The challenges of tracking calories in/out

One thing I really struggle with is overeating food that doesn't come with nutrition info, that you cook yourself, or others cook for you. When I'm eating out at KFC it's simple to make an informed decision because they list all the calories on the menu, but how on earth are you supposed to calculate how much is in your homecooked meal?

A while ago I saw an advertisement for a smartwatch, it was either a Samsung or an Apple smartwatch. In the advertisement, the smartwatch somehow records what goes down into our mouths and calculates how much calories it was worth! I wonder if this is for real or just fantasy.

Estimating the amount of calories burned off during an exercise is not as convoluted, but vague nevertheless. How this works is still a mystery to me, and one of my future projects is to understand the science behind calorie tracking (whether it's for food or exercise).

For now I use my smartband to detect my heartrate, input my average heartrate over the duration of my exercise with the Runtastic calculator, and that gives an estimate of how much calories I burned. Which is around the same number I would get if I used the standard calculator (which calculates the calories based on what sort of exercise you did, and for how long).

How about you? Is there any reliable, even proven way to calculate the calories that go in and out of your body? Is smartwatch food analysis feasible, or just fantasy?