Lean, also known as “Sizzurp” or “purple drank,” is a mixture of prescription-strength cough syrup, a soft drink, and sometimes hard candy. The cough syrup usually contains the antihistamine promethazine and the opioid codeine. Consumed in large volumes, this cocktail carries both pharmacological and nutritional effects. Whether this substance contributes to significant weight gain depends on the caloric intake from the sugary components and the metabolic changes induced by the active drug ingredients.
The Caloric Reality of Lean’s Ingredients
The primary driver of weight gain comes directly from the volume of simple carbohydrates ingested. A typical preparation involves mixing 4 to 8 fluid ounces (120 to 240 milliliters) of prescription cough syrup into a large soft drink, such as a 20-ounce bottle. Prescription cough syrups are thick liquids, relying heavily on corn syrup or sucrose to mask the bitter taste of the active ingredients. This high concentration of sugar makes the base liquid highly caloric.
Consuming 8 ounces of syrup means ingesting over 180 grams of sugar, translating to over 700 calories just from the syrup base alone. This is compounded by the accompanying soft drink; a standard 20-ounce bottle typically adds another 240 calories and 65 grams of sugar. The final mixture delivers nearly 1,000 calories and over 250 grams of sugar. These are considered “empty calories” because they lack fiber, protein, or other macro and micronutrients. This consumption pattern represents an immediate and unsustainable caloric surplus, drastically increasing the likelihood of weight accumulation.
How High-Sugar Intake Leads to Weight Gain
Rapid consumption of high sugar volumes creates a significant metabolic event. Simple sugars, like sucrose and corn syrup, are quickly broken down into glucose and absorbed rapidly into the bloodstream. This influx of blood sugar registers a high glycemic index, immediately signaling the pancreas to release a large amount of insulin.
Insulin clears glucose from the bloodstream, transporting it for immediate energy or storage as glycogen in the liver and muscles. When the body is flooded with glucose, the limited storage capacity for glycogen is rapidly saturated. Insulin then directs the remaining surplus glucose to be converted into fatty acids through de novo lipogenesis, which are packaged and stored in adipose tissue.
Chronic consumption of these sugary drinks keeps insulin levels consistently elevated, favoring fat storage over the utilization of existing fat reserves for energy. Furthermore, the liquid calories do not trigger the same satiety signals as solid foods containing fiber or protein. This lack of fullness means the user is less likely to reduce their food intake later in the day, contributing to a persistent caloric surplus and body fat accumulation.
Other Factors Contributing to Weight Changes
Beyond the simple caloric excess, the active drug components introduce several physiological and behavioral factors that promote weight gain. Promethazine is a first-generation antihistamine with sedative effects, while codeine is an opioid that induces drowsiness and reduced psychomotor function. The synergistic effect of these drugs depresses the central nervous system, leading to lethargy and a reduction in spontaneous physical activity.
This drug-induced sedation translates directly into a much lower daily energy expenditure, meaning fewer calories are burned throughout the day, even during routine activities. Since the basal metabolic rate remains relatively constant, a substantial reduction in non-exercise activity thermogenesis (NEAT) exacerbates the caloric surplus created by the sugary drink. The combination of high caloric input and reduced caloric output creates a highly efficient environment for accumulating body fat.
Chronic use of opioid medications like codeine can also interfere with the body’s endocrine system, potentially influencing body composition through hormonal imbalances. Opioids are associated with hypogonadism, a condition characterized by abnormally low levels of sex hormones, such as testosterone in men and estrogen in women. Low testosterone levels are known to disrupt metabolism, often leading to a decrease in lean muscle mass while simultaneously favoring the accumulation of fat mass.
The disruption of the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the stress hormone cortisol, is another metabolic consequence sometimes observed with chronic opioid use. Dysregulated cortisol levels can promote the storage of visceral fat, which is the type of fat stored deep within the abdominal cavity and is strongly linked to metabolic dysfunction. Furthermore, the lifestyle often associated with chronic substance use contributes to weight changes as the focus on consumption can lead to the neglect of exercise and healthy dietary planning, further solidifying the state of chronic caloric surplus.