And the difference between the top 5% and bottom 5% of the outliers was around 30% (which means for a 2000kcal average BMR, the bottom needed only 1700 and top 2300). This, in my opinion, is not enough for people to tout slow/fast metabolism for weight gain/loss as most people won't fall into the top/bottom 5%.

Edit: for reference 300kcal is about what you'd burn off with a 4 kilometer run.

What I'm saying is that I really doubt the most of the people that are overweight/obese are eating according to what a BMR calculator says and because of slow metabolism they are getting fat. Also, body uses more kcals per day than BMR, you also have to take in account the activities per day.

Using Harris Benedict formula:

If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2

If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375

If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55

If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725

If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9

The thing is, most (and I know this is pure observational) people I know that are overweight/obese either underreport calories (they say they eat just a salad, but forget the 5 table spoons of dressing/olive oil they season it with) and over report activity levels (jogging is not moderate exercise!).

I know it isn't data, but my mother and my mother in law are some of the people that most annoys me related to this. They swear they don't eat treats (I see them eating on average 2-3 cake slices or ice creams per week) and they say they only dine salad (but include 2 loafs of bread and a lot of oil based seasonings) and complain they don't lose weight. And this is what I see in about 90% of the people I know that are overweight. Maybe it is cognitive dissonance/bias but some people just believe they can't lose weight, so they bend the truth to support that idea.

ps: sorry to be such a 'asshole' related to this. Fitness and nutrition is a passion of mine, and I hate when people use excuses for their lack of progress, or attribute 'genetics' or 'luck' to my progress (sure, they don't see me at the gym 1.5 hours every day working my ass off, or not eating bread for months at a time.)

And you shouldn't use a slow metabolism as an excuse for accepting a certain state, maybe that's easy for you and me to say as we both seem to be lucky enough to be healthy.

But since you can alter your metabolism it can be a useful tool as part of weight loss. Do weights, increase muscle mass, increase metabolism, lose weight. In terms of time spent weights are very effective as well - 3-5 workouts of 45mins per week is plenty.

And not to try to be the naysayer, but the effect of muscle on calories burned at rest has been quite the myth floating around. Check the references at the bottom of http://www.lanimuelrath.com/blog/calories-burned-by-muscle-v... and you will see that 10 pounds of extra muscle will burn at most 60-70 more calories than fat at rest.

Apart from that, I agree, do weight training 3-5 days a week. move around, eat healthy. That should be enough to at least get you to the normal weight range.

Of course, anyone who has dieted long term knows that that's not the whole story. You might cut your calories in half and still plateau within a few months.

I don't think cutting your calories in half would result in a plateau within a few months in most cases. That's quite a major reduction, pretty much a starvation diet.

The initial claim was about 300 kcal more than you need, though.

My experience suggests plateau happens every time, without regard to the type of dieting done, unless it's quite literally a starvation diet. The only time I've manage to lose more than 100 pounds was on a diet of about 400 kcal a day. Reducing my diet from about 3500 kcal/day to half that (by the simple method of not eating every other day) worked really well for about two months, and then plateaued; total reduction, about 50 pounds. I've resigned myself to losing in bursts and concentrating on not putting much back on in between.

Of course, my sample size in number of people is low... :)

Losing in bursts doesn't sound like it would be a healthy option for the rest of your body as well.

Do you include exercise at all? From what I've researched, and what trainers have told me, weight training is the most effective way to lose weight - when combined with calorie monitoring and some cardio.

Losing in bursts is probably less healthy than losing steadily, but more healthy than not losing at all. :)

The reason: I avoid sugars and all kinds of flour.

With keto diets you lose weight faster the more you eat.