The caveat to everything I'm about to say - always follow your doctor's advice. The following is for informational purposes only.
You don't have to meet your protein needs to lose weight, your weight loss will happen with overall caloric deficiency. Protein also doesn't actually build or maintain muscle on its own - only exercise can do that - but to form healthy new tissues, your body needs protein. One of primary reasons for having adequate protein post-surgery is for healing. Protein is very important for tissue growth and repair.
It is an important component of every cell in the body. Hair and nails are mostly made of protein. Your body uses protein to build and repair tissues. You also use protein to make enzymes, hormones, and other body chemicals. Protein is an important building block of bones, muscles, cartilage, skin, and blood.
Obviously, right after surgery you are still obese and have much more muscle and other tissues in your body, and you are healing from surgery. Protein requirements are generally higher to maintain that healthy tissue. The minimum that is usually recommended is 60g, which is probably a decent average for most bariatric patients. The recommendation for some patients may be more at first, but as weight/fat decreases over time, so does your protein intake requirements. A general rule of thumb is to multiply your body weight by 0.3 and shoot for that (or whatever your doctor recommends). For myself, that puts my protein goal at 76g. I recalculate every 10 lbs I lose. Obviously, extremely morbidly, obese people, the multiplication factor will be a little out of whack because it would be practically impossible to eat that much protein, so it really comes back to your surgeon's and dietician's recommendation.
If you reach your goal weight then the common protein requirements are:
- Growing teen boys and active men get enough protein in seven ounces per day (about 50g).
- For children between 6-12, teen girls, active women and most men, about six oz (about 42g)
- Children under 6, most women, and some older people, five ounces is plenty (about 35g)
These are all averages, of course. Extra protein isn't harmful, it's just a waste of calories because your body won't use it if it doesn't need it for anything, but too little protein can detrimental, although I don't think there is too much to worry about if you are a few grams short. Your weight loss will catch up to it. I would just try to get as close to whatever your doctor recommended as possible and maintain that until you start losing enough weight to consider adjusting the amount.
So, I guess the short answer should have been: get as close as you can to your doctor's recommendation, it is beneficial for your recovery and good health moving forward. I'm sorry I rambled on longer than that.