Avocados are an excellent option on a keto diet. They have about 30 grams of fat (depending on the size), and two-thirds of this is monounsaturated fat, which improves good cholesterol levels and lowers bad cholesterol. They are high in fiber. Avocados are also a source of protein, potassium, and magnesium. They also contain folate. This B vitamin has decreases homocysteine levels, an amino acid that is linked to heart disease.