How and when should obesity be treated with drugs?

Last June, the media announced the existence of a drug capable of producing a loss of more than 20% of weight in obese patients. Called tirzepatide, it has aroused public interest in this type of compound.

But the use of drugs against overweight is not new. Although the basis of any treatment is a low-calorie diet combined with physical exercise, for decades there have also been molecules that help reduce excess kilos.

Three Proven Effective Compounds

Currently, there are three drugs available in Spain that have proven their effectiveness:

– Orlistat: It is a molecule administered orally that reduces the intestinal absorption of fat from food. You can reduce up to 4% of the starting weight.

– Naltrexone: This opioid antagonist, used in the treatment of alcoholism and to prevent relapse of opiate use, is combined with bupropion, an antidepressant used against smoking. The joint action of both reduces appetite and achieves losses of 5% of body weight on average.

– Liraglutide: Daily subcutaneous administration, mimics the effect of GLP-1 (Glucagon-Like Peptide-1). This intestinal peptide, which is synthesized in response to the presence of food in the digestive tract, stimulates insulin secretion by the pancreas after meals. Another peptide participates in the process, GIP (Glucose-dependent Insulinotropic-Polipeptide). GLP-1 and GIP also generate feelings of satiety by acting on a region of the brain called the hypothalamus. Patients who are prescribed lose up to 7% weight.

soon in pharmacies

In addition, in the coming months, the incorporation of other drugs from this last group, called incretin mimetics-incretins, can be expected. One example is semaglutide, which is administered subcutaneously weekly and has shown weight reductions of up to 14%.

As for tirzepatide, the molecule that has recently drawn attention, it has a dual effect: it acts simultaneously on the brain receptors for the incretins GLP-1 and GIP, regulating the sensation of appetite. It is expected that it will also be available in Spain in the medium term, as well as other molecules currently under development.

Side effects

It must be considered that drugs to treat obesity are not harmless. While orlistat can cause flatulence and fecal incontinence, naltrexone/bupropion occasionally causes nausea, constipation, headache, and insomnia, and should not be given to people with certain psychiatric disorders.

The incretins (liraglutide, semaglutide and tirzepatide) have, for their part, a variable effectiveness: in some people they produce notable effects and in others they are completely ineffective. In addition, they cause nausea and vomiting, and are contraindicated in people with diseases of the pancreas.

When should they be used?

Although they can be of great help, drugs are still a complement in the treatment of obesity. Physical activity is especially relevant, since both medications and diet also decrease body water and muscle mass. Only exercise allows muscle to be preserved and weight reductions to occur primarily at the expense of fat.

It must be emphasized that the treatment of obesity must be carried out under medical supervision. Among other factors, it will take into account the Body Mass Index (BMI), which is calculated by dividing a person’s weight (in kilos) by their height (in meters) squared. The use of drugs may be appropriate when the BMI is equal to or greater than 30 kg/m², or if it is greater than or equal to 27 kg/m² and the person has diabetes, hypertension, or hypercholesterolemia.

At the moment we do not have drugs that have shown losses greater than 20% of body weight. In cases in which it is necessary to achieve superior descents, gastrointestinal surgery is a therapeutic option. It is indicated when the BMI is equal to or greater than 40 kg/m² or in cases of BMI equal to or greater than 35 kg/m² if the patient has diabetes, hypertension or hypercholesterolemia.

When asked if there is a treatment to lose weight without changing life habits, the answer is no. Drugs and surgery can be a good complement to diet and physical exercise in certain cases of obesity, but by themselves they do not solve this pathology.

This article has been published in ‘The Conversation‘.