On the April 9, 2025, episode of The Megyn Kelly Show, Dr. Mark Hyman, co-founder of Function Health, spoke about the benefits of ketogenic diets. Dr Hyman talked about how increasing fat and reducing carbohydrates may help treat chronic illnesses, including type 2 diabetes, Alzheimer’s disease, cancer, and even mental health disorders.
“When you restrict carbohydrates and increase fats, you actually switch basically from a gas-burning car to an electric car, and it's clean burning,” Mark Hyman said. “Now we're finding it's effective for reversing type 2 diabetes, treatment for Alzheimer's, for cancer.”
Mark Hyman’s car analogy refers to this metabolic switch. He compared the fat-burning state to an electric vehicle, calling it “clean burning,” and suggested that this process could be linked to positive outcomes for people suffering from chronic diseases.
He also referenced Pulitzer Prize-winning author and oncologist Dr. Siddhartha Mukherjee, who is currently researching the use of ketogenic diets for late-stage cancer treatment.
Mark Hyman explains the benefits of daily walking
Cleveland Clinic's Senior Medical Advisor, Dr. Mark Hyman, recently took to Instagram to share findings from two major studies, emphasizing the profound health benefits of walking, even in small amounts.
Sharing the highlights of the research, Hyman wrote,
"A study published in The Lancet tracked over 47,000 people for seven years and found that just 6,000 to 8,000 steps a day for those over 60, and 8,000 to 10,000 steps for those under 60, was associated with a lower risk of death."
He emphasised that consistent movement, even as simple as a short daily walk, can dramatically impact long-term health and longevity.
Dr. Hyman encourages people to start small and stay consistent:
"It doesn’t have to be 10,000 steps. Start where you are and build from there."
Dr. Mark Hyman told Megyn Kelly that toxins, environmental factors, and poor nutrition may contribute to chronic diseases, even in children. He discussed how dietary changes can improve brain function and manage illness. He also talked about the ketogenic diet’s impact on mental health and cancer, highlighting which foods to eat or avoid.
Concerns about weight loss drugs

Dr Siddhartha Mukherjee, who Dr Mark Hyman spoke about during the video, is one of several researchers who are studying ketogenic diets in the context of cancer. While results on it are still awaited, the diet has a history of clinical use, most notably for managing drug-resistant epilepsy.
Hyman referenced Robert F. Kennedy Jr. and the Make America Healthy Again (MAHA) campaign, highlighting opposition to nutritional advocacy movements.
He also addressed GLP-1 receptor agonists like Ozempic, stating that while they may cause weight loss, they do not necessarily improve metabolic health without additional lifestyle changes.