Ok, today I’m going to be discussing a pretty unpopular, unsexy yet necessary topic: weight set point theory. In the current diet culture we live in that’s obsessed with the thin ideal, dieting and body dissatisfaction, I think it’s important to raise awareness to the fact that body weight is not something we have as much control over as this culture wants us to believe. I mean, if dieting was really the answer, then how come 85-90% of dieters regain the weight during a period of 1-5 years? Why do fad diets keep popping up to replace the ones before them that clearly didn’t work? If you want to learn about how your body is actually wired for survival (ie, living) and not for weight loss, keep reading to learn about what is the set point theory and why obsessing over weight is useless and harmful.
What is the set point theory?
The definition of set point theory with regards to body weight states that your body is genetically and biologically programmed to stay within a predisposed weight range. Kind of like a thermostat. This weight range is where your body functions at optimally. There are many factors that influence your body’s set point for weight, including:
- Body composition
- Body frame
- Environmental factors
Therefore, the set point theory proposes that your weight set point is as impossible to control as your eye, hair and skin color. This weight can range from 10-20 pounds, and it’s where your body likes to stay when not under conditions such as :
In fact, your body interprets dieting as being under starvation conditions, which is why it eventually adapts to function at a lower metabolic rate, which is one of the reasons long term weight loss is so difficult to achieve. This is actually a protective mechanism, as the body fights against the threat of not getting enough energy.
As this research paper explains it: “Weight loss is accompanied by persistent endocrine adaptations that increase appetite and decrease satiety, thereby resisting continued weight loss and conspiring against long-term weight maintenance”. What it’s referring to is weight maintenance that is not your natural weight.
What is natural weight?
Natural weight is the weight your body will maintain (and not resist attempts to change) with normal eating and normal exercise. It’s the weight your body likes to be at when you’re not restricting food and/or over exercising. Natural weight is the one that allows you to function well mentally, physically, and emotionally. It’s effortless to maintain (although it will naturally change with time-which is normal) and is free of food and body obsessions. In fact, it’s pretty much useless to prescribe a certain amount of weight to an individual, since it’s their very individual factors that actually have a much bigger say in what they will weigh, versus any conscious attempts to change it. Ok, so why is it so difficult/ nearly impossible to change one’s weight? Let’ check out how this works…
So how does the body regulate weight?
In order to understand how the body regulates the weight range it likes to be in, let’s take a look at the three main models of set point theory. You’ll see that although they may have their limitations and differences, it appears that the set point theory is real.
According to a recent paper on the set point theory of weight, “Three different models have been proposed, with a “set point” suggesting (i) a more or less tight and (ii) symmetric or asymmetric biological control of body weight resulting from feedback loops from peripheral organs and tissues (e.g. leptin secreted from adipose tissue) to a central control system within the hypothalamus. Alternatively, a “settling point” rather than a set point reflects metabolic adaptations to energy imbalance without any need for feedback control. Finally, the “dual intervention point” model combines both paradigms with two set points and a settling point between them”. Don’t worry if this sounds confusing. I’ll explain it better now.
The Set Point Model
The set point model is based on an active feedback mechanism. It proposes that the amount of body fat (which is really stored energy) is influenced by:
⦁ Intake of energy (calories) and
⦁ Expenditure (using) of energy
The set point model proposes that this mechanism is encoded in the brain. It seems that stored fat in the body may produce a signal that’s sensed by the brain. The brain then compares this signal to a target level of body fatness. If there’s any difference between the signal of the actual fat stores with the genetically determined target weight, this will trigger changes in food intake and/or energy usage in order to bring the levels of body fat back to where the body wants it to be. It is proposed that the hormone leptin is the central player in this mechanism, although other hormones and physiological processes are also involved.
This set point model proposes that changes to this system, trough dieting or overeating, may cause a change in weight (loss or gain), but once normal eating is resumed, body fat tends to return to its original level. This model also proposes that the body defends a certain level of adiposity, which may “explain the common phenomenon of weight regain following acute weight loss and the failure of dieting as a strategy to promote prolonged weight loss”. It also helps explain why it’s harder to lose weight over time after chronic dieting, as the body tries harder to “hang on” to its fat (energy) stores.
However, as this paper points out , this model does not fully explain the significant social and environmental influences on body size, food intake and physical activity. It might also be an oversimplified model as more factors become known which are able to influence body weight and body composition. Which brings us to another set point theory model.
The Settling Point Model
This model is based on the idea that both your body weight and your body fat levels will “settle” at a given point based on the environment. Lifestyle, diet, activity level, even socioeconomic level determine your level of body fat. What this means is that an increase (or decrease) in calories consumed leads to an increase (or decrease) or energy expended until an equilibrium is reached. This paper from Nutrients, explains it that the way body weight settles is:
“determined by environmental and socioeconomic factors, such as diet and lifestyle, in interaction with genetic pre-disposition, or, to phrase this more generally, in interaction with the individual’s constitution. Precise regulation takes place without a fixed setpoint, rather body weight settles based on that resultant of a number of contributors”.
Similar to the set point model above, the settling point theory proposes that body weight settles at a range due to:
- Food intake
- Energy expenditure
This model takes into account the parameters that make up a person’s constitution (the genetic and epigenetic contributors) such as:
- Metabolic rate
- Body size
- Body composition
- Metabolic efficiency
- Propensity to physical activity
- Energy and nutrient availability
- Palatability of food
- Physical activity
- Living and working environment
Together, these contributors determine the settling point value.
