Is obesity actually classified as a chronic disease, or is that just a way to make it sound more serious?

It's an actual formal classification, not just framing. The Canadian Medical Association officially declared obesity a chronic disease in 2015, and several provinces (Saskatchewan, Yukon, Ontario, Alberta) have since followed with their own recognition. The World Health Organization and American Medical Association have made similar classifications. It reflects a clinical understanding that obesity is a complex condition involving abnormal fat accumulation that impairs health and increases risk of long-term complications, not a rhetorical choice. References: https://obesitycanada.ca/healthcare-professionals/adult-clinical-practice-guideline/