I am 179 pounds.

I am currently in week 2 of P90X3 again.

I want to build muscle, but ultimately get closer to 170lbs by the end-ish of this round of X3 which would be ~90 days. I guess it's also not as much about weight as it is burning fat too.

MyFitnessPal says I should eat 1990 calories per day, but to me that seems low.

I'm tying to figure out the right amount to eat to lose weight (or burn fat) and still build some muscle.

Any suggestions?


  • Do you know your existing body fat percentage? Much harder to drop fat when you're already low. But north of 20%, 9lb in 90 days is aggressive but do-able. That 1900 is probably quite close.
    – Eric
    Commented Jan 12, 2015 at 21:20
  • Currently ~%16.9 Commented Jan 14, 2015 at 23:01

1 Answer 1


Well let's assume you want to lose 9 pounds of fat, because if you gain muscle on top of that it throws everything out of whack(burn more calories with more muscle, you gain weight with muscle, etc). So let's just say you want to be 9 pounds lighter now, and what that means in terms of your caloric intake and how much you need to burn off.

Metabolic rate isn't the same for everyone, but generally with your weight(and assuming you're around 6 feet tall), will be roughly 2000, maybe a little less.

3500 calories per pound * 9 pounds = 31,500 Cal burned total. You want to do this over the course of 90 days. Welp, let's divide by 90. 31,500/90 = 350.

So you need roughly a 350 daily calorie deficit over the course of 90 days to lose 9 pounds of fat. You'll gain muscle and lose fat gradually during this period, so the numbers get skewed slightly and inconsistent, but if you're in the ballpark of that number for your average calorie deficit you'll be fine.

Another thing to note is you won't build that much muscle, at least not as much as you might hope. The body needs fuel to build muscle, and the more fuel it has the more effectively it builds the muscle. Since you're going to be at a deficit for fuel, you won't build muscle nearly as effectively(which is fine if burning fat is what you want, it's impossible to do both optimally).

I just want to add that these numbers are not specific, and not necessarily accurate for you as an individual, it's just what the averages would be among people. You have to gauge your results over time and see how you might need to adjust as well.

  • To the person that downvoted, what in particular about the answer did you not agree like? I personally don't see anything wrong with the answer.
    – Moses
    Commented Jan 12, 2015 at 22:03

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