Re: calories burned walking 18 holesOversimplified, weight gain, loss or stability are dependent on the calories in relative to the calories out. Generally, 1lb = 3,500 calories. So, if you consume 3,500 calories less in a week than you burn, you'll lose a pound and so on.
IME, the problem isn't so much with the calculation of how many calories we burn--there's plenty of resources that can give us a fairly accurate figure, rather, it's determining how many calories we consume. Product packaging (those nutritional guides) can be misleading if not read correctly. For instance, I recently purchased a package of 4 hot dogs. According to the package, it listed the calories as 130 for a serving. So, it would be very easy to assume each dog had 130 calories. However, when I read further, the package listed the serving for the entire package as 8. This is an example of how easy it is for people to underestimate how many calories we consume in a given day. How many people would cook only half a hot dog? As it turns out, a single dog has 260 calories.
Taken further, multiply the above "mistake"--the over-consumption of @ 100 calories per day, and multiply it by 365 days in a year. You get 36,500 more calories than you anticipated in a year. Divide that by 3,500 = 10.4. So, all things being equal, you've just gained 10.4 lbs without realizing it.