The Scoop on Body Weight Regulation and Metabolism: Weight & Health Series
Set-Point Theory suggests that our bodies have a natural weight range where they function optimally. This concept is crucial in understanding how factors like genetics, diet history, hormonal changes, and aging influence our body weight. As dietitians, we delve into how this theory impacts our approach to nutrition and health.
Your body will adapt to maintain that weight without much resistance, even when subtle change occurs. Many factors, such as genetics, dieting history, hormonal changes, and aging, can affect your set-point range. This topic tends to bring up a lot of feelings, fears, and opinions as it can be challenging to accept amidst our diet- and weight-centric culture. Set-point theory explains why weight loss often cannot be sustained over a long period of time. Set-point theory hypothesizes that your body fights against weight change by putting into place compensatory mechanisms.
Essentially, your body will adjust to periods of more food and less food to keep your body weight stable.
One of the ways your body adapts is by shifting hormones. For example, in response to food deprivation, we see an increase in cortisol levels (the stress hormone), a decrease in levels of leptin (the hormone that tells your body it's full), and an increase in ghrelin levels (the hunger hormone). This causes those in a deprived state to feel hungrier, and the hunger will remain even after eating a meal.
Along with these hormonal changes, there is an overall reduction in energy expenditure. This is because your body's metabolism slows down in an effort to survive. Your body registers a famine, leading to an override of a few of its "non-essential" mechanisms. One of the mechanisms altered in restriction includes thermal regulation. Those in a deprived state might notice that they are consistently cold when others around them are not or have cold hands and feet (this is your body conserving and pulling heat to warm your organs because that is more important than the extremities). Those in a deprived state might also notice that their digestion is off, tending to feel more bloated or constipated than usual.
Another way that the body responds to starvation and tries to keep you motivated for food is by increasing the reward value of food.4 It does this by changing various cognitive and attentional functions, which cause you to become hyper-focused or obsessed with food. An example of this process is outlined in the Minnesota Starvation Project conducted in 1944 on 36 men who were put on a restrictive diet of 1,400-1,600 calories/day (*Note: I find this interesting; this is not typically the calorie range that you may perceive as starving). While extremely unethical, this study gave us much insight into what happens during starvation.
As the men lost weight, besides the physical side effects of hunger (which were profound), they also became obsessed with food. Men began reading cookbooks, staying up late to look through recipes, and some even considered changing career paths to one related to food. The obsessions continued for months and some years after being refed. Studies confirm this effect by assessing different attentional focus tests, such as eye tracking methods, the attentional blink paradigm, or dot-probe tasks. The studies find that people's attention is biased toward food stimuli when calorie-deprived. Brain imaging studies also find increased brain activity in areas that control attention in calorie-deprived individuals when shown images of palatable foods. Studies have also found that smell functioning and palatability of foods increase when calorie-deprived.
In food restriction, uncertainty about food supply triggers an adaptive response to gain weight, similar to what our ancestors would have experienced during times of variable abundance and scarcity.
To summarize, these are all ways our body responds to a restricted state.
Hormones shift: An increase in cortisol levels (the stress hormone), a decrease in levels of leptin (the hormone that tells your body it's full), and an increase in levels of ghrelin (the hunger hormone) occur.
Thermal regulation: Feeling constantly cold when others around them are not or have cold hands and feet because your body is conserving and pulling heat to warm your organs.
Digestion: Those in a deprived state might notice their digestion is off. They feel bloated often or may experience constipation.
Metabolism: Weight loss produces metabolic shifts that favor lipid storage.
Neurological changes: The attention centers of your brain shift towards food, leading to an obsession or preoccupation with food. The brain's reward center sends a more substantial response when we eat. Smell functioning and palatability increase.
Finding Your Set-Point Weight
There is no one equation, chart, or test to determine where your natural set-point is. Your unique genetic blueprint determines this, which is why we humans could all eat the same and still have body diversity. Collectively, when we are at our set-point (excluding that we do not have a chronic illness or underlying medical issues, and our hormones are balanced), our labs are stable, our hair and nails are strong, our hunger and fullness cues are present, and it is effortless to maintain our weight. Effortless meaning we don’t count calories, restrict foods in any way, try the new diet fad, exercise to “burn off” what we’ve eaten, or constantly overthink food choices.
It is essential to point out that being at a healthy weight for you doesn’t necessarily mean “healthy” for others. One study showed that 38% of patients who were restricting calories lost their periods while still at a “normal BMI,” as many exhibited symptoms of starvation without being clinically underweight.
We can discover our true set-point by letting go of the sense of control with food and our body and instead trusting that our body will know where to land. This process requires time, patience, and a lot of self-compassion. Working with a HAES and intuitive eating dietitian can support you through this process.
Discovering your body's set-point requires letting go of the rigid control over food and trusting your body's innate wisdom. This journey demands patience, self-compassion, and the guidance of a knowledgeable dietitian. If you're seeking to understand your body's natural weight regulation and develop a healthier relationship with food, our team at CV Wellbeing is here to support you. Contact us for personalized and HAES-aligned nutrition counseling.