This time of year tends to bring a surge in diet-related content, with crash diets, juice cleanses, and trendy fad diets promising quick weight loss. While exercising and enjoying a balanced diet is always the best approach, seeing long-term results is often easier said than done, and the hardest piece in the puzzle is keeping the weight off.

Rest assured, weight loss is something that many people struggle with. Current statistics show that 63.8% of adults aged 18 years and older are estimated to be overweight or obese.

If you’ve been researching the reasons why some of us are able to lose weight through dieting, but quickly put the pounds back on after, you might have come across something called the ‘weight set-point theory’. This simple scientific notion suggests that our DNA might have more to do with our weight loss efforts than we think.

Weight set point theory explained

Put simply, the weight set point theory suggests that our bodies have a genetically determined weight range to which they naturally gravitate and defend, making it challenging to sustain significant weight loss or gain outside of this range.

This theory is essential for understanding how our bodies manage weight and energy balance. Essentially, it suggests that our bodies work to maintain a stable weight by adjusting both our food intake and energy expenditure.

Imagine your body as a pair of twin scales, constantly striving for balance. If you consume more calories than you burn, your body adjusts by reducing appetite and increasing calorie burning. Conversely, if you’re in a calorie deficit, your body may increase hunger and become more efficient at using energy.

Does this idea of a ‘set point’ really hold up?

Let’s dive back into the question of whether this concept is truly valid. In my view, it absolutely is, and here’s why: Both experimental and clinical evidence tells us that when we adjust someone’s energy balance, their body responds accordingly. For instance, when we encourage weight loss by reducing food intake (and possibly increasing activity), research shows that the body’s metabolic rate decreases proportionally in response to the calorie deficit, especially in individuals who are overweight or obese.

This happens because various ‘thrifty mechanisms’ kick in, aiming to conserve energy by reducing processes like thermogenesis. Plus, appetite suppression during deficit and weight loss is tempered by decreases in hormones like leptin, as well as gut hormones such as PYY and GLP-1. These responses occur during the initial phase of weight loss, leading many to find that they don’t shed as much weight as expected — a phenomenon we’ve recently confirmed through mathematical modeling of real weight loss scenarios.

But it’s not just about losing weight. The set point theory also explains why gaining weight can be difficult for some individuals. Those who have been chronically underfed may have a suppressed metabolism and heightened sensitivity to appetite-suppressing hormones. So, when they try to eat more to gain weight, their bodies may resist, making the process challenging.

Can I change my set point or is it fixed?

Making gradual changes over time can eventually shift your set point, similar to getting used to a certain level of eating and activity. This is what happens with obesity – it develops gradually over time, so the body adjusts to being overweight.

So, compared to someone who’s lean, obese individuals already have higher metabolic rates and appetite suppressants because they’re used to eating more. When they cut calories, their bodies react more strongly because they’re starting from a higher point.

Similarly, someone who’s been consistently under-eating has a slower metabolism and is more sensitive to appetite suppressants due to low levels of certain hormones. So, when they eat more, their bodies react strongly, making it hard to rebuild weight.