# A few case studies in weight loss

• For the last 7 years or so, I have weighed $x$ kg ($x$ is an embarrassingly large number + 10). Doing large amounts of cardio would cause my weight to decrease to $x-2$, but dropping such an unsustainable exercise regimen would cause it to jump right back to $x$. Eating an unhealthy amount of junk food would cause my weight to jump to $x+2$, but switching back to regular food without any additional restrictions would cause it to flip right back to $x$. It’s almost as if my $x$ is an equilibrium weight for me, and introducing massive changes in my routine would only temporarily change my weight to $x\pm 2$.
• I know an Instagram influencer who regularly posts “before” and “after” pictures as part of sharing her weight loss journey. The “before” photo shows her quite overweight and unhealthy, and the “after” photo shows her thin, slightly muscular, and really just brimming with health. We should start doing whatever she’s doing, right? Well…there are aspects of her weight loss that she keeps less than public on her social media. The “before” overweight her was just a temporary phase. She was, on average, not overweight, even before she started her grueling diet and exercise regimen. Moreover, even today when she eventually derails from her diet and exercise for even a week, she starts looking more or less like she did before she started trying to lose weight. It seems like even she has an “equilibrium” weight that she keeps switching back to as soon as she’s not able to maintain her strict diet and exercise routine.
• I know multiple people who managed to shed lots of pounds and body weight almost overnight by following the ketogenic diet. However, as soon as life hit and they had to get off the diet, they regained most of their body weight within a couple of weeks. The loss of fat was perhaps as dramatic as its gain.

What do I want to communicate with all of this? Perhaps one of the most influential things I have ever read is a series of posts on Slime Mold Time Mold, titled “Studies on Obesity”. The first post in the series is this. The author, a graduate student at a top university and funded by all sorts of prestigious organizations, concludes after years of study that our body regulates our body weight like a thermostat regulates the room temperature. Let’s probe this analogy deeper.

Let us assume that a thermostat is supposed to keep the room temperature constant at 25 degrees Celsius. If we suddenly open the windows to let in cold air from outside, the room temperature will drop. However, the thermostat will now work extra hard to push the room temperature back to 25 degrees. The heater will start blasting really hot air, and the room will only rarely get below 20 degrees. Moreover, when the door is closed, the room will soon return to 25 degrees. The same happens when you try to warm up the room.

Similarly, the body too has a body weight thermostat (in the lower part of the medulla oblongata) that works hard to maintain your equilibrium body weight. If you start starving yourself or eating loads of high-fat food, your thermostat will ensure that you don’t veer too far from your equilibrium weight. Moreover, as soon as you return to your regular routine, your weight will shift right back to your equilibrium weight.

But what about those people who we all know (primarily through the internet) who managed to lose more than a hundred pounds? Well, taking the analogy of the thermostat, they kept the room open to cold winds for way too long (they exercised hard for extended periods of time and ate very little carbs). Finally the temperature dropped to 0. However, should they return to their previous lifestyles, their body weights are likely to jump back to the original figure.

So what is perhaps the only way to lose weight without having to keep doing lots of exercise and eating only celery? We need to change our thermostat settings. We need to somehow tell our body thermostats to change the equilibrium weight. Then we would not need to work hard to maintain our desired body weights. The next generation of diet pills, that are in the process of getting FDA approval, aim to do precisely that.