【BMJ圣诞特刊】减肥后那些脂肪都去哪里了？

BMJ本期圣诞节专期的这篇文章很有趣。
http://www.bmj.com/content/349/bmj.g7257

减肥后那些脂肪都去哪里了？调查显示很多医生，营养师，健身教练都错误地认为脂肪被燃烧成热量/能量排出去了。这篇文章帮我们复习了一遍基本生化知识，结论是：脂肪通过最终产物CO2从肺部排出体外了。可以说减肥者就是个碳排者。



Fig 1 Responses of a sample of doctors, dieticians, and personal trainers to the question
“When somebody loses weight, where does it go?” (Correct answer CO2)



Fig 2 When somebody loses 10 kg of fat (triglyceride), 8.4 kg is exhaled as CO2. The remainder of the 28 kg
total of CO2 produced is contributed by inhaled oxygen. Lungs are therefore the primary
excretory organ for weight loss. (This calculation ignores fat that may be excreted as ketone bodies
under particular (patho)physiological conditions or minor amounts of lean body mass,
the nitrogen in which may be excreted as urea)

......
Our calculations show that the lungs are the primary excretory organ for fat. Losing weight requires unlocking the carbon stored in fat cells, thus reinforcing that often heard refrain of “eat less, move more.” We recommend these concepts be included in secondary school science curriculums and university biochemistry courses to correct widespread misconceptions about weight loss.

Where does the fat go?