Is this a healthy "fast"? or too restrictive and will end up with weight gain?

not eating can only be a health risk; all the foods you listed are great, drinking plenty of fluids and eating small amts every 2 - 3 hrs is the best way to consistently lose wt; plus keep your glucose levels at a consistent level. There is nothing worse then being hungry and feeling weak. It is unhealthy. You won't have the energy to exercise and you will lose muscle mass as well as wt loss.