Trans fats, like those found in many fried foods, vegetable shortening, cookies, crackers, margarine, chips, and baked goods, contribute to greasy hair and skin without providing any nutritious value to your body. Try to limit these foods entirely, and reduce the amount of saturated fats you consume through meat and dairy products.  High carbohydrate, high sugar foods also cause your body to produce more sebum, or thick oil, on your skin – including your scalp and hair. Baked goods and foods high in processed white flour (white breads and pastas) should be replaced with whole grains, low-starch vegetables, legumes, and fruit. Continue eating sources of good fats, or foods with essential fatty acids such as nuts, seeds, fatty fish, and unrefined whole grains. These foods provide your body with fats that it needs, and deficiencies in these fats can actually have a negative impact on your skin and hair health. Touching your hair transfers oils from your fingers and hands onto your hair. Try to touch your hair as little as possible when you’re not styling it.  If you need to fix your hair, use a clean brush or comb instead of your fingers. Dry heat, much like hot water, tends to strip hair of its natural oil, causing it to overcompensate by producing even more oil. Allow your hair to air-dry after washing it as often as possible. Brushing takes grease from the scalp and moves it down the hair follicles, so you should take hair to clean your hairbrush regularly. Remove hair from your brush as often as possible. Clean your brush once a week by squirting a few drops of dish soap into it, adding water, and rubbing the ends of the bristles with the soap suds. Rinse all the soap from your brush and let it air-dry. Because brushing moves oil down your hair, you should also avoid overbrushing. Try to brush your hair only when it is tangled or when you are styling it for the day.

TL;DR in Vietnamese:
Áp dụng chế độ ăn ít carbohydrate và chất béo chuyển hóa. Hạn chế chạm vào tóc. Càng ít sấy tóc càng tốt. Làm sạch bàn chải tóc.