Kate Beckinsale has opened up about living with a rare autoimmune disease after years of public scrutiny over her weight. In a 13-part video shared on social media, the 53-year-old actress detailed her diagnosis of mast cell disease and mast cell activation syndrome (MCAS), her symptoms, and her hope that sharing her experience will help others facing similar challenges.
Beckinsale's candid revelation
Beckinsale began the video by addressing the relentless criticism she receives online. 'As I’m sure you’re aware, anytime I post a photo of myself, I receive an enormous amount of comments telling me how disgusting I look and I’m anorexic or I’m on meth or that I’ve lost so much weight,' she said.
She then revealed the personal losses that have compounded her struggles: 'First off, I’ve lost my entire family, except my precious daughter, in a short amount of time.' Her mother, Judy Loe, died in July 2025 after a cancer diagnosis, just 18 months after her stepfather Roy Battersby passed away in January 2024.
Beckinsale explained that she was diagnosed with mast cell activation syndrome 16 years ago, thanks to a perceptive GP in London who referred her to a specialist in New Jersey. 'This is something that I was diagnosed with 16 years ago, and I was really, really lucky that I had an amazing GP in London who called it and sent me to, at that point, the one guy in the world in New Jersey who was the expert in that,' she said.
Understanding mast cell activation syndrome
Mast cell activation syndrome is a condition where mast cells—a type of white blood cell—release chemicals too frequently or in response to triggers that are not typically harmful, such as certain foods or environmental chemicals. This can cause a wide range of symptoms affecting multiple body systems. Beckinsale described her stomach as 'ground zero' for how the disease manifests in her case.
The condition is often underdiagnosed, and Beckinsale stressed the importance of awareness. She referenced the losses of Caroline Flack and Chadwick Boseman, as well as the online distress of figures like Perez Hilton and the withdrawal of stars like Ariana Grande, to highlight that 'we don’t know what’s going on in people’s lives.'
She urged compassion: 'Treat people just how you’d like to be treated yourself, give people a little grace. If you don’t have anything nice to say, maybe don’t say anything.' Calling it 'not necessary for everyone to know your opinion on what somebody else’s body looks like,' she added, 'You don’t want to be the last straw for somebody, you don’t want to be the thing that makes them more sick, just keep going, it’s not hard.'
Previous disclosures and broader impact
This is not the first time Beckinsale has spoken about her condition. In May 2024, she responded to comments about her weight by disclosing she had a 'severe flare-up' of mast cell activation syndrome. At the time, she said, 'What you think of my appearance and how I should look, independently of any circumstances in my life and my family is not important. I am trying to survive what feel like unbearable losses, reactivated PTSD from discovering my very young father’s almost dead body as a very young child alone in the night, and working to support the family I have left.'
In the comments of her latest post, she elaborated on what triggered her condition: 'For me it was a horrific marriage combined with glandular fever, and that’s what tipped it. I had not had a single allergy as a child, even though I’ve had a lot of trauma as a child, but I was pretty much tied up for it, and that sent me over the edge.'
Beckinsale is not alone among celebrities in speaking out about MCAS. Game of Thrones star Emilia Clarke has also recently opened up about how the autoimmune disease has shaped her life, bringing further attention to this often-misunderstood condition.
