Can I do 5 days of fasting and on the weekends eat whatever I want?

Here are two reasons why this is not recommended:

• You are not going to adapt to a full state of ketosis.

• This provides no standard for what to eat.

Recommendation: do intermittent fasting every single day and do it correctly – start with 16:8 daily, then if you are comfortable with the ratio, start shortening the eating window a little bit at a time to notice better results.