Most lenders require buyers to have genuine savings, if you are buying over 80%.
This shows you are able to be responsible with your finances long term and not just when applying for the loan. Your spending habits are determined by the lender when they receive your bank statements dating back 6 months. To prove genuine savings you must have the funds in your account for 3- 6 months, if you are using these funds a deposit. Not all lenders require this, however most do.