Do I base my protein intake on my current weight or my goal weight?

If you're estimating a gram goal for protein (vs. percent), it's usually OK to use goal weight. (We don't need bunchesextra protein to maintain our fat mass. It's for keeping lean mass healthy.)

Oversimplifying, the exception to that might be protein estimating methods that take goal into account in the algorithm. and give different protein numbers for losing vs. maintaining.

ech9570 wrote: »

As I understand it, you base your protein intake on the % of calories you are eating and not on your weight. So, MFP gives you a suggested daily calorie intake based on how quickly you want to reach your goal. Your daily protein intake would be 20% of that total number of calories.
I guess you could say, then, that it is based on your goal weight.
Personally, I just enter what I'm eating on a particular day and let MFP figure it out. If I'm not getting enough protein, then I can adjust what I'm eating.

Some people figure protein needs in grams, some in percents of calories. Either has pros and cons, plus possible complications.

MFP's default method is percents of calories, with a default value of 20%. That's a very mainstream approach. It's simple, yet has some limitations.

One is that people making an extreme calorie cut may get too little protein, since there's no way to get adequate nutrition on too-few calories. If I try to lose weight at 2 pounds a week, I need a 1000 calorie daily deficit. That will reduce my protein goal by 50 grams vs. when eating maintenance calories. (That's 1000 calories times 20% is 200 calories, divided by 4 calories per gram of pure protein, equals 50 grams.) 50 grams is a pretty significant fraction of most people's protein needs in absolute terms. It may or may not be OK depending on a variety of factors.

Many extreme weight loss methods (such as those that may be used under close medical supervision before bariatric surgery) utilize high protein diets, which typically would be significantly more protein than 20% of calories. That helps keep muscle loss to a minimum alongside fat loss.

The other method, estimating in grams, uses body weight in calculations more directly. Some people prefer this method. I suspect OP was asking about this kind of method. As an example, a common rule of thumb is 0.6-0.8 grams daily per pound of body weight (maybe even more if serious about building muscle). In a calculation like that, it makes sense to use goal bodyweight. There are various ins and outs of what the "X per pound" should be, but that's not really the point here.

Personally, I prefer to estimate protein needs in grams, for a variety of reasons, but I'm not arguing that it's universally essential to do it that way.