Calories in an apple can range between 80 and 120 calories depending on its size.
Apples are a safe dessert or snack to include in your diet, if you are trying to lose weight.
For starters, apples are extremely high in fiber, therefore you stay full for a longer time period. It is a great substitute for bad snacks such as chocolate, cookies, and cakes. If you are feeling hungry and need a quick bite, an apple is a safe choice. Apples are also very filling, due to the fact that they are juicy, leading to satiety (and feeling satisfied/fuller, for longer time periods).
However keep in mind that apples do have sugar in them, having more sugar than most fruits (about 25 g per apple). So, keep your apple consumption to 1-2 per day at most. Also buying organic apples would be a better choice, since non-organic apples tend to have lots of pesticide residue.
Regardless of your weight loss goals, apples are a great, low cal snack, and an excellent source of fiber, which is key to weight loss.