TV doctors are known for issuing some interesting advice, but Dr. Oz’s latest has earned him quite a bit of ridicule. Dr. Oz tweeted that astrological signs “may reveal a great deal about [a person’s] health.” He included a link to a slideshow that claimed that Aries were more likely to suffer from migraines and Leos were more prone to upper back pain. Twitter, unsurprisingly, raked Dr. Oz over the coals for the tweet.

Astrology has become increasingly popular in recent years, but there is no clear link between a person’s physical health and the position of “their” stars. Health issues stem from a variety of causes including genetics, diet, environment, a person’s level of activity and their job. An office worker, for instance, is much more likely to deal with carpal tunnel syndrome after typing all day every day for years, and a construction worker is more likely to be at risk for throwing out their back if they lift heavy materials often. People who work with chemicals are more prone to respiratory infections while those who work outside have a greater risk of being sunburned and developing skin cancer. None of this, however, is dependent on the stars.

The one way that astrology could affect a person’s health would be through a variant of the placebo effect. The placebo effect is, essentially, when a person tricks themselves into believing that a useless medication is actually managing their symptoms. It is the ultimate case of mind over matter and plays a valuable role in medical research. When new drugs are tested using a placebo group, one group of volunteers is often given a placebo pill but told they have been given the actual medication. The placebo pill does absolutely nothing but mimics the appearance and taste of the actual medication. If the placebo group is “cured,” then there is the possibility that any effects of the actual drug are purely mental as well. If the placebo group shows no change, but the group with the actual medication recovers, then any change can be attributed to the chemical make-up of the drug. Astrology could potentially produce a similar effect. A person who is supposed to have a good day, might end up having a good day regardless of their actual condition. Mind over matter. The reverse, however, could also take place. Someone who is completely healthy might convince themselves that they have a headache because they are “supposed to” based on their horoscope.

Essentially, astrology has no real effect on a person’s health. They may think that it does and so it may have psychosomatic effects. When it comes down to it, however, those distant planets are not responsible for whether or not a person will develop a headache during their morning commute. That blame rests squarely on the shouting couple sitting across the train.