The settling point models differs from the set point model in that the increase or decrease of body fat is not determined by a predetermined fat level, but rather the intake and use of the energy (calories). Thus, weight is maintained when the various metabolic feedback loops, which are “fine-tuned” by the relevant genes, settle into an equilibrium with the environment.
All these different contributors interact and together determine the point where body weight settles. This model accommodates many of the social and environmental characteristics of energy balance, but it doesn’t fully explain the biological and genetic aspects of body weight, as well as the gene-by-environment interactions. Which brings us to a third set point theory model.
The Dual Intervention Point Model
This model is hybrid of the set point and the settling point models. It combines the set point model involving active regulation based on body fat stores, with the settling point model of passive regulation operating in between them. There is not a single set point, but instead upper and lower boundaries where body weight regulation at a physiological level becomes dominant. There is also no predetermined target weight (as proposed by the set point model) nor interacting contributors to weight-energy intake and expernditure-as proposed by the settling point model.
The dual intervention model suggests these contributors can be regulated independently. As the above mentioned paper from Disease Models & Mechanisms explains it: “This aspect of the model is useful in that it allows for the inter-individual susceptibility to weight gain in a common environment, and is consistent with the results of studies showing a genetic contribution to the variance in BMI. However, the nature of the intervention points is unclear, and might be determined by a combination of genetic and environmental factors acting in concert”.
As we can see, although the fact that the body likes to stay at a particular weight range is evident, according to the evidence we can also notice that that weight isn’t as simple as calories in=calories out, but on a complex set of internal and external signals—a combination of environmental and biological factors. No set point model is perfect, but they do suggest that weight control is not as within our control as diet culture would have us believe.
How do you determine your body’s set point?
Although no tool is currently available to determine what your body’s set point is, you can have an idea by examining your own weight history, relationship to food and body. For example, if your weight has been relatively stable your adult life, if you haven’t dieted much, if you exercise regularly and comfortably, and if you are in good health, there’s a good chance you are where your body wants to be.
On the flip side, if you regularly restrict food yet stay at the same weight or gain weight, if you over exercise, eat only certain amount of foods, or stick to a particular eating regime to maintain a certain number on the scale, you are probably not at your body’s natural set point. Other clues that you may not be at your natural weight set point are:
- Stress or emotional eating on the regular
- Eating past fullness
- Ignoring hunger cues
- Using exercise to “burn off” or “earn” food
- Gaining weight quickly when you eat a bit more or exercise a bit less than you usually do
- Feeling guilty when eating certain foods
- Vowing to start “eating healthier” (ie, lower in calories) after eating “forbidden” or “bad” foods
- Feeling out of control around certain foods
Can you change your body’s set point?
So by now you may be wondering: can you change your body weight set point? Some believe in fasting to reset weight set point while others ask :”are toxins involved in set point theory?”
Although diet culture and the internet fitness “gurus” would have you believe that you can change your body’s set point, there is a lot of evidence, as this paper explains, to suggest that being able to change your set point dramatically may be difficult. As we saw above, most people who intentionally lose weight regain it back within a period of 1-5 years. What is more likely to happen is what is proposed by the Dual Intervention Point Model: we may be able to shift our weight within the upper and lower intervention boundaries, but less likely to be able to jump well below or above that for an extended period of time.
In other words, if your set point range is 130-145 pounds, you can “influence” where you fall in that range by eating more or less, or exercising more or less, but these efforts will be more likely to be thwarted if you try to get down to 110 pounds or up to 165 pounds.
And although chronic dieting may raise your set point, you may be able to bring it to the levels that are normal for you by eating normally and exercising regularly. It may take up to a year, more or less depending on how long the weight control behaviors have lasted, but it is possible.
Letting go of weight woes
As I mentioned in the beginning, we live in a culture where the thin ideal is worshipped and being in a larger body is considered to be the worst thing ever (which is completely false). Yet, learning to accept that your body weight is not where you’d like it to be (and “where you’d like it to be” is actually part of the programming on body acceptance you received in this toxic culture), can be downright scary. Especially when we’re constantly bombarded with impossible body ideals and diets that promise to get you there.
One way you can start letting go of trying to be at a certain weight is by exploring your desire to lose weight, as well as your motivations for wanting to do so. What makes you believe that being “x” weight will finally make you happy/accomplished/successful/loved? What does it mean for you that your set point is “x” amount? Dig deep and keep in mind how the diet mentality operates in order to see if your motivations are truly your own, or if they were conditioned by diet culture. In this case, journaling can help you learn more about your motives, where they came from, whether they really represent your truth and how can you really honor who you are.
In summary of the various set point theories discussed, we can see that it’s not easy to explain how body weight changes over time, or why exactly body weight likes to stay within a certain range. We can, however, see that genes and environmental influences do play a very important role, and just being aware of this can help us avoid the diet trap and learn to start embracing and celebrating our uniqueness.
It takes time and practice in order to unlearn those toxic cultural messages that we are programmed with in Western society. If you’re having trouble with body weight acceptance and/or your issues around dieting feel particularly challenging, consider seeking out a professional who can help you, guide you and give you the support you need.
And now I’d love to know your thoughts on the weight set point theory? What challenges do you think get in the way of letting go of having to be a certain weight? What tactics do you think could be helpful to learn to start accepting your body? Let me know below in the comments section.
Hi! I’m Melissa, Registered Dietitian and mother of two dragons. When I’m not talking nutrition you can find me rolling around the floor with my kids, sewing, crafting, cooking or missing the 90s (seriously, music just isn’t the same). Read More…