full heat, so often the “Air fryer” is a better choice in terms of capacity and time.
Should I expect to use an 'air fryer' to do things I can already do with other tools—like toast bread or roast/bake something small, even though none of those is 'frying'? What are important considerations / differences relative to the small convection oven I already have?
If air frying is a fundamentally new cooking technique, then I may not be able to apply a wealth of cooking knowledge & intuition when using it, other than basic food chemistry. If it's a rebranded convection oven, then I can decide if a different form factor is worth it for things I already know how to do.
Does that make sense?
These are exactly the features that make it so effective for me. I love convection ovens but the air fryer is almost always more convenient with better results for the kinds of foods I'm cooking with it.
(And is the evidence about coconut oil conclusive? Last I heard it may or may not be good.)
Also, the amount of oil you avoid by moving from deep frying to air frying, depending on portion sizes, can be much more than a tablespoon.
(Obviously, metabolism is more complex than this. I'm discounting the effects of adding fat on satiety, absorption rates, etc.)
This is Hacker News. Of course he's completely sedentary