Foy reported experiencing significant weight loss despite increased food intake, a symptom that eventually prompted medical evaluation. Diagnostic testing later confirmed the presence of intestinal parasites. While she did not disclose the exact species involved, she stated that treatment required dietary changes, including complete avoidance of caffeine, which she continues to follow.
Claire Foy, The Crown star, 41, told hosts Jessie and Lennie Ware during an appearance on The Table Manners Podcast,
I kept losing weight, and I didn't know what was going on. But also, like, no matter how, I was just like, I'm eating everything. I was so hungry.
Claire Foy
According to Foy, the infection likely began several years earlier during travel to Morocco. The prolonged duration between exposure and diagnosis reflects a well-documented challenge in parasitic diseases, where symptoms can remain nonspecific or mild for extended periods.
Anyway, so that's why I gave up caffeine because I had to give up. I didn't want to take like really hardcore antibiotics and stuff like that first. I took all this gross stuff. And part of that was giving up caffeine.
Claire Foy
Intestinal parasitic infections commonly present with symptoms such as weight loss, abdominal discomfort, diarrhea, and nutritional deficiencies. These manifestations overlap with many non-infectious gastrointestinal conditions, contributing to delayed diagnosis. In travelers, symptoms may appear long after exposure, further complicating clinical suspicion.1
Parasitic infections occur when protozoa or helminths enter the human body, most often through ingestion of contaminated food or water or via fecal-oral transmission. Regions with limited access to clean water and sanitation carry higher transmission risk, although travel-associated infections can occur globally.1
Types of parasites: Common intestinal parasites include protozoa such as Giardia duodenalis and Entamoeba histolytica, as well as helminths like Ascaris lumbricoides and hookworms.
Transmission: Infection typically occurs through contaminated food, water, or poor hand hygiene.
Clinical features: Symptoms range from asymptomatic carriage to chronic diarrhea, malabsorption, anemia, and unintended weight loss.
Diagnosis: Stool microscopy remains the primary diagnostic method, though molecular tests improve detection accuracy.
Treatment: Antiparasitic medications are effective in most cases when appropriately targeted.
Public health burden: Parasitic infections affect more than one billion people worldwide and remain a significant global health concern.1
References:
1. Martins-Duarte ES. Parasites and Infection: Strategies to Control, Diagnose, and Treat Parasitic Diseases. Microorganisms. 2025 May 29;13(6):1254. doi: 10.3390/microorganisms13061254. PMID: 40572141; PMCID: PMC12194987.
