For many, the idea of cannabis use leading to weight loss seems paradoxical. The stereotype of the "stoner" indulging in insatiable munchies is deeply ingrained in popular culture. However, emerging research suggests a more nuanced relationship between cannabis and weight management, challenging conventional wisdom. This article explores the scientific evidence surrounding cannabis use and its potential impact on weight, delving into the roles of specific cannabinoids, the endocannabinoid system, and various lifestyle factors.
The Endocannabinoid System: A Key Player
A number of important biological systems, including metabolism, depend on our endocannabinoid system. The endocannabinoid system (ECS) is a complex network of receptors, enzymes, and endocannabinoids (cannabinoids produced naturally by the body) that plays a crucial role in regulating various physiological processes, including appetite, metabolism, energy homeostasis, and immune function. The two primary cannabinoid receptors are CB1 and CB2. CB1 receptors are mainly found in the brain and central nervous system, while CB2 receptors are predominantly located in immune cells.
Maintaining proper endocannabinoid system tone for optimal metabolic functioning requires a nice balance of omega-6 (linoleum acid, LA) and omega-3 (α-linolenic acid, ALA) fatty acids. To keep our body burning and storing calories the way it should, we need a good omega-6/omega-3 ratio. Diving a little bit deeper into the science: Omega-6 fatty acids are precursors to two very important endocannabinoids known as AEA and 2-AG. Both cannabinoids act via CB1 and CB2 receptors. CB1 receptors play a huge role in energy homeostasis, including appetite and metabolism.
THC: A Paradoxical Effect
Δ9-tegrahydrocannabinol (THC) is the most well-known psychoactive compound in cannabis. It primarily interacts with CB1 receptors, leading to increased appetite and a heightened sensitivity to the hedonic properties of highly palatable food. This phenomenon is commonly referred to as "the munchies." According to scientists, stimulating CB1 receptors with THC results in an up-regulation of appetite. In fact, almost every study cited above highlights increased caloric intake among marijuana users. The same study also found that heavy users (subjects who reported using marijuana 11 or more times a month) consumed 582 more calories a day than non-users.
However, despite this appetite-stimulating effect, studies have shown that individuals who regularly consume cannabis tend to have lower body weight and a reduced risk of diabetes compared to non-users. This counterintuitive finding suggests that THC may have other metabolic effects that counteract the increased calorie intake.
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One possible explanation for this paradox lies in the long-term effects of THC on CB1 receptors. Pharmacodynamic research suggests that chronic THC use leads to downregulation and desensitization of CB1 receptors, which helps to explain why appetite stimulation is suppressed in chronic users. In recently abstinent users, reduced appetite and increased metabolic rates may occur because CB1 receptors remain down-regulated for several weeks following chronic cannabis consumption. However, they will no longer experience short-term stimulation of appetite (the “munchies”), energy intake and storage, and reduced metabolic rates during each episode of acute cannabis consumption.
Furthermore, a study from the University of California, Irvine, found that adolescent exposure to low-dose THC disrupts energy balance and fat storage processes in adulthood, leading to a leaner body and reduced risk of obesity and diabetes. Researchers gave low daily doses of THC or its vehicle to adolescent mice. They then stopped the treatment and, after the animals had reached adulthood, carried out a thorough assessment of the animals’ metabolism. Mice that had been treated as adolescents with THC, but were now drug-free, had reduced fat mass and increased lean mass, were partially resistant to obesity and hyperglycemia, had higher-than-normal body temperature, and were unable to mobilize fuel from fat stores. The researchers concluded that the effort required to make these ‘alien’ proteins interferes with the healthy functioning of fat cells and thus with their ability to store and release stored nutrients.
It's important to note that the subjective experience of cannabis appears to be dependent on the route of administration. For example, cannabis can be inhaled via smoking or vaping; ingested in the form of various foods/“edibles,” drinks, pills, lozenges, and tinctures; and topically applied in lotions or balms [14]. Inhaled routes of THC administration tend to lead to a rapid onset but shorter duration of increased appetite, whereas ingested routes lead to delayed and stronger increases in appetite that may last for hours.
