I just finished watching the Documentary "10 Things You Need to Know About Losing Weight" (it's on youtube) and it was one of the most interesting documentaries about weight loss I have ever seen. The 10 tips are already things that we know and try to follow, but they scientifically/medically prove each one.
At one part they had a woman, who said that she ate healthy and exercised but had been over weight all of her life and, she felt, her metabolism was just naturally slow.
They did metabolic testing and her metabolism was normal. So they had her record what she ate for 9 days. The first 4 days she video recorded what she ate at the end of the day, and the last 5 she wrote it down immediately after she hate. They had her drink something (I forgot what it was called, but they explained what it was and how it worked) which would allow the scientists to see the amount of calories she ate by testing her urine.
On the days that she video recorded at the end of the day she underestimated her calories by 60%. On the days she recorded it immediately after she ate, she under recorded by 43%. I think she just wrote down exactly what she ate, and the calories were calculated by the nutritionists.
Wow! I just find all of the science behind why some of us have such trouble losing weight absolutely fascinating! If you guys have a spare hour you should definitely watch it.