(Learning Curve) Set Point Theory: What We Know.
For this post, weโre following up my metabolism post with one on Set Point.
Letโs get started with one caveat: thereโs not a lot of good, recent research that has been done on Set Point. In any of my posts, I generally will only use and cite studies published in the last 5 years, which are done on humans. In this post, Iโve had to use a few older studies. I also indicate where rodent studies are cited.
You know when youโre on a diet and then you start eating normally and your weight returns to where it was before you started? Or, when you overeat for a few meals and then you start eating normally and somehow, your weight goes back to around its original number? Thatโs what weโre talking about when we talk about your bodyโs โSet Pointโ weight.
But is Set Point really a thing? What if you donโt like your Set Point? Can it be changed?
Letโs take a look at some basic physiology, and the latest (and not so latest) research, to see whatโs up.
What Is the Set Point Theory?
Set Point Theory was conceived in 1982 by Dr. William Bennett and a researcher named Joel Gurin.
These guys hypothesized that the reason why diets fail so often is because everyone has a set point weight that their body wants to stay at. Itโs generally recognized that Set Point is the weight a personโs body is programmed to be. It also seems fairly apparent that our bodies will put up a fight to defend that certain weight. For all of you who donโt like where your Set Point is right now, donโt despair.
Weโll get into that in a minute.
First, letโs talk science.
The physiology behind Set Point is a very annoying combination of complicated and unknown, so writing about it and making sure I present all of the known and true facts can be difficult. There are many theories behind what Set Point is, and how it happens. Iโve spent hours in the weeds trying to drill this down to something simple – for me and for you. Just ask my husband, who sat through many evenings of me reading complicated Set Point research and talking things out out loud to myself, while he was trying to watch Netflix. Heโs almost an expert on Set Point now too!
Okay, letโs do this.
Your body likes homeostasis, or balance. Your blood pH is tightly regulated between 7.35 and 7.45 (despite what that kooky alkaline diet claims). Fluids and electrolytes are tightly managed, and body temperature is kept between 36.5C and 37.5C. Itโs not surprising then that weight may be one of the things that our bodies want to keep stable, too.
When a certain amount of weight is lost (and I say, โcertain amountโ because this amount is different for everyone), ghrelin, a hormone thatโs made in your stomach, tells your hypothalamus (in your brain) that your body has breached your lower limit of body fat. This causes a cascade of reactions and hormones that do everything from slowing your metabolic rate, to making you hungry enough to quit that diet and put back the fat you lost.
So frustrating! Think staying on a diet is about willpower? Itโs not. Those hormones are super powerful in their efforts to maintain status quo with your weight, and itโs really hard to ignore them. Grehlinโs opposite hormone is called leptin. Leptin works by inhibiting appetite – like on the day after you eat a huge meal, for example.
You might notice that youโre a bit less hungry, and this is leptin working its magic. Leptin signals to the body that youโve had enough to eat, and to stop taking in calories.
This all sounds pretty simple, but itโs not. Unfortunately and paradoxically, people who have a lot of body fat have more leptin; the reason is that they can become leptin resistant because leptin signalling – or the way leptin signals the brain to tell the body to stop eating – gets messed up.
This is thought to cause an increase in hunger – and remember, leptin is supposed to signal the body to stop eating. So as you can see, in people with a lot of body fat, leptin may work in the opposite way.
I could do an entire Learning Curve on just leptin and ghrelin, but I wanted to mention them to briefly illustrate how our bodies work to regulate our weight, and what weโre fighting against when we try and lose a bit (or for some people, gain). Our hormones play a huge part in why itโs so difficult to deviate from our Set Point.
Now that you hopefully have the main idea about Set Point and how our bodies want to keep our weight at a certain level, letโs address some common questions about Set Point.
What affects Set Point?
Thereโs really not a lot of evidence about this, but we have to assume that Set Point is both genetically and environmentally determined.
Pregnancy has been thought to affect Set Point in some women, which would explain why some moms have issues getting back to their pre-pregnancy weight.
We have to remember though, that the work of figuring out whether having a baby has actually changed your Set Point can be confounded by the lifestyle changes that are so common after having kids. This also goes for weight gain or loss in any stage of life: is it our Set Point changing, or is it a shift in habits? Good question to ask yourself.
Set Point may change naturally with age, but that doesnโt mean that you canโt try to override that. Remember: check your environment before blaming weight changes on nature.
Gastric bypass surgery may change a personโs set point, according to this study (rodents), although this study suggests otherwise. Sigh.
Some medications may affect Set Point.
Does Set Point adjust higher with weight gain? (is this why itโs so hard to lose weight with repeated dieting)
We arenโt sure. What some studies show is that with repeated dieting, the hormones are somewhat โsensitizedโ to the โstarvationโ trigger – so theyโre quicker to react to your twentieth caloric restriction than your first.
