Your basal metabolic rate is not much different from the guy next to you of similar age and weight, barring some extremely rare circumstance. I don't know what to tell you, other than that.

> Two people consuming the same quantity of energy and exerting the same number of joules on exercise equipment do not see identical or even necessarily related physiological effects. There are many, many factors - other nutrients, genetics, timing, the distribution of work over time (short intense exercise vs. long less intense exercise, etc.) and they all matter.

Exercise is probably the least important part in proper weight maintenance, because of all the reasons you listed. Most people promoting the 'calories calories calories' mantra will tell you the exact same thing.

Your diet, and specifically how much you're consuming (regardless of carbs/fats/salt/etc.) is critical, the rest is secondary.

> There are skinny people who have never been inside a gym. There are fat people who work harder than you. Obviously you can still influence your outcomes, but "energy out >= energy in" is a gross oversimplification.

Not really. Those skinny people are eating less (in aggregate) than the fat people, again barring some very rare metabolic condition. Guaranteed.

This is clearly some genetic thing - I was the same way; my nieces are the same way (one getting married in a size 2, that had to be taken in). Eats ice cream by the quart, as often as she can get it.

Folks, denial isn't an argument, so please say something instead of just clicking down. I've just mentioned all this not as a straw-man but because a claim of an absolute (Everybody who is skinny isn't eating much) can be disputed by a single counter-example. That's all.

>Not really. Those skinny people are eating less (in aggregate) than the fat people, again barring some very rare metabolic condition. Guaranteed.

Take a look at http://en.wikipedia.org/wiki/Basal_metabolic_rate#Causes_of_... to find actual measured differences. The #1 cause of differences in BMR is lean body mass. A body builder will therefore have a higher BMR than a fat guy of the same height and weight. Energy spent on short intense exercises that bulk you up will have a bigger impact on your weight than long less-intense exercise that doesn't.

It turns out that we can explain about 3/4 of the difference in BMR through known factors such as these. But 1/4 of the normal variation comes from unknown factors, and that variation can easily leave an individual using 10-15% more or less energy than would be otherwise expected. This is a pretty big difference!

Furthermore even if you were right about all of that, you would STILL be wrong! Among the other potential effects of exercise is appetite suppression. So if your goal is to eat less, the easiest route might be 45 minutes per day on a treadmill, and then paying attention to your appetite.

But about BMR: Lean body mass between two people of same height and weight can certainly make a difference, but people tends to overestimate how much of a difference it will make assuming weight stays relatively similar.

(Note that difference in lean body mass certainly can have very substantial effect when you ignore large differences in weight because that opens the door for much larger variations in lean body mass, but note that bronbron was explicitly talking about similar weight)

I'm an amateur power lifter. My lean body mass after abut 10 years of exercise is about 15kg higher than when I was pretty much the same weight but fat. If I'd stated lifting younger (I was about 30) or used steroids, or spent more time with a trainer early on learning the right way to train, I might have added substantially more, but people tend to overestimate how much muscle you can realistically add. My current weight and performance means I'm an advanced lifter, within the top 10% of gym goers easily.

I often see people think they need to add on huge amount of calories when they start exercising, but that's rarely true. My average calorie intake to maintain my weight including what I burn during 3+ intense weight sessions a week, at a weight of 106kg is about 2400. That is not estimated, but measured by tracking weight + intake in detail over periods of weeks. Subtract my exercise and some other activity, and that easily puts an upper bound on my BMR of 2000kcal/day, most likely more like 1800. A lot of kids freak out when they see those numbers, because they've looked at stories about steroid filled freaks of nature that eat 5000kcal+ a day and think you couldn't possibly add muscle at my intake...

Schwarzenegger during his career as a bodybuilder was about my current weight when competing several seasons (he was heavier when he was a power lifter), but he probably had another approx. 15kg of lean body mass where I still have excess fat (if only I could magically transform my stomach fat and shift it to my chest and arms..).

That pretty much bounds the lean body mass difference for someone at around my current weight to around 30kg. I'm sure you could find someone with less lean body mass than I had when I was untrained if you went looking for really sickly people, but I was weak; you couldn't find many with more than Arnold without bumping the body weight up)

It's fairly normal to estimate about 12kcal per kg of extra lean body mass. The difference between untrained me 10 years ago and trained me today then adds up to only about 180kcal. And between untrained me 10 years ago and Arnold, about 360kcal/day.

Of course that's not nothing - 360kcal is a small/medium meal if you're careful. But very few find themselves towards the top of that range, so a difference that large at the same weight is likely not common (I was totally untrained and extremely sedentary when I started training), and if you do, your exercise will tend to dwarf the difference in basal metabolic rate. E.g. one of my workouts burns in the 500kcal range; I end up burning about 200kcal more per day on average. A top level bodybuilder will spend 3-5 times as long in the gym as me every week, maybe more (and on top of that, you are highly unlikely to get remotely close to Arnold level physique without steroids). But note also that this is before secondary effects: When I exercise, I am generally more active outside of the gym because I feel more energetic. I'll be more inclined to walk to/from the train station instead of taking the bus, or take a walk during lunch hour.

You can certainly find "mass monsters" amongst steroid using body builders today that have lean body mass way above that (e.g. Ronnie Coleman), but they are few and far between, and again the amount of exercise you'd put in makes the BMR relatively irrelevant.

if it were a small % of overweight people you might have a point, but the high % of overweight people in US in particular is certainly because of calories consumed >> calories burned.

i think the real tragedy is people looking for magical formulas, or giving up because 'its genetics'. further proof of that is that just about any dieting regiment works, the issue is that most people dont stick to them.

You say that like genetics has nothing to do with whether someone will stick to a diet or not ;)

Kidneys do not turn sugar into fat.

restrict carbs to a minimum and without a diet they will slowly lose the weight

That is a diet. They will lose weight if they consume fewer calories than they spend.

This nonsense is a great example of the awful ideas that people have about dietary science, and how poorly the truth is being communicated.

Make fat feel guilty about their weight and get them to continue eating sugar and corn syrup has only made the epidemic bigger in the last decades.

Controlling what you eat is the definition of implementing a diet, so doing that is not "without a diet".