The weight loss industry is projected to reach USD$ 278.95 billion worldwide by 2023. Weight loss companies devote a large part of their budget for advertising their products. Unfortunately, as revealed by the Federal Trade Commission (FTC), there are many deceptive ads. The effect of weight loss advertising on consumer’s diet and eating behavior is so large that it has been proposed a causal relationship between advertising and diet. Adolescents, women with appearance concerns, and obese people, are the most vulnerable consumers for this kind of advertising. Within the Internet, most weight loss products are advertised under algorithmic rules. This algorithmic regulation refers to the online advertising being established by a series of rules (i.e., algorithms). These algorithms collect information about our online identity and behavior (e.g., sociodemographic characteristics, online searches we do, online content we download, “liked” content, etc.), to personalize the content displayed while we browse the Internet. Because of it, this algorithmic regulation has been described as a “filter bubble”, because most content we see on the Internet is reflecting our idiosyncratic interests, desires, and needs. Following this paradigm, this study presents a research protocol to experimentally examine the effect of online weight loss advertising in the attention (using eye-tracking) and physiological response (using facial electromyography) of women with different levels of body dissatisfaction. The protocol describes the methodology for: participants’ recruitment; collecting weight loss ads; and the experimental study, which includes the stimuli (ads) and the responses (eye fixations and facial muscles activity).