A "set point" is just a homeostasis we don't understand yet.

For instance, there's no such thing as a "fat thermostat" in our bodies that we could turn up or down if we could just find the dial. There are trillions of cells in a human body - each with its own energy needs, receptors, signaling molecules, and internal/external concentration gradients, all of which collectively determine what goes in and what comes out. Put a bunch of them together, abstract and simplify their collective inputs and outputs, and we have what we call an "organ". Put a bunch of "organs" together in the right way and we have an "individual".

Result: What some call a "set point" is a stable equilibrium condition between these trillions of cells and their inputs and outputs. The question then becomes "How can we alter this equilibrium condition?"

In the case of body fat "set points", both biochemistry and experience tell us that there are multiple functional and signaling failures, both in and between the cells of the brain and the cells of various body tissues, which can alter the equilibrium condition towards "fat cells store more calories as fat" and/or "make more fat cells".

Conclusion: There are many points of entry to the complex system of interacting feedback loops known as "human metabolism". Calling an equilibrium condition a "set point" is just code words for "We don't understand what's going on or how to change it."

JS

Maybe it's me, but the idea that the body starts to receive the signals about the fat mass resonates with more more than the idea that there's a "set point."

That's two ways of saying the same thing, though. The set point that Guyenet is speaking of is decided upon by the hypothalamus, which is what is receiving the leptin transmissions from the adipocytes. In the case of poor leptin signalling, the hypothalamus mistakes a fat state for a too-lean state and imposes austerity measures to fend off perceived starvation. What exactly causes this to occur is of course a matter of debate, but simply making meals from scratch using Food seems to remove whatever it is that causes the problem over time.

If we're talking about our default wild human set point, then it's about 10% for males and 20% for females. We can have perfect leptin signalling but be at a fat mass above that since the body is far more concerned with defending it from dropping below that point than letting it inch upward. If I got really into chocolate, my fat mass would increase and settle somewhere above where it is currently. In contrast, if I got really into cycling it would drop below where it is now and settle somewhere.

I'm currently uncertain on this topic but I'm definitely thinking about it. I answered another question about set-point the other day with the following:

I no longer believe very deeply in the concept of a set-point.

Here are my reasons:

• In my 50 years of binge eating and yo-yo dieting, I never stopped losing or gaining weight at the same "point" of body fat.
• There never was a "point" at which I could just eat and would stay the same weight--any weight.
• With ancestral eating, I have no urge to eat more even though I've already lost about 40 pounds of excess weight and I'm still losing slowly.
• The longest I was previously in "losing" mode was 4-6 months before exploding into a non-stop binge that took me back to and well past my previous body fat high.

I do believe--and feel I'm now proving for myself at least--that what/when/how you eat does make a huge difference in whether you will quickly regain lost body fat or comfortably maintain your new, lower weight.

My full story is not yet told since I have another 25-30 lbs I'd like to drop. But it must be said that at least 25-30 of my lost lbs have now been gone for at least 6 months and again, I have no urge to change how I'm eating to restore that weight.

My new belief is that it's about your gut flora and metabolism--if deranged, nothing sustainable can happen; if it's healthy, improvement may very well be sustainable.

Then, I saw an article at Getting Stronger about resetting cell receptors which on first read reinforces my acceptance of Dr Kruse's LR protocol. Despite my earlier statements, I think the receptor reset could also be compatible with the concept of set-point albeit one that can be changed.

And inflammation could definitely be part of the interaction between processes.

I find multiple lines of argument in favor of a fat set point. These include (1) underfeeding studies on normal-weight subjects, who regain their weight once they are able to eat ad libitum (2) overfeeding studies on normal weight subjects, who voluntarily reduce calorie intake after the study until they return to their original weight (3) the 'Liposuction and Fat Regain' study described by Guyeynet (4) the rat studies by Kennedy and other researchers as described in Roberts 'What Makes Food Fattening' paper (5) the success some people have when using the Shangri-La Diet, even when consuming inflammatory foods such as canola oil and sugar water for the flavorless calories and (6) the body uses set points for other systems, such as heat regulation.

There are, I think, three theories as to what modifies the fat set point. The first is the flavor-calorie association as argued by Seth Roberts. The second argument is that the brain gets confused when the regulatory logic hears too many conflicting and noisy signals and thus cannot detect when the body carries excess weight. (Extending the metaphor of the set point as thermostat, visualize some prankster who keeps placing a large block of ice in front of the thermostat.) The third is that the brain detects insufficient nutrients and thus orders excess consumption in the hopes of acquiring those nutrients; to overfeed, it must move the set point to a higher value.

I've never really been sold on the idea of a set point for body weight. My own losses and gains have sometimes been driven by depression (hugely overeating), and sometimes by the flip side of that which was self flagellation via under-nourishment, and then the rebound effect of those things.

I've always felt that it's more to do with homeostasis - my body being somewhere on the pendulum but always on the way to somewhere fairly extreme, to restore the balance of whatever I had most recently subjected it to. My personal theory is that natural weight loss is the result of firstly stopping the pendulum from swinging (and inflammation is key there, as well as achieving a healthy general hormone profile), and then applying some kind of calorie restriction and muscle building regimen very gently so as not to start the swinging again.

That's very intuitive, and not at all scientific!