Your Body in a Weight-Reduced State

(1) An evaluation of metabolic state after participation in a program of low-calorie intake plus extensive vigorous exercise:

J Clin Endocrinol Metab. 2012 Jul;97(7):2489-96. doi: 10.1210/jc.2012-1444.
Metabolic slowing with massive weight loss despite preservation of fat-free mass.
Johannsen DL1, Knuth ND, Huizenga R, Rood JC, Ravussin E, Hall KD.  LINK to free full text

You might guess who the subjects of this study were, from the description:

  • “Once in the competition, participants were housed together at an isolated ranch outside Los Angeles.
  • The exercise component of the competition consisted of 90 min/d (6 d/wk) of directly supervised vigorous circuit training and/or aerobic training. Subjects were encouraged to exercise up to an additional 3 h/d.
  • Dietary intake was not monitored; however, subjects were advised to consume a calorie-restricted diet greater than 70% of their baseline energy requirements as calculated by the following: 21.6 kcal/kg·d × FFM (kilograms) + 370 kcal/d (23).
  • Every 7–10 d, a participant was voted out of the competition and returned home to continue their exercise and diet program unsupervised at home. Four participants remained at the ranch by wk 13, at which time they all returned home.
  • At wk 30 (7 months), all the participants returned to Los Angeles for testing, coincident with the live television broadcast.”

The outcomes (FFM is fat free mass, RMR is resting metabolic rate), from the abstract:

  • Results: At baseline, participants were severely obese (×± sd; body mass index 49.4 ± 9.4 kg/m2) with 49 ± 5% body fat. At wk 30, more than one third of initial body weight was lost (−38 ± 9%) and consisted of 17 ± 8% from FFM and 83 ± 8% from fat. RMR declined out of proportion to the decrease in body mass, demonstrating a substantial metabolic adaptation (−244 ± 231 and −504 ± 171 kcal/d at wk 6 and 30, respectively, P < 0.01). Energy expenditure attributed to physical activity increased by 10.2 ± 5.1 kcal/kg·d at wk 6 and 6.0 ± 4.1 kcal/kg·d at wk 30 (P < 0.001 vs. zero).
  • Conclusions: Despite relative preservation of FFM, exercise did not prevent dramatic slowing of resting metabolism out of proportion to weight loss. This metabolic adaptation may persist during weight maintenance and predispose to weight regain unless high levels of physical activity or caloric restriction are maintained.

Thanks to Bill Lagakos of and @CaloriesProper for reminder re: this study.


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