Metabolic adaptation is the phrase used to describe the efficiency with which your body switches between fuel sources, and the processes which can change as a downstream result of this.
Thinking back to when we used to live in caves and hunt for our food, metabolic adaptation was the reason we didn’t starve to death after a day with no food. Our bodies tapped into their stores when they ran out of fuel from the food we’d eaten, and at the same time, slowed down the speed at which our body worked in order to conserve as much as possible for the future.
When we take this information and apply it to our lives today, and how we lose or gain weight, we can immediately see why starving ourselves isn’t the answer.
Almost regardless of the amount of exercise we do, our biggest use of energy is by our metabolism (the basic workings of our body). If we don’t have enough food going in, our body will reduce the amount of energy it spends, and turn the focus to saving as much as possible.
This also explains why weight loss stops after a while even if you go about creating an energy deficit in the right way. After a couple of weeks, your body adapts to the reduced energy intake and finds a way to maintain itself at the new intake. Most people then decide to reduce their intake further, which usually results in a bit more weight loss, followed by their body adjusting to the new intake and finding a way to maintain itself at this new intake.
Clearly, this can’t go on forever. At some point, we are eating so little that our health suffers; not to mention that eating too little long-term guarantees we will eventually crack and find ourselves 3/4 of the way through a packet of hobnobs before we’ve even realised what we’re doing! The overeating end of the yo-yo diet then encourages our body to store as much fat as possible during the huge influx of energy, in order to prepare for the next phase of under eating. Fixing this is where reverse dieting comes in. I wrote about this several weeks ago. If you’d like to read more about it, please send me an email and I will send you the piece I wrote.
So, what is the right way to lose weight? We need to eat at a small deficit, consistently, and we need to keep telling our body that we need to prioritise maintenance (and growth) of energy-hungry muscle tissue, by doing the right sort of exercise to send this signal and by eating a decent amount of protein to allow the muscle to be built and maintained. Then, we need to add in the odd day or two where we eat at a small excess, and finally we need to allow a bit of time, patience and trust.