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Comment by jmpetroske | Hacker News Reader

As you gain weight, your base metabolic rate also increases. Having fat means you inherently burn more calories, even if you don’t exercise any more.

Take one person, say they eat 2000 calories to maintain bodyweight. If they start eating 2500 calories a day, they won’t gain 1lb of fat a week forever. As they gain fat, their body naturally burns more calories due to the increased body weight, and eventually a stable weight (higher than their original weight) will be reached.

So yeah if you’re eating 500 calories above your metabolic weight, you’ll theoretically gain weight forever. But in this case your metabolic rate is rising over time, so you would be eating more and more calories per day.

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Fat does not raise your metabolism by a lot (relatively), and tiny changes in diet lead to massive swings in the equilibrium implied by basal metabolic rate formulas. In fact, some formulas do not include weight due to body fat. If you think about it, that fact touches on the idea that your natural weight is being maintained by another body system, one related to GLP-1.

By the way... if humans had to count calories to not accidentally starve or die from overeating, we would not have made it long enough as a species to invent a scientific way to do that. Even the diets of obese or overweight individuals are being naturally regulated, because anyone could physically eat even more.

The potential for overeating chronically has not been possible for most people, in most societies, throughout most of human history. Our current caloric abundance being available to literally everyone in Western society is something unique to the past century.

If you eat 1% fewer calories than you burn every day you will die. You will also die if you eat 1% more calories than you burn every day. Is it possible, really, to suggest that the availability of calories was 100% of the daily requirement of our ancestors, and not 99%, or 101%? That is a level of accident that exceeds belief.

It is incredible to think this precise balance could be maintained by anything other than a closed loop of biological control. How would the wheat on a medieval farm know how much to grow each season? If it was off by 1% consistently, everyone would have died... unless they had a mechanism for satiation.

How do you think our microbial ancestors maintained internal salinity, through the limited availability of salt in the ancient ocean?

> unless they had a mechanism for satiation

It ends up being the opposite. Rather than the body having a satiation response, it controls the metabolism.

If you've ever fasted, you've experienced this. You just don't have the energy to do much other than sit around when you are hungry.

Ancient societies realized this, it's why they'd give out calorie dense meals to their farm labor. For a serf in England, harvest time was often met with a very calorie dense meal. For roman soldiers, they had a diet of meats and cheeses.

I'd also point out that you don't need to have exactly 100% daily calorie intake. You can go a week with just 99% and catch up with 101% the next week just fine.

You will also die if you eat precisely the amount of calories you burn every day.

There exists something called a "feedback loop", something common in biology. You would probably find it interesting, you should look it up.

Basically, it means that if you try to chronically eat, say, 1% more calories than are burned, your body will try to burn more calories to compensate.

I'm not sure I grasp the rest of your comment, could you try again to explain? The wheat farm your ancestors worked did not provide the excess of cheap calories available to the present day American.

That is the intended conclusion of my post, that body fat is obviously regulated biologically, and suggestions that changes in obesity rates are due to the increased availability of food (implying that it was regulated by some sort of precise cycle of starvation in the past) or individual choices (implying that most people are measuring portions and keeping a running tally) are in conflict with that.

You haven't made that point and I disagree with your conclusion.

Your error is claiming some "precise cycle of starvation" is necessary to explain obesity via increased caloric availability.

In reality there were times of excess and times of shortages far more often in past times. In times where there were plenty of items that didn't last you over consumed. By late winter you were getting lean.

>If it was off by 1% consistently, everyone would have died...

You do realize that starvation was a massive killer in the past. Everyone didn't die, but the young, the old, and the weak sure did.

It's not necessarily about BMR - if you maintain a similar activity level as you gain weight, you consume more active calories as well, in almost every activity, particularly the most common ones such as walking.

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