Substance misuse and drug addiction can have a lot of harmful effects on your physical and mental health. The exact risks will vary depending on the drug involved and other factors, including the heaviness and duration of use. One potential impact is that some drugs may cause or contribute to fluctuations in your weight.

In some cases, you might gain weight – alcoholic drinks tend to be full of ‘empty’ calories, for example, and can lead to weight gain. Chronic drinking can also lead to weight loss, however, and a number of other drugs can also lead to unhealthy weight loss.


Effects of Drugs on the Body

So, why do drugs cause weight loss? The answer is it varies, depending on the type of drug.

Stimulant Drugs and Weight Loss

Stimulants such as cocaine, amphetamines and ecstasy can suppress your appetite, potentially leading to weight loss through reduced food consumption and increased activity (such as dancing), especially if these drugs are used regularly.

 There is also some evidence that stimulants like amphetamines can reduce body weight by altering metabolic rate and fat metabolism – the rate at which we expend energy and burn fat throughout the day. Stimulants used to treat ADHD may also have an impact, and it has been observed that children given medications like Ritalin can start to lose weight.

There is also an established link between cocaine and weight loss that may go beyond appetite suppression. One study suggested that cocaine addiction and chronic use of the drug caused profound metabolic changes, reducing the body’s ability to store fat.

Opioids and Weight Loss

Chronic users of illegal opioids such as heroin can experience swift and catastrophic weight loss. This tends to be an indirect consequence of using the drug, however. People using heroin will often have ‘chaotic’ lifestyles and may neglect many parts of their lives – including eating regularly and well.

There is some evidence, in fact, that opioids themselves can actually cause weight gain. There may be a number of reasons for this, including lowered rates of inactivity, changes in metabolism and even cravings for sugar.

Alcohol and Weight Loss

We’ve all heard of the so-called beer belly, and it is certainly the case that drinking can cause weight gain. This can be due to the extra calories in the alcoholic drinks themselves, as well as increased appetite and poor food choices made when intoxicated.

Chronic alcohol use and alcoholism may be associated with weight loss, however. As with heroin abuse, this may be down to a basic lack of self-care, with the chronic drinker neglecting to eat regularly or well. There may also be other serious issues, such as liver disease and cirrhosis, which can be caused by chronic alcohol consumption and can lead to loss of appetite and weight loss.


Health Risks of Drug-Induced Weight Loss

Weight loss from drugs can pose a risk to your physical and mental health. Losing weight, in general, can be a good thing, but when it stems from drug addiction and/or substance misuse, it is rarely done in a healthy or beneficial manner.

In many cases, users may be at risk of malnutrition, which the World Health Organization (WHO) defines as ‘deficiencies or excesses in nutrient intake, imbalance of essential nutrients or impaired nutrient utilisation’.  This can be caused by not eating enough – either through the appetite-suppressing effects of stimulants like cocaine or amphetamines, or the chaotic lifestyles and lack of self-care associated with heroin or alcohol dependency.

In other cases, the drug itself can affect our ability to get the nutrients we need out of food and drink. Opiates such as heroin can affect gastrointestinal motility or the way food progresses through the system. Alcohol, meanwhile, affects the absorption of nutrients in a number of different ways. It can irritate the gastrointestinal system and injure the lining of the small intestine, interfering with the body’s ability to absorb vital nutrients. Some vitamins, including thiamine (vitamin B1) and other B vitamins, are used to process alcohol instead of elsewhere in the system, and the diuretic properties of alcohol mean that you may ‘pee out’ other important nutrients.

Other impacts of a drug and weight loss problem can include a weakened immune system, cardiovascular problems and psychological issues. Up to 35% of people who were dependent on alcohol or other drugs have also had eating disorders, a rate 11 times greater than the general population. There can be a complex relationship between eating disorders and substance misuse, however, with both sides impacting the other to different degrees.


Dangers of Drug Use and Weight Loss

The Health Survey for England 2021 estimated that more than a quarter (25.9%) of adults in England are obese, with a further 37.9% being overweight but not technically obese. Clearly, most of us could do with shedding a few pounds, but this should always be done safely and slowly.

The weight loss drug Wegovy has recently been given the go-ahead for use in the UK but only under certain conditions. NICE recommends that it only be used for adults who have at least one weight-related comorbidity and a particularly high body mass index (BMI) and then only in a controlled weight loss programme that also includes safe calorie control and lifestyle advice.

The answer to the question, ‘Do drugs cause you to lose weight?’ is that they certainly can, but ‘self-medicating’ with drugs is never a good idea. As well as the risks of drug addiction and other physical and mental health issues, the weight loss associated with drug use can be very unhealthy.


Supporting Loved Ones with Drug Addiction

It can be difficult to know what to say to loved ones struggling with drug addiction and related weight loss issues. It can help to foster open, non-judgmental communication and encourage a healthy lifestyle, but professional help may also be required.

If you are worried about these issues in relation to yourself or a loved one, get in touch today to find out how we can help. Call us at 0800 880 7596 to chat directly with our friendly and understanding admissions team.

John Gillen - Author - Last updated: August 4, 2023

John is one UK’s leading professionals in the addiction recovery industry. Pioneering new treatment techniques such as NAD+ and ongoing research into new therapy techniques such as systematic laser therapy, John is committed to providing the very best treatment for people throughout the UK and Europe. During his extremely busy schedule, John likes to regularly update our blog section with the latest news and trends in the industry to keep visitors to our site as well informed as possible on everything related to addiction treatment.