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> Is it genetics? Is it gut microbiota? (E.g. genetics of other species?) If you don't control for portion size comparing people who all have a burger and frie

> Is it genetics? Is it gut microbiota? (E.g. genetics of other species?) If you don't control for portion size comparing people who all have a burger and fries for dinner every night is basically useless, those meals could be hugely different in composition, portion size or how much is left over. Even if dinners are identical, snacking can be thousands of calories a day that you might never see happening. You've also missed what activity they do as well... Two people who both "chug beer and eat greasy takeaways" whenever you see them out can be very different the rest of the time. If one stays slim and one doesn't it's far more likely to be that the former eats smaller portions overall, snacks less between foods and does more activity overall, before reaching for more exotic answers.

inglor_cz 5y ago
Portion size is notoriously hard to control for in freely moving people. If people self-report their foods, they are likely to make mistakes. I know of one study only where the numbers can be trusted, and it was done on prisoners, where every single gram of food that passed their lips was accounted for. They were fed the same diets, but their weight gains varied a lot: https://dm5migu4zj3pb.cloudfront.net/manuscripts/106000/106570/JCI71106570.pdf https://dm5migu4zj3pb.cloudfront.net/manuscripts/106000/1065...
- spiralx 5y ago
  The only place you can see weight gains is by looking at Table I and working it out yourself for each subject, and only the last subject PW had an outlying weight gain in absolute terms but his starting weight was also an outlier - his relative gain was the same as all the others as well. The paper is about how the weight of fat cells changed at different subject weights, not how much subject weight changed for a fixed food size - the only mention of food portions is with respect to ensuring weight was maintained, gained and lost for the different stages. "After desired or maximum obtainable weight was reached" indicates they weren't using weight as the outcome here. The only place you can see the weight gains is by looking at Table I and working it out yourself for each subject, and the relative gains are all very similar: 23.3%, 25.3%, 21.4%, 20.0% and 18.0%. I'm guessing they wanted them to put on 20-25% of their body weight to give consistent and measurable changes to the fat cells.

inglor_cz 5y ago

Portion size is notoriously hard to control for in freely moving people. If people self-report their foods, they are likely to make mistakes. I know of one study only where the numbers can be trusted, and it was done on prisoners, where every single gram of food that passed their lips was accounted for. They were fed the same diets, but their weight gains varied a lot: https://dm5migu4zj3pb.cloudfront.net/manuscripts/106000/106570/JCI71106570.pdf https://dm5migu4zj3pb.cloudfront.net/manuscripts/106000/1065...

spiralx 5y ago
The only place you can see weight gains is by looking at Table I and working it out yourself for each subject, and only the last subject PW had an outlying weight gain in absolute terms but his starting weight was also an outlier - his relative gain was the same as all the others as well. The paper is about how the weight of fat cells changed at different subject weights, not how much subject weight changed for a fixed food size - the only mention of food portions is with respect to ensuring weight was maintained, gained and lost for the different stages. "After desired or maximum obtainable weight was reached" indicates they weren't using weight as the outcome here. The only place you can see the weight gains is by looking at Table I and working it out yourself for each subject, and the relative gains are all very similar: 23.3%, 25.3%, 21.4%, 20.0% and 18.0%. I'm guessing they wanted them to put on 20-25% of their body weight to give consistent and measurable changes to the fat cells.