How Cocaine Makes Users Skinny

A new study examines the weird ways cocaine changes people's metabolisms.


U.S. Drug Enforcement Administration

Cocaine has long had a reputation for keeping users slim—check out this 1990 article from the Los Angeles Times—and there's some science to back that up, too. Now, a new study of cocaine-addicted men examines how, exactly, cocaine makes users thinner.

Cocaine can fundamentally alter the body's metabolism, the study found. Even though addicts eat more and have altered protein levels that should make them gain weight, they're actually likely to have less body fat than non-addicts.

Knowing this could help doctors manage the weights of those who stop using cocaine, the research team, four neuroscientists from the University of Cambridge in the U.K., wrote a paper they published in the journal Appetite. Many of those who quit cocaine gain a lot of weight and reducing that effect could keep people happier with abstinence and more likely to stay on the wagon.

Cocaine addicts reported eating more calories, fat and carbohydrates. Yet the addicts actually had less body fat than non-addicts.

The research team studied 65 men from around Cambridge. Thirty-five of them were active, addicted cocaine users. On average, they had used cocaine for 15 years in either powdered or freebase form. The rest of the men were matched in age to the addicts, but they had never used cocaine and didn't have any history of substance abuse. The majority of the cocaine users, on the other hand, were also dependent on other substances such as opiates, alcohol and cannabis. Ninety-one percent of the cocaine addicts were dependent on nicotine.

Compared to men who weren't addicted to anything, the cocaine addicts reported eating more calories, fat and carbohydrates. Yet their body mass indices—a measure of people's weights compared to their heights—were the same as non-addicted peers of the same age. The addicts actually had less body fat than non-addicts, while both groups had the same amount of lean body mass. That result was especially striking because tobacco smokers usually have more body fat than non-smokers of the same height and weight, yet cocaine seems to overcome that: Remember, 91 percent of the cocaine users in this study were addicted to tobacco, too.

Cocaine addicts had higher levels of leptin, a protein associated with weight gain and appetite control, than non-addicts. The difference wasn't statistically significant, but it suggests something different is going on in addicts' metabolisms, the Cambridge researchers wrote. Cocaine may interfere with people's ability to store fat, which would explain why addicts are leaner, but also want to eat more fatty foods.