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About Dr. Rosaasen

Jonathan Rosaasen, MD is co-owner and lead physician of Rosaasen Family Medicine, a state-of-the-art family medicine practice in Thousand Oaks, California that serves residents of all ages from communities across Ventura County and the greater Los Angeles area.


Dr. Rosaasen is a board-certified family physician who specializes in weight loss and nutrition management. He believes that active participation and patient education are essential to achieving and maintaining good health. Dr. Rosaasen’s approach to weight loss involves creating a judgment-free partnership with his patients, and encouraging the small lifestyle changes that can lead to permanent healthy habits. With more than 15 years of experience in the medical field, Dr. Rosaasen understands that many factors influence an individual’s physical health, and he thoroughly enjoys helping his patients establish attainable goals, and then reach them.  


Dr. Rosaasen earned his medical degree from the Loma Linda University School of Medicine in Loma Linda, California. After graduating from medical school, he went on to complete his Family Practice residency at Kaiser Permanente in Riverside, California.

He and his wife, Dr. Amanda Rosaasen, are the proud parents of three bright and compassionate young children (a son and two daughters). Together, they enjoy riding bikes, skiing, and spending time in the water.

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