Pre-exposure prophylaxis, commonly known as PrEP, is a preventative medical strategy for individuals who do not have HIV but are at a higher risk of acquiring it. This medication, taken as a pill or injection, works by blocking the virus from establishing itself in the body if exposure occurs. As with any medication, individuals considering PrEP often have questions about potential side effects, with weight changes being a frequent concern.
Addressing the Weight Gain Question
Significant or clinically relevant weight gain is generally not a common side effect for most individuals taking PrEP. While some people might experience minor weight changes, these are typically small and may not be directly attributable solely to the medication. It is important to differentiate between the two main oral formulations: tenofovir disoproxil fumarate/emtricitabine (TDF/FTC, known as Truvada) and tenofovir alafenamide/emtricitabine (TAF/FTC, known as Descovy). Studies have observed slightly more weight gain with TAF/FTC compared to TDF/FTC, though these changes are modest. TDF/FTC has even been associated with slight weight loss in some users.
What the Research Shows
Scientific evidence indicates that any weight changes linked to PrEP are typically modest and often stabilize over time. For instance, a large analysis of clinical trials reported that participants gained an average of about 2 kg over their first two years on treatment, with much of this occurring in the first year. One study, the ADVANCE trial, found that individuals gained between 0.5 to 6.4 kg over 48 weeks, with differences observed across various drug combinations. Another analysis found that approximately 17% of participants gained at least 10% of their body weight over one to two years. These observed increases are generally within the range of normal weight fluctuations and are often not clinically significant for many individuals.
Potential Contributing Factors
Several factors might contribute to weight changes observed in individuals taking PrEP, even if the medication itself is not a direct cause of substantial gain. One explanation is a “return to health” effect, where individuals who were in poorer health or underweight before starting PrEP may gain weight as their overall health improves. Lifestyle habits, such as changes in diet or activity levels after starting PrEP, can also play a role. Fluid retention is another factor that can cause temporary weight fluctuations. Although less common, some individuals report changes in appetite, possibly linked to components like tenofovir in certain PrEP medications.
Managing Your Weight on PrEP
For individuals concerned about or experiencing weight changes while on PrEP, several practical strategies can help. These include maintaining a balanced diet rich in whole foods, fruits, vegetables, and lean proteins. Regular physical activity, such as walking, running, or cycling, also contributes to effective weight management. Ensuring adequate hydration and communicating openly with a healthcare provider about any weight concerns are also important. The benefits of PrEP in preventing HIV transmission outweigh the potential for minor weight changes.