Let's revisit calories in, calories out and all that diet goodness (Page 2)

a calorie is a calorie, out side of the body, when food enters the digestive system, this standard unit of measurement has no meaning.

Suppose you have a 13.1 the next day. You carb up consists of:

a) all refined sugar

b) all celery

a) will fuel you for the race, b) will make you fail early, as most of the carbs in celery are fiber, which do have calories, but is not absorbed into the blood for fuel. Also the stomach adn what not breaking down the celery will burn some calories.

This.

Too lazy and late for work to find it now, but there was a "gold-plated" study of studies fairly recently that looked at what was ultimately a very large population and basically showed that the ultimate correlation was to calorie deficit.  There was no statistically meaningful relative effectiveness found in any diet approach (although, iirc, South Beach was sort of ahead of the "pack" slightly).

Don't want to pile on regarding the post citing insulin resistance--as the other poster who responded earlier quite correctly noted, everyone has different factors influencing exactly how efficiently they burn calories, but burn them they still do...or die--but I have a close friend who has cited this factor (and others) as reasons why approach 'X' "can't work for her" and the reality is that she is ultimately not physically active at all (though she actually thinks she is) and drinks too much alcohol (though she has finally been pursuaded by a nutritionist to cut down).  Those sorts of overarching lifestyle issues are ultimately bigger obstacles to weight loss...and are also the obstacles that lie most within our ability to address.

Overestimating the calorie burn from physical activity and overconsumption of alcoholic beverages (which not only tend to be calorie rich, but also have negative effects on the liver's metabolic functions) are two common places where people are in denial mode about why they aren't losing weight, in my experience.  Awful lot of tendency to overlog the former and underlog the latter.

Having lost over 100 pounds, I have done a lot of studying of this. I have also done my fair share of pounding my head against the wall trying to reason with people who just don't get it. In addition to all the ways people fool themselves, they also approach the whole topic as if it's magic. They talk about their body "holding on" to calories as if you can burn 2000 calories when there are only 1500 calories in the pot. (This would be like a car burning 30 gallons of gas when you only put 20 gallons in the tank.)

I do think part of the problem is that people don't understand how much their calorie burn varies from day to day. For a while, I was wearing a BodyMedia FIT 24/7 and it was interesting to see that my basic calorie burn (not counting exercise) could vary by as much as 200 calories a day -- just small differences in activity, how many hours of sleep I got, whether I walked to my meetings that day or called in, how many times I used the stairs -- added up. But people go online, use a formula that may or may not be accurate to say how many calories they burn each day, and then treat that number like gospel when it's just an estimate and it won't be the same from day to day.

Another issue is, while a calorie is a calorie, the types of calories we ingest impacts our metabolic rate. So, if you are insulin resistant and you eat a lot of carbs, your metabolic rate slows. So now, your calories in may be the same, but your calories out is less than if you ate a different kind of food.

I tell people that all these numbers are estimates and what matters is reality. If some formula says that you should be able to eat 2000 calories a day and you gain weight when you do, it's not that you are that special person to whom the laws of physics do not apply; it's that the numbers are wrong somewhere.

This!  Unfortunately our bodies do not obey the formulas.  The formulas were created to approximate an average amongst a large population.  Personally I try to underestimate calories burned to allow for this but I know I'm not always perfect at that.  And unless one measures every little thing that goes in your body it's very hard to get an exact count.  I try to over estimate but I'm sure I miss on a regular basis.