The grapefruit diet, a short-term, very low-calorie diet, entails consuming a grapefruit before each meal. While grapefruits are a healthy source of vitamins and fibre, the diet poses risks, including nutrient deficiencies and insufficient calorie intake. This diet's restrictive nature might lead to unhealthy and unsustainable weight loss, muscle loss, and the potential for weight regain once you stop doing this diet.