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Comment by kentor | Hacker News Reader

Then the question is why do they eat 3500kcal? The hypothesis is that sugar does not make people feel full whereas fat does, so they eat more. A calorie is not a calorie.

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It would seem that calories don't provide any metric with respect to psychological effect, whether caused by the food or otherwise.

If only people had tried to point this out for many years...

I didn't check the science, but I'm pretty confident that "feeling full" is a matter of volume and not of calories. At least in my personal experience a really dumb and easy way to lose fat without feeling hungry was to eat food with a low calorie density.

Not just volume, but the biochemical process of digestion. For example, food that takes longer to digest has more volume for longer time in your body. There are also complex interactions of chemical secretions to regulate chemistry in digestion.

What foods are you referring to as "low calorie density foods"? I can imagine that most vegetables fit this classification... but why would you state it this way unless you are referring to something else?

I would define caloric density as the ratio of calories to weight. Refined sugar has a caloric density of 3.87 (387 kcal per 100gr), which is quite high. Most vegetables and fruits will probably have a caloric density <= 1. But I would also classify something like chicken breast (1.65) or turkey meat (1.89) as "low" in terms of caloric density. But it's not really about setting a threshold. It's more about being aware of how many calories you actually get per gram of food. It can make quite a big difference.

The goal isn't to "feel full", but to feel full and good for a long period of time. Otherwise, I might as well gorge myself on isotonic water.

I wasn't suggesting that feeling full is the goal. I was just trying to argue that calorie density is an important issue when it comes to obesity and overeating. Eating healthy food is, of course, important. But eating too much healthy food is not healthy ;).

If I had to choose between eating too much healthy food and eating enough unhealthy food, I would probably choose the latter. I think obesity is a bigger problem than poor nutrition.

Why would I eat too much if I eat calorie-dense foods? How full I feel in the long term has little to do with volume and more to do with how many calories I eat and how quickly they are digested.

> The hypothesis is that sugar does not make people feel full whereas fat does, so they eat more.

They still eat about 1500kcal of fat and protein - of which I eat about half the amount.

If you were really talking about feeling full, nothing makes you feel more full than a belly and guts filled with lovely starch/fiber from fruits and vegetables, which an average US eats little if not any.

Yes, they make you feel full... until your blood glucose level drops 1-3 hours later, then you feel very hungry again.

By contrast, if I eat a fat and protein based meal, there is no blood sugar drop to instigate a 'fake' hunger signal, so I don't begin to feel hungry for 4-7 hours or so.

Depends on the person. I can eat stupid amounts of fruit and vegetables... Low-carb is the only way I can not feel hungry.

Of course, the general population does like their carbs to be the refined type.

I can easily get full from starchy/fibrous foods, but then I feel hungry again 1 hour later. Fat/protein rich foods, in contrast, keep me full for 4-8 hours.

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