Comment by beagle3 | Hacker News Reader

Comment by beagle3 | Hacker News Reader

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> I imagine you have a more nuanced point, but the statement you quoted is clearly true taken for what it actually is saying.

You are right, of course. Without quantifying (how low is "low calorie"?) these statements are useless.

There was an experiment in Mass General some 15 years ago, in which they were able to get people with similar lifestyle/activity on 1500 cal/day diet. About one third lost weight, one third stayed the same weight, and one third gained weight, depending on how exactly the diet was composed.

Yes, you will lose weight, regardless of diet composition, on less than 800 kcal/day. Is that "low calorie"? "too low calorie"? "moderate"?.

No, you will not necessarily lose weight on more than 800 kcal/day. You probably will if your diet was not specially crafted to make you keep your weight on 800 kcal. When you get up to the 1200-1500 range, there is a non-negligible probability of "accidentally" gaining weight (or at least not lose it) by randomly stumbling on a bad diet composition.

One of Cabanac's (If I'm not mistaken) experiment was able to make rats gain weight for 3 weeks on a diet of water+chalk (caloric value 0) for a while, by feeding them water+sugar+chalk for a while, and then dropping the sugar. Sure, it was water gain - but the calories in - calories out theory fails so miserably in this case (and countless others) that it cannot be taken seriously. (For only 3 weeks for a rat; it might not hold for a human for a few months in similar conditions).

The calorie accounting is an approximation at best, which possibly takes several months to a year to average out reasonably, whereas a lot of the research focuses on results over 3 months or less.

I'd bet a fair amount that your Mass General study used self reported calorie intake.

800kcals a day is typically enough for a 100 lb person to lose nearly a half a pound of fat a week. That's low calorie by most people's measure. Certainly mine at 200lbs

When most people are talking about 'losing weight' they mean losing fat. At least losing actual body tissue. Anyone can gain or lose 10% of their body weight in a few days by controlling for carbs. But its just water.

Try to ignore rat studies if you possibly can. Their metabolism, particularly their capacity for denovo lipogenisis is very very different than that of human beings.

> I'd bet a fair amount that your Mass General study used self reported calorie intake.

99% of nutrition studies are, but this one wasn't. I can't find the reference now, though.

Personally, I've been on a ~1200kcal/day diet for years (for some of that time, I did very detailed tracking), and stayed at my 220lbs. Which, of course, makes no sense, and it didn't to my girlfriend at the time who was an MD - so she decided she'd show me how wrong I am by eating the same as me. She lost weight quickly and started blacking out (apparently some form of malnutrition) within a few days, and stopped after a week with a SEP field resolution ("Contradicts everything I know, so I'm just going to ignore it").

Then, 12 month ago, on essentially the same diet, I started gaining weight - slowly but surely. And then I decided to cut away wheat, and lost 30 pounds within a month. (In retrospect, I also noticed that my gain weight coincided with going from pure-egg protein powder to egg-and-wheat protein powder).

There are about a thousand more variables than calories, and the body can change its efficiency.

Ignore the rat studies if you like, but cabanac has similar experiments with humans -- basically, people fed through a nose tube lose weight almost independently of the amount of calories you put in their stomach. Body just doesn't use the food unless proper signaling (apparently, scent related) happens.

So, for the uninformed peanut gallery, beagle3 is just plain wrong. Probably not intentionally, he's likely also fooling himself. But you locked him in a room and measured his food for him and really only fed him 1200kcals per day, even at a fairly sedentary level of exercise, a 220lb man would lose a lot of fat mass over several weeks. And no beagle3, human bodies tend to be very greedy with calories and do a good job absorbing them regardless of what you smell.

What likely happened is that reducing carbs reduced beagle3's appetite and he ate less. Unless...

...unless beagle3 has a magic body that has never once been seen in any controlled experiment. But he probably does, since every dieter who has problems believes they have a special body that science can't explain. So they buy a book and a program from someone who tells them what they want to hear. And if their guru is on their game they sell very very expensive supplements.

Because its a well known scientific fact that the first law of thermodynamics applies to everything in the universe except a disgruntled dieter.

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