If you lose your sense of smell, you'll miss more than a variety of scents. Without a good sense of smell, you may find that food tastes bland and it's hard to tell different foods apart. Loss of smell can be partial (hyposmia) or complete (anosmia) and may be temporary or permanent, depending on the cause. Even a partial loss of smell could cause you to lose interest in eating, which in extreme cases, might lead to weight loss, poor nutrition, or even depression. Some people add more salt to bland foods, which can be a problem if you have high blood pressure or kidney disease. Your sense of smell is also crucial for warning you of potential dangers such as smoke or spoiled food.

Source: Mayo Clinic