THCV: A Potential Appetite Suppressant
THCV, a compound found in cannabis, differs from THC in its effects on appetite and metabolism. Unlike THC, which is known to stimulate appetite, THCV has been observed to decrease appetite and increase energy metabolism in rodent models. THCV primarily works by antagonizing the CB1 receptor; this compound can, therefore, have anorectic effects, inhibiting appetite, controlling food, and consequently decreasing body weight.101 However, at high dosages, THCV can demonstrate CB1 agonism and partial CB2 agonism.
THCV is known to act as a CB1 antagonist and a CB2 partial agonist. As an antagonist, THCV blocks the action of cannabinoids at the CB1 receptor, especially in the central nervous system. This action is crucial because CB1 receptors are widely implicated in appetite regulation and feeding behavior. Moreover, in lower doses, THCV appears to act as a CB1 antagonist, but in higher doses, it may start to activate CB1 receptors, albeit less intensely than THC.
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Research suggests that THCV may also influence metabolism. By interacting with the ECS, particularly through the CB2 receptors, THCV might help in regulating blood sugar levels and reducing insulin resistance.
CBD: Modulating Appetite and Fat Browning
Cannabidiol (CBD) appears to be associated with decreased appetite. According to research, cannabidiol-the main non-intoxicating cannabinoid found in marijuana and hemp plants-appears to modulate appetite in a few interesting ways. CBD acts on appetite-regulating cannabinoid receptors. Studies show that CBD interacts with CB1 and CB2 receptors in the brain and lymphoid tissue. Some of these receptors are thought to have a relationship with metabolism and appetite.
Moreover, rats that were injected with CBD at doses of 2.5 and 5 mg per kg of body weight displayed significant reductions in body weight, with more pronounced effects at the higher dose. CBD may increase or decrease appetite. In some animals and people, CBD may reduce food intake. This was the case in a rat study, where cannabidiol reduced appetite and other cannabinoids (cannabigerol and cannabinol) did not.
An intriguing aspect of weight loss research is the role of CBD oil in promoting the browning of fat cells. This process is essential for generating heat by burning calories, aiding in weight loss. CBD, a major cannabinoid found in cannabis, may contribute to the transformation of white fat into brown fat, which is more metabolically active and burns more calories.
Cannabis Use Disorder and Eating Disorders
Cannabis use disorder (CUD) is defined as a problematic pattern of cannabis use with clinically significant distress or impairment. Globally, approximately 10% of those who use cannabis meet criteria for CUD. Multiple studies have reported on cannabis use among individuals with eating disorders (EDs), particularly binge eating disorder (BED). In a systematic review and meta-analysis, CUD was one of the most common co-morbid diagnoses in individuals meeting criteria for an ED including AN, BN, BED, and eating disorder not otherwise specified (EDNOS). Those with binging and purging behaviors were more likely to evidence substance use disorders including CUD, which the authors postulated was due to this population having greater difficulty with emotion regulation and impulse control.
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Lifestyle Factors and Study Limitations
The impact of diet on the endocannabinoid system is predicted to vary as different populations consume different proportions of green vegetables, industrially produced animals, oceanic fishes, and processed foods.
It is important to acknowledge the limitations of current research on cannabis and weight loss. Many studies are observational, which means they cannot establish a causal relationship between cannabis use and weight. Additionally, studies often do not differentiate between cannabinoid profiles, routes of administration, or whether cannabis use is problematic.
Potential Implications for Medical Marijuana Patients
Medical marijuana patients who consume cannabis for chronic pain may find that cannabis products relieve symptoms, allowing them to exercise more.
For many patients, cannabis may be a better option for weight loss than surgery or pharmaceuticals. BMI is reduced in cannabis users and, if the present theory is true, should decrease even more when users stop using cannabis because CB1 receptors remain down-regulated for several weeks following chronic cannabis consumption.