Congratulations on making the sometimes difficult choice to make regular exercise and healthy eating choices a part of your regular routine. It does take a commitment to do this right, but it is absolutely the best thing you can do to stay healthy for the long run. Regarding your question, the best thing to do is to discuss this issue with your doctor
. Generally speaking, it can be helpful to stay motivated with a lifestyle diet to make sure that you give yourself the chance to take "breaks." In general, moderation is the key. You mention pizza, fried foods, sweets, and alcohol as being included in some of your cravings--it is probably a good idea that when you do take a break from strictly healthy choices that you don't indulge in all of these things at the same time. In general, thinking about one day a week to take a break from a strict dietary plan is reasonable. However, if you eat well during the week and then completely let go for the weekend you are not likely to make the kind of healthy progress that you'd like to do. Again, the best thing to do is to consider seeing your doctor to discuss this and to obtain a referral to a nutritionist or dietician who can discuss a healthy way to include "breaks" into your eating plan.