Have you ever noticed that your weight fluctuates all the time, yet you usually stick around the same weight? Well, this can be explained by set-point theory. So what is set-point theory? Set-point is the weight an individual usually hovers around and varies from person to person. This depends on their genetics, homeostatic factors, number of fat cells, hunger hormones, as well as your environment. It’s not uncommon to drift anywhere between +/- 5 lbs.This can happen due to a vacation, weekend holiday, or many other factors. Either way, our body has natural mechanisms in place to deal with this.
One mechanism being homeostasis, which is an unconscious process controlled by the hypothalamus in our brain stem. This mechanism keeps us alive and also controls your weight. Not only does homeostasis play a vital role in maintaining our body temperature, blood pressure, and blood glucose, but it may also play an aspect in our set point.
When our weight is over or below its set point, our body will naturally sense this and attempt to correct it, which means your body will want to keep you at the weight you are. This auto regulation would be considered homeostatic or your body’s equilibrium. Two hormones that come into play are ghrelin and leptin. Ghrelin is the fast-acting short-term hormone that is released by the stomach and compels us to eat. While leptin is a more long-term contributor to weight maintenance.
For example, leptin, the satiety hormone, fluctuates based on the size and number of fat cells in our body. Now, let’s say we just went on a vacation to Hawaii for 1 – week and gained 5 lbs from our set point by drinking Mai Tais. Because of leptin your body will auto regulate and bring you back to your set point, or your homeostasis weight. However, leptin works both ways. If you lose 5 lbs leptin will also bring you back up to your set point.
Now that we understand set point, is there a way we can change it? Certainly! By gradually losing weight over a few months (1-3 lbs per week) rather than 15 lbs in a week. By losing weight gradually you allow your body to adapt. If you lose weight too quickly it will shock your body and it will fight the weight loss even more. Once you reach your goal weight you must stay at this weight for at least 6 months. Your body will then auto-regulate and make new levels of hunger hormones. Now your goal weight becomes your new set point.
Written by: Ryan Ng, B.S Dietetic Intern,
San Francisco State University