A known fact about marijuana is that it causes munchies. Besides, doctors also prescribe the plant to improve appetite. That is why cannabis is often connected to obesity in later life. However, a new study shows that long-term cannabis use does not affect our weight.
A few years ago, a Canadian study demonstrated that marijuana use was associated with lower percentage fat mass, lower BMI, and lower fasting insulin levels. The researchers suggest that these findings may be the result of the plant's effect on tissue metabolism. In addition, they conclude that smoking cannabis may lead to increased energy expenditure. This means that cannabinoids stimulate physical activity and help us control our weight.
In general, they came to the conclusion that while the plant is used to stimulate appetite, long-term use is mostly associated with healthy eating practices.
The study showed us consistent results, but the cause behind them had to be further examined.
This year, a new Danish longitudinal study “Association Between Use of Cannabis in Adolescence and Weight Change into Midlife” was published. This work goes deeper into the issue of weight gain and appetite stimulation. The study took an impressive time to gather the necessary data. At first, the researchers surveyed adolescents between the ages of 15 and 19. And only 20 years later, they moved on to the next step and another examination. The study included such factors as self-reported height and weight, use of cigarettes and alcohol, use of cannabis, socioeconomic status, and physical activity levels.
The results show that people who consume cannabis are not more likely to gain weight than those who do not. Besides, the most impressive finding of this research was that the subjects who reported using cannabis in adolescence had the lowest increase in BMI, even after adjusting for alcohol intake and tobacco use.
Despite the promising results, there are some drawbacks that may have skewed them. Many participants dropped out during those 20 years. The fact might not be a problem if the percentage of obese people who withdrew was not higher than the number of those with a lower BMI who left the study. Few adolescents who started with a high BMI followed to the next step all those years later. Besides, the gathered data was self-reported, so it could be compromised as well. The researchers also mention that marijuana takers tend to under-report the regular amount of weed they use, which can mask the inverse relationship between cannabis intake and weight gain.
Overall, there have been a few studies on the issue, and only two of them are longitudinal. The general results are very inconsistent. Most but not all cross-sectional surveys claim that cannabis enthusiasts show lower BMI. The recent Danish study shows that there is no relation between cannabis consumption and weight gain. However, another longitudinal study published in 2013 showed an association between them.