A research team at the University of Gothenburg in Sweden recently published a study in The Lancet that really grabbed our attention. It discusses a previously undetected metabolic mechanism that helps to regulate body weight.
The mechanism is called the gravitostat. It is a “loading-dependent homeostatic mechanism that regulates body weight and fat mass”. Whew. That’s a mouthful, so let’s break it down:
- Homeostatic mechanisms: these are internal biological processes that work to maintain your organism in balance. An example of this is the internal process that keeps your body temperature steady when it gets hot or cold outside. Go deeper.
- The gravitostat is thought to be a homeostatic mechanism that helps to do the same thing for weight and fat mass. The hypothesis is that when your organism detects an increase in body weight, it tries to compensate by losing fat mass.
- This phenomenon was first observed in mice by this same team of researchers. They showed that using weight capsules to increase the load that mice carried reversibly decreased body weight and fat mass
- In this new study they set out to prove that the concept also applies in humans.
To test the hypothesis, they asked two groups of people (average age ~50 years old) to wear a weighted vest for 8 hours a day, over three weeks. One group used a vest weighing 11% of their body weight. The other group wore a vest equivalent to 1% of their weight.
The primary endpoint was the percent of change in body weight in the “high load” group compared with the “low load” group (as measured from the baseline).
The secondary endpoints included the percent of change in fat mass, fat-free mass, as well as other markers (again, as measured from the baseline).
The main finding was that the “high load” treatment indeed reduced body weight compared to the “low load” treatment. But more importantly, the weight reduction was concentrated in the loss of fat mass. Fat-free mass was unaffected.
- the body weight loss (relative change after 3 weeks) was statistically significant in the high load group but not in the low load group (−1.68%, vs −0.31%).
Analysis of the absolute change in fat mass demonstrated that the “high load” treatment reduced fat mass by 1.73 kg, while no statistically significant effect was observed by the “low load” treatment
Why is this relevant?
This effect of increased weight loading on body weight seems to be significant and robust when comparing with the variable—and often small—effects described in other controlled studies on exercise and lifestyle changes of a similar duration. Simply put, weight loading seems to be one of the most effective types of exercise, and certainly in the short term.
Based on these results, the researchers conclude:
“We propose that the decrease in...body weight is acompensatory effect to ...restore total...weight [to what it was before]...weight loading. Thus, the present findings would reflect a loading-dependent homeostatic regulation of body weight; the gravitostat.”
Try it for yourself
What we loved about this study is that it is very easy to try this at home. Simply get a backpack and put some heavy books or weight plates in it. (You can use the study’s 11% of body weight measure as a guide). Try it for a few hours a day over a month (the study did 8 hours a day for 3 weeks), and see the results by measuring your body fat composition. Let us know what you learn!
We did recently notice this company that promotes “rucking,” and it basically replicates the load-bearing approach used in the study we mentioned above. It is pitched astheexercise for people who dislike running. We wonder if they knew about the gravitostat...