How fast can fat be burned? I am not asking about how quickly weight can be lost but how much of a human's calorific need can be met by fat alone? Is it healthy to work at the maximum power output of fat for sustained periods?


Although it changes from person to person (weight), approximately 60-85% of maximal heart rate are accepted as fat burning zone. If you keep your intensity (lower is better) between above mentioned intervals, up to 70% of the calories burned can come from fat . This article may somewhat help you. Fat Burning During Exercise

how fast? do the math :-) every 45 minutes your run you lose 1 pound

  • That sounds very optimistic. Sorry. A kilogram of raw fat has 9300 kcal energy stored for the body. Therefore you would have to burn 4200 kcal in 45 min of runing. I guess that means running around near the sound barrier – Julian Mar 14 '16 at 9:05
  • Yes you are right :-) But in the answer I wrote; you lose 1 pound, not 1 pound of fat. May be I should have been more clear about it. Thanks for the correction. – bantandor Mar 14 '16 at 9:13
  • I should try. I sweat alot uring running. So I guess I can reach 1 Kilo per 45 minutes. But the weight loss will be 90-99% water then ( and a lot of pride when I realize how slow my running is) – Julian Mar 14 '16 at 9:15

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