Obesity has become one of the main threats to public health worldwide. Its prevalence continues to increase in both industrialised countries and low- and middle-income countries, with alarming figures among adults. This clinical reality is not trivial: obesity is associated with an increased risk of type 2 diabetes, cardiovascular disease, certain types of cancer, cognitive impairment, dementia and premature death.
From clinical nutrition, we know that obesity is a chronic, complex, and multifactorial disease, determined by the interaction between biology, environment, behaviour, socioeconomic context, and psychological factors. Therefore, its treatment is rarely simple or definitive.
In this scenario, weight control medications, particularly GLP-1 receptor agonists, have taken centre stage and are often presented as a highly effective solution. However, the latest scientific evidence calls for a more cautious and nuanced approach.
What are GLP-1 receptor agonists?
Glucagon-like peptide-1 (GLP-1) receptor agonists are drugs that mimic the action of an intestinal hormone released after food intake. At the physiological level:
- They increase glucose-dependent insulin secretion
- They reduce glucagon secretion
- They delay gastric emptying
- They increase the feeling of satiety
- They decrease appetite
As a result, many people spontaneously reduce their energy intake, facilitating clinically significant weight loss.
These drugs were initially developed for the treatment of type 2 diabetes and, over time, have been shown to have additional benefits on body weight and cardiovascular risk.
How long have they been used and for whom are they indicated?
GLP-1 receptor agonists have been used in clinical practice for almost two decades in the context of diabetes. Their specific use for obesity has become established in recent years, with formulations and doses adapted to this objective.
They are currently indicated for:
- People with a body mass index ≥30 kg/m², or
- People with a BMI ≥27 kg/m² who have comorbidities related to excess weight
They should always be prescribed as part of a comprehensive medical approach, and not as an isolated intervention or for purely aesthetic purposes.
What the latest evidence tells us
Clinical trials have shown that these drugs allow, on average, moderate but clinically relevant weight loss. However, according to a meta-analysis published in the journal The BMJ on 7 January, the long-term results require critical interpretation.
The data show that, after several months of treatment, discontinuation of the drug is associated with a gradual recovery of body weight. In fact, weight gain after withdrawal is consistent enough that, in many cases, weight returns to near-baseline values within a relatively short period of time.
From a physiological point of view, this phenomenon is not unexpected: when the drug is withdrawn, its effect on appetite and satiety regulation disappears, while the biological mechanisms of body weight defence are reactivated.
Why many people abandon treatment
Observational evidence and clinical experience agree that a considerable proportion of people discontinue treatment during the first year. Among the most common reasons are:
- High cost
- Gastrointestinal side effects
- Fatigue associated with chronic treatment
- Rejection of the injectable route
- Unrealistic expectations of permanent results
All of this reinforces the idea that these drugs cannot be considered a definitive solution for obesity.
Does it make sense to lose weight if you then regain it?
One of the most relevant conclusions drawn from the scientific evidence is that significant weight loss, even if not completely maintained over time, can provide lasting metabolic benefits in people with obesity.
Several studies have shown that moderate reductions in body weight decrease the risk of developing type 2 diabetes and improve metabolic parameters, even if some of the weight is subsequently regained.
However, this benefit is not universal. In people with a normal body mass index, intentional weight loss has been associated with an increased metabolic risk, probably due to greater loss of lean mass and weight regain characterised by a disproportionate increase in fat mass.
How to optimise the use of these drugs
From an evidence-based nutritional perspective, GLP-1 receptor agonists should be used:
- As a complement, never as a substitute, to dietary intervention and lifestyle change
- Integrated into a nutritional plan that prioritises:
- Adequate protein intake
- Preservation of muscle mass
- Diet quality, beyond calorie restriction
- Accompanied by physical exercise, especially strength training
- With nutritional education from the start of treatment
The goal should not be solely weight loss, but improved metabolic and functional health.
How to reduce the risk of weight regain
Preventing weight regain after discontinuing drug treatment remains one of the major challenges. Some evidence-based strategies include:
- Building sustainable habits while the drug is active
- Avoiding overly restrictive diets
- Protecting muscle mass
- Maintaining nutritional follow-up after discontinuation
- Accepting that obesity is a chronic disease, with possible relapses
Withdrawal of the drug should be understood as a planned transition, not the end of treatment.
Conclusion: useful tools, not miracle solutions
GLP-1 receptor agonists are not a magic cure for obesity, but they can be valuable tools in well-selected individuals and within a comprehensive therapeutic approach.
The basis of treatment remains a healthy diet, an active lifestyle, and public health policies that facilitate healthy choices, such as clear food labelling and affordable access to fresh produce, among others.
As nutrition professionals, our role is to accompany, educate, and contextualise, remembering that true success is not just about losing weight, but gaining long-term health.