This would make it harder to stay on a diet for longer, each time you try. This doesnโt mean, however, that your actual Set Point in irreversibly affected (or affected at all).
Some studies suggest that weight gain doesnโt actually do anything to your true Set Point – itโs in there somewhere, and will reappear once your habits change for the better. More on that later.
How do I determine my Set Point?
Thereโs no test to determine your Set Point. If youโve ever been in a place where youโre reasonably active and eating a reasonably healthy diet and your weight is pretty stable for the long-term, thatโs probably your Set Point weight.
Iโve read in a few places that our Set Point has a range of 10-20 pounds, which makes sense.
I know my personal Set Point is 132 pounds. I once went down to 128 pounds by cutting down on my intake, and was unable to sustain that. Up to 132 I went, in about 4 days. If I overeat, I lose weight when I return to my normal diet, and I always land at 132.
How do I get around my Set Point?
This small study suggests that adding exercise to diet can help, and it also seems that losing no more than 10% of your body weight at one time, then waiting around 6 months for your body to adjust may also help to readjust your Set Point. Remember the Biggest Loser? Yeah, they did it the wrong way.
Some people believe that weight loss plateaus arenโt actually your body giving up on your diet; rather, they occur while the body is adjusting a new, lower Set Point.
The recommendation around this situation is that you do not give up on your new eating habits (as many people will at this time, being frustrated at the halt in weight loss); rather, that you wait it out and give the body the time it needs to adjust. Iโm not promoting diets here, but I thought this was really a interesting hypothesis.
If Set Point Theory exists, then why does the population continue to gain weight?
Simple. Because itโs easy to override your bodyโs signals – we do that all the time. Do you sleep every time youโre tired? Do you stop eating every time youโre full? Research shows (and here) that the โrewardโ component of eating easily overrides our hunger and metabolic processes. That means that if someone is faced with an abundance of highly caloric, tasty food and continues to overeat for the long-term, they can easily gain weight, Set Point be damned.
However, if their eating behavior changes and they begin eating less, their Set Point may still be where it was before.
Isnโt it weird that itโs so easy to overshoot our Set Point and gain weight? If the body fights so hard to keep weight ON, why doesnโt it fight just as hard to keep weight OFF?
Some studies suggest (and here) that the body is better equipped to keep weight on, versus keeping weight off. Itโs probably an evolutionary thing – when food supplies were unpredictable, being overweight was a lot better than being underweight.
To understand this further, think of your Set Point weight as a range, with an upper and lower end.
There is a theory called the โDual Intervention Point Modelโ that suggests that the lower end of the Set Point exists (and has existed for millions of years) to prevent us from starvation.
Go over that edge, and the body believes itโs starving (it has no idea whether youโre on a diet or if you are experiencing food scarcity).
The same model suggests that the upper end of Set Point was determined as our risk for predation, otherwise known as keeping you lean to avoid being killed by a dinosaur.
As humans evolved and the risk of being hunted down by predators disappeared, that upper level may have evolved as wellโฆupwards, by a means called โgenetic driftโ.
Sparing you the science talk, letโs just say that over time, some people may have lost their bodiesโ ability to regulate weight gain, and others did not. That could explain why some people gain weight much easier than others, even in the same environment.
Why do some people tend to gain MORE weight back after a diet than they originally weighed?
Thatโs a tough one. In my professional opinion, it could be multifactorial:
Temporary slowing of the metabolism leads to less calories required. When in โfeastโ mode after a โfamineโ, I think people tend to overeat, overwhelming both their hunger and fullness cues (which may also be skewed from dieting), and putting on weight that often overshoots the Set Point and original weight.
That some peopleโs systems can then regulate this weight after regulating their eating and end up back at their Set Point may speak to the above point about genetic drift.
No matter where your Set Point lies, or if you even believe in Set Point, remember these few points, please:
Love your body. Donโt punish it and fight it and try to drive it into the ground because you think youโd be better if you only lost X number of pounds. Thatโs mean, damaging, and unnecessary. Be gentle; move more, eat well, and concentrate on what you do have, versus what you donโt have.
Youโre good enough the way you are, so focus on more meaningful things, like loving and being loved. Live your best life. Iโm a strong believer that when most people eat healthily most of the time and move their body, their weight will land where itโs meant to land. Accepting that weight and moving on with your life can be the healthiest thing you do.
Before you blame your Set Point/body/willpower for anything, take a look at your environment.
If youโre looking to lose weight, Iโm pretty convinced that doing it slowly, combined with strength training, and leaving time for the body to adjust, is the best way to do it.
Everybody is different genetically (unless youโre an identical twin, in which case youโre the exception to this rule), and will respond differently to lifestyle modifications. Try not to compare yourself to anyone else.