Tirzepatide, a drug to treat obesity

A study led by Yale University (USA) and published in the New England Journal of Medicine (NEJM) evaluated the drug tirzepatide to treat obesity. The phase 3 study was carried out in 9 different countries and included 2,539 adults who received a subcutaneous dose of tirzepatide of 5, 10 or 15 mg once a week for a year and a half. Study participants experienced weight reductions of 19.5% and 20.9% with the highest doses of the drug, while reporting mild, transient side effects, including nausea and diarrhoea.

Obesity is one of the most prevalent chronic diseases affecting biological, psychological and social aspects of a person's life. Over 650 million adults worldwide suffer from it. Excess adiposity and its many complications, including cardiovascular diseases, type 2 diabetes and cancer, are the main factors of global morbidity and mortality and have a negative impact on health systems.

"Obesity is a very complex disease. The body's adaptation mechanisms to changes in lifestyle contribute to not obtaining the expected results, because the disease itself prevents it,” explains Lilliam Flores, endocrinologist at the Hospital Clínic.

The USA and European regulatory agencies (FDA and EMA) had already approved tirzepatide to treat diabetes; however, the study published in the NEJM showed its efficacy in treating obesity. The drug consists of two peptides that, when combined, are more effective in reducing weight: one reduces the sensation of hunger while the other regulates the energy balance and the accumulation of fat in the body.

This drug has been shown to reduce weight by 21% in people with obesity, which is equivalent to a person weighing 100 kg losing about 21 kg. The study results show this drug can be an alternative to bariatric surgery. Also, it does not have to be a chronic treatment, but can be administered until weight is stabilised. This drug will not yet be covered by the public health system in Spain because obesity is not considered a chronic disease. However, the state does cover bariatric surgery, which is used when other treatments don't work.

Most study participants had a Body Mass Index (BMI) of 30 kg/m2 or higher. The BMI is calculated by dividing the person's weight (in kilograms) by the square of the height (in metres). The main weight classifications in adults are: low (BMI < 18.5), normal (BMI 18.5-24.9), overweight (25.0-29.9) and obese (≥ 30). This study included adults with at least one complication related to obesity, such as hypertension, dyslipidaemia (alterations in the amount of lipids in the blood), obstructive sleep apnoea, some cardiovascular diseases and having followed more than one weight-loss diet without satisfactory results.

The treatment of obesity has always had an approach based on changes in lifestyle, applied to diet and physical exercise. "Obesity is caused by an energy imbalance, with more calories being consumed than are burned. However, this disease is much more complex than this simple calculation, with multiple factors being involved in its appearance and persistence," explains Alba Andreu, a nutritionist at the Hospital Clinic.

Study participants received regular lifestyle counselling sessions from a qualified dietician or health professional to help them adopt healthy, balanced eating habits with a 500-calorie deficit per day, and at least 150 minutes of physical activity per week.

Information documented by: Dr. Lilliam Flores, endocrinologist from Endocrinology and Nutrition Service at Hospital Clínic de Barcelona and member of Translational Research group in Diabetes, Lipids and Obesity at IDIBAPS