You can't.

Eat plenty of fruits, vegetables, meats, and fish.

Diet may seem unrelated to your hair, but it makes a huge difference. Diet also has the added benefit of improving your body at the same time.

Since hair is made of protein, make sure you're getting plenty of protein in your diet.

Some proteins to consider incorporating … Read more

If by increase you mean grow faster, you can't. Hair grows about 1/2 inch a month. That's it nothing you can do will speed that up. It's all in Mother Natures hands.

For short term you can add extensions or wear a wig..