Wednesday, October 16, 2024
Research

Can weight loss slow your Metabolism?

Gayan Perera

(Nunes et al., 2022)

Your body requires energy (burns Calories) to maintain body weight. Even maintaining fat mass requires energy. Therefore, the heavier you are more energy (Calories) you need to maintain body weight.

If you lose weight, your body needs to burn fewer Calories to maintain your new body weight. A smaller body requires less energy. But in some cases, this decrease in energy expenditure is larger than what can be explained by the loss of body weight. This is called “adaptive thermogenesis.”

Adaptive Thermogenesis is when your body reduces its heat production to conserve energy to keep you from starving when food is scarce. It makes sense from a survival point of view, but it can be a problem if you are trying to lose weight.

Nunes et al., 2022 examined,

  1. If Adaptive Thermogenesis (AT) occurs after moderate Weight Loss and if AT persists after a period of weight loss maintenance.
  2. If AT is associated with changes in body composition, hormones, and energy intake.

94 sedentary former elite athletes were randomized to a 12-month lifestyle intervention group or a waitlist control group. The participants in the lifestyle intervention underwent a 4-month weight-loss period followed by an 8-month weight maintenance period.

Results:

  • Participants in the intervention group lost 4.8kgs during the 4 months weight-loss period and kept it off at the 12th month (end of the study). The measured (actual) Resting Energy Expenditure was 85 Calories lower than the Predicted Resting Energy Expenditure at 4 months and 72 Calories lower at 12 months. So REE only went up by 13 Calories after 8 months of weight loss maintenance.
  • Participants with bigger energy deficits had higher adaptive thermogenesis at 12 months.
  • Participants with adaptive thermogenesis experienced less weight loss and fat loss and had a lower baseline energy intake.

Reference:

Nunes CL, Jesus F, Francisco R, Hopkins M, Sardinha LB, Martins P, Minderico CS, Silva AM. Effects of a 4-month active weight loss phase followed by weight loss maintenance on adaptive thermogenesis in resting energy expenditure in former elite athletes. Eur J Nutr. 2022 Jul 14.