Social media is an endless source of health and fitness content , with videos, challenges, before-and-after photos, and promises of miracle supplements shared by so-called content creators, influencers and celebrities. This advice often seems helpful: it uses simple language, reaches our phones instantly, and show visible results. However, it is important to remember that what works for one person may be unsuitable, or even dangerous, for someone else. Some content is shared by qualified professionals who help clarify doubts and encourage regular physical activity. However, social media also spreads overly restrictive diets, excessive training programmes without supervision, and the misleading idea that a “perfect body” can be easily achieved by anyone. For example, a high-intensity workout may benefit someone who is properly prepared, but it can become risky if followed by anyone without prior assessment. This illustrates how recommendations that appear sensible can have negative consequences in real life. Being able to assess the quality of information is increasingly an essential skill for protecting your health. What are the most common types of content? A wide variety of fitness and health content circulates online: quick exercise tips, trendy diets (such as radical detox or low-carb plans), viral challenges, and “transformation” promises illustrated with before-and-after photos. Many of these posts combine personal opinions, isolated success stories, and eye-catching images, but rarely include explanations based on scientific evidence or support from qualified professionals. In addition, many posts promote supplements and supposedly “natural” products for muscle gain or weight loss, often linked to commercial partnerships that are not fully transparent. As a result, while the information may seem abundant and convincing, the source and quality of these messages vary greatly, requiring readers to adopt an increasingly critical and cautious approach. Risks associated with trends and challenges Following fitness advice without considering the context can lead to several problems. From a physical perspective, very intense or advanced exercises performed without adequate preparation or supervision increase the risk of muscle and joint injuries, as well as excessive fatigue. For instance, popular high-effort training methods such as HIIT (high-intensity interval training), although potentially beneficial, can become dangerous when applied incorrectly, especially in people with pre-existing health conditions. Extreme diets may also lead to nutritional deficiencies, eating behaviors disorders, and emotional distress. From a psychological and behavioral standpoint, promises of “guaranteed results” and images of “perfect bodies” create unrealistic expectations, leading to frustration and low self-esteem. This may even cause people to abandon exercise programmes, medical treatments, or professional advice. In some cases, adherence to highly restrictive diets or supplements promoted online can delay the search for qualified support and may interfere with prescribed medications. This makes a critical attitude towards such content particularly important. Who may be more vulnerable? None of this means that people who seek fitness and health content on social media are naïve. Many people, including patients, use these platforms because they want quick answers presented in simple language. However, certain situations require additional caution. Beginners in exercise, people with chronic illnesses, persistent symptoms or other health problems, pregnant women, and individuals seeking rapid body changes after an obesity diagnosis or a period of significant body dissatisfaction may be more vulnerable to following unsafe advice. People with lower health literacy or limited access to professional support are also more likely to rely on online information. Studies have additionally shown that, in many contexts, women experience greater social pressure to adhere to strict training and dieting routines. In short, the more concerned we are about our health and the more we desire quick results the more likely we are to accept recommendations without questioning them. True or false is not enough Many people evaluate fitness and health posts simply as “true” or “false.” In reality, things are more complex. Information can be technically correct and still not apply to the person reading it. For example, some studies show that 30 minutes of daily walking improve cardiovascular health in healthy older adults. However, that does not mean that someone with severe heart disease should simply copy that routine or attempt something even more intense. Likewise, an exercise demonstrated correctly by a coach on social media is not automatically safe for everyone. Therefore, instead of asking only whether advice is correct, it is important to consider who it applies to, under what circumstances, and how it should be implemented. This requires considering individual health status, personal limitations, lifestyle, and motivations. More reliable content usually acknowledges warnings and exceptions, whereas riskier messages tend to promote universal, risk-free solutions. Assessing reliability with 5 questions Given the huge amount of fitness and health information on social media, having a simple framework to evaluate what we see can be extremely helpful. These five questions act as practical filters. Additional warning signs There are also warning signs that should raise concerns when evaluating health and fitness content. Conspiracy-style claims such as “doctors don’t want you to know this,” suggestions to stop prescribed medications, the exclusive use of before-and-after photos without supporting data, individual testimonials presented as the only “evidence”, generic attacks on professionals (“nutritionists are wrong”), and absolute statements that ignore potential risks are all indicators of poor-quality information. Naturally, these signs alone do not prove that content is entirely false, but they indicate that the critical questions outlined above should be applied even more carefully before following any recommendations. When to seek professional advice Whenever you have questions about symptoms, health concerns, exercise workouts, diets, or supplement use, the safest option is to speak with a doctor, registered dietitian, exercise physiologist, or another qualified professional. This is particularly important if you have chronic conditions, persistent symptoms, or plan to begin an intense training workout without supervision. Professional guidance ensures that each situation is assessed individually and that recommendations are tailored to a person's specific circumstances. In summary Social media can be a valuable source of information and motivation, but it requires a critical mindset : not everything that is said is true, and not everything that is true is appropriate for everyone. It is always worth asking who is communicating the message, what evidence it is based on, whether limitations are acknowledged, whether commercial interests are involved, and whether individual differences are considered. By using five questions as a filter before following any fitness trend, and seeking professional advice, when necessary , we can make better decisions about our health and increase the likelihood that what we learn on social media will genuinely benefit our lives. Sources: Peelo Dennehy D, Murphy S, Foley S, McCarthy J, Morrissey K. Keeping fit & staying safe: a systematic review of women’s use of social media for fitness . Intern J Human-Computer Stud 2024;192:103361. Thomas DD, Xu L, Yu B, Alanis O, Adamek J, Canton I, Lin X, Luo Y, Mullen SP. Physical activity misinformation on social media: systematic review . JMIR Infodemiology 2025;5:e62760. Author : Hugo Vieira Pereira (exercise physiology) The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
