Losing weight is high on many people’s plan to improve their health as spring approaches. But shedding pounds and keeping them off isn’t easy. Or quick. Obesity is associated with serious health risk, including diabetes and heart disease. It can also seriously diminish your quality of life. Nearly 40 percent of American adults are obese (have a body mass index of 30 percent or more), according to the National Institutes of Health. Amanda Smith, a registered dietitian at Novant Health Bariatric Solutions in Winston-Salem, examined five common weight-loss mistakes, and some better alternatives. 1. Setting goals that aren’t realistic It’s easy to tell yourself “I’ll lose 30 pounds by summer,” or “I’ll be the slimmest person at the high school reunion.” Solution: Set smaller, incremental goals. “Realize that even with small amounts of weight loss, you can see benefits to your health, such as lower blood pressure and better blood sugar control for patie