How true is this? Weight is genetically determined?

It can be. It raises the demand for food, inflating prices meaning people on low incomes have a harder time affording it.

Ofc nobody is genetically built to be fat literally, what people mean when they say that is that they may have a really low metabolism (or other factors) due to genetics which on a normal diet will give a fat figure.

I can eat as much as I like and not put on any weight, yet I know some people who nibble a bit of celery and gain 10 stone.

Evidence?

Even then, having a low RMR relative to your anthropometry doesn't offset you from the mean very much at all (I can't get access to the systematic review cited ). If your RMR is so low that it's incredibly difficult for you not to be fat through dietary and exercise intervention, you would be a rarity. There isn't very much variance in metabolic rate amongst humans when you control for anthropometric factors.

Basic economic theory.

Heres the problem mate when I calculate my bulking/cutting calories via using rmr calculators and other tools you will notice that the average rmr for the average person is incredibly low. A typical adult will have a rmr between 1000-1800 calories per day. Consider a man or woman for that matter who work office jobs, 3 meals a day can quite easily reach above 1800 calories and most people eat more than that.
I don't think anybody would argue that exercise + diet = weight loss, I even said in my comment that you may be genetically disadvantaged but calories in vs calories out still applies. My point is that a low rmr is significant because rmr in general is not very high at all. Following a "normal" diet will get a large number of people fat simply because rmr values for most people are quite low. My point is that if we were not to excercise and followed a normal diet or even the RIDICULOUS gda of 2500 calories people will quite easily become fat.

I've rambled on a lot and I think what the OP is trying to say is that some people are disadvantaged when it comes to others due to genetics which is entirely true. He/she probably didn't know beforehand that genetics play a big role in rmr. I don't think anyone however is implying somehow that due to genetics you are unable to lose fat using calories in vs calories out because that is clearly 100% wrong.

Counting you calories really helps, count your calories for say, a week? And then set yourself a daily target and follow it and you'll see the difference..

Generally, weight is put on when you gain more calories than you loose, and you loose weight by loosing more calories than you gain.

What someone "naturally" eats is a highly social and psychological phenomenon: the role of genetics pales in comparison.

Then I went to her house and saw how much they ate, and I was astounded. It was shocking.

Yes. In like very small percentage of the population with odd hormonal issues ( I think there are some cases about Leptin deficiencies around).

lol

Sorry to break it to this thread, but most fat people trying to lose weight do actually understand that this involves eating less.

Your revolutionary arguments will, sadly, not get you the nobel prize solving obesity would otherwise have deserved and undoubtedly received.



Oh really?

Why don't we actually get some evidence injected into this thread. I'll kick us off.

I searched for twin studies and these are the first two i came across: One was on those reared together and showed that monozygotic twins, those that share the same genes, are far more likely to both be obese or both be skinny than dizygotic twins, who share fewer of the same genes. The other was on those reared apart, so if one twin was obese you would expect there to be a circa 10% chance that the other would be as well (population rate). Actually, that chance was 79%. These studies conlcuded that "human fatness is under substantial genetic control" and that 50-70% of obesity is accounted for by purely genetic factors respectively.

I may come back to compare the evidence for diets vs medical/surgical intervention which will answer the truly relevant issue here: what works when tackling obesity. Spoiler: gastric band >>>>> any diet ever.



Why do you assume that any genetic (or indeed "medical") factors are going to be those that affect metabolism? If they exist, it will be most likely to be those that affect appetite: high calorie intake is exactly what you would expect in a family who was genetically predisposed to obesity.



What do you think a genetic component would be affecting if it wasn't hormones like Leptin?

Have you ever tried recording and eating 5,000 calories per day for months on end and documenting your weight maintenance?

Similarly, have your acquaintances ever tried recording and eating only celery for months on end and and documenting their weight gain?

I thought not. If they had, you'd know that this wasn't true.

Something wrong?

Oh really?

Why don't we actually get some evidence injected into this thread. I'll kick us off.

I searched for twin studies and these are the first two i came across: One was on those reared together and showed that monozygotic twins, those that share the same genes, are far more likely to both be obese or both be skinny than dizygotic twins, who share fewer of the same genes. The other was on those reared apart, so if one twin was obese you would expect there to be a circa 10% chance that the other would be as well (population rate). Actually, that chance was 79%. These studies conlcuded that "human fatness is under substantial genetic control" and that 50-70% of obesity is accounted for by purely genetic factors respectively.

Haha, yes I have actually. Not for experimental purposes, but nonetheless. Averaged out at 6000 calories a day or so. Gained 20 kilos very quickly and felt very, very ill.

As soon as I started eating normally (i.e. NORMALLY, i.e. normally, Jesus Christ you know what I mean), it all came off pretty effortlessly within two months.

I also have acquaintances who haven't eaten celery alone for months on end, but who've had vicious eating disorders. Usually ends with a ton of weight loss, a stint at a mental hospital, hysteria + minimal weight gain, then a ton of binging, then freak out, and then around the whole cycle again.

What do you think a genetic component would be affecting if it wasn't hormones like Leptin?

The typical adult must be absolutely tiny then. My BMR estimate via Harris-Bennedict is well into the 2000s as a barely normal BMI'd 6'5".
Keep in mind NEAT, EAT and DIT though, mate. Even a sedentary office worker HSS a much higher TDEE than their RMR.


Note that I said "when you control for anthropometric measures", mate. This means that barring things like height, weight, and drastic compositional variance (fat-free mass and fat mass), there's little variance (+- 200 for 68% of the population. +-300 for 96% at an average RMR of 2000 - I think you'd agree that this isn't very much!). Of course the average adult male and average adult female are going to have hugely different RMRs.