Confused about calorie needs

Question
Hi.
Thank you so very much for offering such a wonderful service.
I have been absolutely losing my mind over this.
I am 6? 150lbs 30yr old male.
I am looking to see exactly how many calories I need.
I exercise 6 days a week.  Consisting of running a total of 15-25 miles a week,  riding the stationary bike for 2 hours, using the stair stepper for 45 minutes and lifting (not very hard, as I am quite thin it is hard for me to lift weights) for 1.5-2 hours.
Also, I enjoy taking walks whenever possible in the afternoon/evening.  I estimate the total mileage is around 2 or 3.  Maybe?
I am tied to my desk at work, but take advantage of every second of down time to stand and stretch.
I have been searching and searching to the ends of the internet and have received such various feedback on the exact requirements for myself that I am pulling my hair out.  Thus, I sought help via asking a dietitian/nutritionist.  I have since found you and am pleading for help.
I am so very confused, as many of the online calculators say I need around 2600-2700 to maintain.  I eat exactly that ( Roughly 2700-2800 a day).  I do not really have a goal of gaining or losing, I just want to be/stay healthy.
What I am very frustrated about is how much I feel like I eat.  I read, hear, and see others saying they eat around 1500 calories a day.  How is this possible?  These people I know that eat around that total are not overweight, but they are larger individuals.  I do not understand.  I eat a large amount of food and am thin.  Yes, I exercise, but not that hard.  I see lots of people at the gym going harder and longer than myself, and they are larger than me.  They are the same people that state they eat the lower calorie diets.  How is this possible?
I am so very frustrated and confused, I just want some clarification for my own piece of mind.
Any help at all anyone can provide would be amazing.
Thank you so very much for providing this wonderful service.
I cannot wait to hear back from someone soon!

Answer
Dear Marc,

You are not alone in your confusion about calories. First of all, I suggest that you read these articles explaining what calories mean and how they work.

Calorie theory critique

Body weight math

What do you know about calories?

The many types of calories

Calorie intake on low carb diets

As to the practical applications to your particular case, contact me when you read the stuff and maybe you will formulate your question differently then.

Tanya Zilberter

1. Prev:Getting fit
2. Next:Diet and Healthy Safe Weight Loss