Yīshēng jiànyì tā tōngguò yùndòng hé yǐnshí jiǎnzhòng.
The doctor advised her to lose weight through exercise and diet.
Tips
usage
减重 focuses on the number on the scale; 减肥 (lose fat) is the more casual catch-all term. Gyms and medical clinics prefer 减重 because it sounds clinical and measurable.