Is Your Weight "Set Point" Set in Stone?
Basically, your set point is a biologically determined point at which your body "thinks" that it can function optimally, similar to the point that the 123Diet guidebook refers to as a "weight memory."
This point can be very different for different people; your natural weight set point can be affected by genes, your mother's diet during pregnancy, and the nutrition you get during your earliest years. Your set point can also be altered by puberty, pregnancy, menopause, certain medications, stress, brain damage, excessive exercise, or, perhaps most infuriatingly, just by slow and gradual weight gain over time.
In set point theory, the body regulates your weight the same way a thermostat might regulate temperature, by encouraging you to eat less if you are above your "set point" and to eat more if you are below it. This is part of why it's so hard to keep lost weight off, and why some naturally lean people can't gain weight no matter how hard they try! (Yes, I hate them too.)
These compensatory mechanisms, however, err on the side of encouraging us to have too much fat over too little; until very recently in human history, food shortages were far more dangerous to us than food surpluses. So while it's fairly easy to drive one's set point up, it can take a lot of effort to drive it back down!
In the case of extreme obesity, experts theorize that our bodies' natural set point is overruled by a combination of "thrifty genes" and an environment that encourages a sedentary lifestyle and provides us with abundant access to addictive foods that can damage our metabolism and wreak havoc with our natural system of hunger cues.The best way to reverse this metabolic damage is by eating healthier foods and reducing your sugar intake, which will in turn reduce your insulin levels and increase your body's ability to burn fat. It may also necessary to cut out most artificial sweeteners, which condition you to crave sweet tastes and can have negative effects on your microbiome.
For better or for worse, the longer you remain at a certain weight, the more likely it is to become your new set point. So if you've lost a lot of weight, you may have to put substantial effort into your maintenance for years before you can feel truly comfortable at your new size, but it can eventually happen. On the other hand, if you're at a size you'd rather not be right now, maybe you ought to get yourself on a diet sooner rather than later!
Set point theory also partially explains why you will likely lose weight fastest towards the beginning of a diet before eventually finding that your weight loss has slowed or even stopped altogether. The more weight you have to lose, the longer you can diet before approaching your "set point," which is why some dieters find their weight loss easy and predictable until they get to those infamous "last ten pounds."
If your weight plateaus while you're already eating at a relatively high calorie deficit, you shouldn't start eating less, which will only slow your metabolism further and potentially lead you to gain more weight in the long run. Instead, you may want to look into doing more exercise and choosing foods that can help boost your metabolism.
One way to avoid plateauing altogether may to lose weight more gradually. Since your body usually starts to fight back once you lose around ten percent of your body weight, a 200 pound (90 kg) person may want to start by losing only 20 pounds (9 kg), then giving their body some time to adjust before starting their next round of aggressive dieting. A 150 pound (68 kg) person, on the other hand, might want to set a reasonable initial goal of around 15 pounds (7 kg).
The good news about this strategy is that even a five to ten percent decrease in body weight can have a significant effect on your risk of certain health conditions, including heart disease, diabetes, inflammation, and obstructive sleep apnea. As long as you maintain your healthy habits while you're focusing on maintaining your weight rather than letting yourself slide back into your sugary ways, you could do your body a lot of good even without getting any thinner right away.
Finally, if you've tried every weight-loss trick in the book and still can't get the scale to budge any further, check your BMI (Body Mass Index). If it's under 25, you are no longer technically overweight as traditionally defined for health purposes, and have probably reached a healthy set point for your body.
Though you may still wish to be a smaller size for personal or aesthetic reasons, it's possible that continuing to fight against your body's natural inclinations may do you and your metabolism more harm than good. Making peace with your current weight or expending more effort to change your body's composition via exercise may be more reasonable options.