Apples. One small apple is approximately just 32 calories, and even a really large apple that is super-sweet never really has more than 90 – 95 total calories. That makes apple a super low calorie food option when you stick to “just apple” meaning eat it whole and plain, or slice it and eat it plain.
Beyond being a low calorie food, apples have a well-know reputation for keeping the doctor away. Part of that reputation is due to apples containing a flavonoid called quercetin, which is thought to lower the possibility of chronic diseases. Besides that esoteric stuff, apples are full of fiber, vitamin C and a bunch of antioxidants.
There’s about a billion recipes that you can use apples as an ingredient in, some of which are pretty generic, and some of which are pretty unique, using apple as a low calorie substitute ingredient.