Adolescent THC Exposure Alters Metabolism in Mice
A 2023 study in Cell Metabolism found that repeated exposure to THC during adolescence changed how mice gained weight and processed energy later in life. The findings point to lasting effects on fat tissue and metabolism—but they do not show that cannabis is a weight-loss treatment or that people who use cannabis will become leaner.
In the study, researchers gave male and female adolescent mice a daily intraperitoneal injection of 5 milligrams of THC per kilogram of body weight for two weeks. The treatment covered a period considered broadly comparable to adolescence in humans. THC-exposed mice gained less weight than control animals during the treatment period, although their body weight later returned to a typical range after exposure ended. More detailed metabolic testing was conducted primarily in male mice.
The researchers investigated several possible explanations for the reduced weight gain. In the male mice, the difference was not explained by lower food intake, impaired nutrient absorption, reduced physical activity, or changes in basic skeletal growth measurements. During and after treatment, the animals also showed changes in energy expenditure, fat use, body composition and the activity of brown and white adipose tissue—the tissues involved in storing energy and producing heat.
The most unusual findings were molecular. Fat tissue from THC-exposed mice showed increased production of proteins normally associated with muscle, while skeletal muscle displayed changes involving some of those same proteins. The cells looked normal under a microscope, but their gene activity and protein production had been altered. The researchers proposed that this abnormal protein expression could affect how fat tissue stores and releases nutrients, though the study did not establish exactly how the changes occur or what they mean for health.
Because the mice were examined into young adulthood, the results suggest that adolescent THC exposure may produce metabolic effects that persist after the drug has left the body. However, “persistent” does not mean that the same effects have been demonstrated in humans, nor does it establish that the changes are permanent. The study also did not directly test attention, learning or other mental processes. Any possible connection to those functions remains speculative.
The findings are biologically plausible because the endocannabinoid system operates throughout the body, including in adipose tissue, where it helps regulate energy storage, appetite and metabolism. A full report of the mouse study describes the changes as a disruption of energy balance and adipose-organ function following adolescent THC exposure.
Human research has reported an association between cannabis use and lower BMI in some groups, but those studies are observational and cannot establish that cannabis caused the difference. For example, one analysis of U.S. survey data found that daily users had modestly lower BMI than nonusers, while a 2017 Danish longitudinal study found no evidence that cannabis use during adolescence was associated with weight change from adolescence to midlife. Differences in diet, tobacco and alcohol use, physical activity, socioeconomic factors and other characteristics may help explain conflicting results.
That distinction matters. A lower average body weight among cannabis users does not mean THC safely promotes weight loss, and the mouse study offers no basis for using cannabis to manage body weight. In particular, adolescence is a period of continuing development. The Centers for Disease Control and Prevention’s information on cannabis and teens notes that regular cannabis use during adolescence may affect the developing brain and carries other health risks.
For now, the research supports further study of how THC affects metabolism during development—not the idea that cannabis is a diet aid. Maintaining a balanced diet, regular physical activity and appropriate medical care remains the evidence-based approach to managing weight.
