The gravitostat

By Dr. John Ditraglia

Gravity is a mysterious force of nature that Newton and Einstein described.

There’s a thing called the set point. Somehow your brain has a detection system that keeps your weight stable even if your weight is too much. How does your brain sense how much you weigh? Well there might be another thing called a gravitostat.

Is leptin a gravitostat? We’ve learned a lot about leptin ever since it’s discovery in 1995 when it was initially heralded as the long awaited answer to curing obesity. Leptin is a hormone made mostly by fat cells that regulates fat stores in the body. Leptin talks to receptors in the brain and alas was not the holy grail of obesity understanding and cure.

Recently some Swedish scientists who are studying bone metabolism have come up with this gravitostat idea.(1) They did some projects on mice with different levels of inherent body weight (lean, overweight, and obese). They added weight to these variously fat mice with implanted casules loaded with various amounts of lead weights into their bellies. They found that overall weight regulates fat mass in obese mice but not lean mice, whereas leptin regulates fat mass only in lean mice with normally low levels of leptin in their blood. They proposed that some kind of gravitostat primarily protects against obesity, whereas low levels of leptin protect against undernutrition.

The other ways of studying this gravitostat would be to study people subjected to prolonged bed rest and astronauts who hang out at the international space station for awhile. We probably should know more about the hazards of bed rest but we have learned so far that the biggest effects of weightless in space are about bone and muscle wasting and fluid shifts such that these astronauts lose a lot of weight and are inclined to eat and drink less. The effects on fat metabolism and fat mass in both of these scenarios are less well studied.

As a wise man once said, “it’s just a thing.”

But hey, that’s easy enough to try. Just strap weights to your neck and hips and ankles and see what happens.

1. Ohlsson C. et al. The Gravitostat Regulates Fat Mass in Obese Male Mice While Leptin Regulates Fat Mass in Lean Male Mice. Endocrinology. 2018 Jul 1;159(7):2676-2682. doi: 10.1210/en.2018-00307.

By Dr. John Ditraglia