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How Substance Use Affects Your Appetite

by Kayla Risteen - RD, CSG, LDN

September 20, 2022
A woman loses her appetite at lunch

4 Substances That Impact Appetite

Among the many side effects of substance use is the impact it has on a person’s appetite. Whether they use drugs or alcohol, prolonged substance use can prevent a person from feeling hungry and lead to malnutrition and unhealthy weight loss. On the other hand, a person under the influence of a particular substance might also overeat, which is a risk factor associated with choosing unhealthy foods that can lead to weight gain, obesity or other chronic diseases.

It’s important to understand how substance use impacts the body, including appetite. In this blog post, we examine the effects of four substances: stimulants, opioids, alcohol and marijuana.  

1. The Impact Stimulants Have on Eating

Central Nervous System (CNS) stimulants, such as cocaine or methamphetamines, are known to decrease a person’s appetite. But why does this happen? Stimulant use suppresses the amount of ghrelin – a hormone responsible for telling the brain when it’s time to eat and when you’re full – that is produced in the body.

Ghrelin, aka the “Hunger Hormone”

Ghrelin is a hormone made in the stomach, and also in small quantities in the brain. Under normal circumstances, your body produces higher levels of ghrelin when you haven’t had food for a while. The ghrelin sends signals to your brain that your stomach is empty, you’re hungry and you should eat something.

Stimulants can suppress the secretion of ghrelin, causing someone to feel less hungry than they really are.  It’s common for someone using stimulants to skip meals, or even go days without eating when they’re on a “bender.” As a result, repeated stimulant use could cause unhealthy weight loss and nutrient deficiency. 

There are instances, however, when a person who uses stimulant drugs might gain weight. When the effects of stimulants wear off, their body starts producing ghrelin again, and their appetite returns. This could cause them to overeat when they’re not using, which is a sign of physical dependence for people abusing prescription stimulants like Adderall or Ritalin, popular ADHD medications.

2. Opioids vs Appetite

While opioids don’t directly suppress appetite the same way stimulants do, many people experience a decreased appetite due to gastrointestinal (GI) issues often caused by the side effects of opioid use.

How GI Symptoms Decrease Appetite

Common GI symptoms include:

  • Nausea
  • Vomiting
  • Constipation

Obviously, when someone is nauseous and/or vomiting, they usually don’t want to eat anything. Constipation, a common side effect experienced by nearly 80% of opioid users, also plays a factor in decreased appetite. It occurs as opioids delay the emptying of the stomach and muscle movement as food travels along the GI tract (a process known as peristalsis). Fluid is unable to be absorbed into the intestines during this phase of digestion, which leads to the hardening of stool and difficulty going to the bathroom. Therefore, when someone is feeling “backed up,” full or constipated, their appetite tends to diminish.

Two women overeat a box a pizza while a man has no appetite for his salad

Using marijuana can cause people to overeat like the two women on the left, while using stimulants (cocaine, Adderall, etc.) can cause people to lose their appetite like the man on the right.

3. Alcohol use and Eating

When a person initially starts drinking alcohol, they might actually feel hungrier than when they’re sober. Research estimates that this happens due to the stimulation of nerve cells in the brain’s hypothalamus, the part of the brain that helps control appetite. Additionally, calories from alcohol don’t provide quality nutrients the same way that macronutrients (carbohydrates, fat, protein, etc.) do. 

Drinking “empty” calories from alcohol won’t make you feel full. Instead, casual or excessive drinking can cause you to crave high-calorie items like fast food or pizza.

Dangers of Long-term Alcohol use

Long-term alcohol use can cause a decreased appetite over time. Heavy drinkers may even experience unintended weight loss due to the damage being done to their organs. The damage usually starts in the GI tract, as alcohol irritates and causes inflammation in two digestive organs: the stomach lining and the small intestine.

Any damage to these two digestive organs can cause someone to have trouble absorbing key nutrients from food and drinks, leading to vitamin and mineral deficiencies down the road. As alcohol is digested, it filters through the liver. When a person excessively drinks alcohol, their liver must work harder to break down the alcohol, and thus doesn’t have a chance to clear the toxins and recover before repeating the process. This excessive alcohol use can lead to liver disease. When the liver isn’t functioning properly, it can also cause toxic substances to build up in the pancreas, which can lead to inflammation of the pancreas, known as pancreatitis. Liver disease and pancreatitis are often accompanied by the loss of appetite and many other painful symptoms, including:

  • Nausea/vomiting
  • Diarrhea
  • Abdominal pain and swelling
  • Indigestion

4. How Marijuana Affects Eating

When someone smokes marijuana – or ingests it via an edible (brownie, cookie, etc.) – they often experience an increased appetite, also known as the “munchies.” Experts believe there to be two possible reasons for this: 

1. THC increases appetite whether or not someone is hungry

The tetrahydrocannabinol (THC) chemical in marijuana needs to bind to cannabinoid receptors to produce a “high.” These receptors are located in the body’s CNS, which includes the parts of the brain that promote appetite and make a person hungry.

2. THC increases ghrelin (hunger hormone) levels

THC has also been shown to stimulate the release of ghrelin (that hunger hormone we talked about earlier), causing levels to increase. Marijuana use can cause increased levels of ghrelin, which is followed by signals to the brain that it’s time to eat. The increased appetite for people using marijuana often comes with an increased intake of food. People under the influence of marijuana typically reach for high-calorie fats, salts, and sugar, because they’re perceived as more rewarding in the pleasure centers of the brain.

What it all Means?

Whether a substance increases or decreases your appetite, you should be aware of the potential risks associated with substance use. When appetite is suppressed, it causes food intake to decline. Any prolonged lack of food can lead to malnutrition, which often causes dizziness, fatigue, unintended weight loss and muscle weakness. Severe cases of malnutrition can lead to organ failure and even death.

When appetite is increased, we tend to eat more. Eating more than our body needs for an extended period of time can lead to unexpected weight gain, obesity and other comorbidities.

How to get Help for Substance Use Disorder

If you or someone you know is struggling with drugs or alcohol, Landmark Recovery can help! Call a recovery specialist today at 888-448-0302 to get more information about what to expect from SUD treatment, or visit our locations page to find a rehab center near you.

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About the Author

Kayla Risteen - RD, CSG, LDN

Kayla Risteen - RD, CSG, LDN

Kayla Risteen is the Director of Dietary Services at Landmark Recovery. She graduated with a Bachelor’s of Science in dietetics from the University of Kentucky and has been a practicing Registered Dietitian for eight years. She has a passion for nutrition education and helping those in recovery reach their fullest potential through proper nourishment. Outside of work, Kayla enjoys spending time with her husband and their Bernese Mountain Dog, Gus. She loves to run races of any distance and hopes to run an ultramarathon one day.