A 40 30 30 diet, also known as the Zone Diet, is a meal plan where 40% of the calories come from carbohydrates, 30% from protein, and 30% from fat. The diet emphasizes eating lean proteins, healthy fats, and low-glycemic carbohydrates to keep blood sugar levels stable. A typical meal on the 40 30 30 diet may include grilled chicken, spinach and vegetable salad with olive oil and balsamic vinegar dressing, and a small amount of brown rice. The diet recommends small, frequent meals throughout the day to maintain balance and prevent blood sugar spikes.