Ever wonder why it gets harder and harder to lose weight the longer you diet?
Or why do you see people eating 1200 calories and NOT losing weight?
So what is metabolic adaptation?
For us to be able to see weight loss, the body must be in a ‘negative energy balance’ - meaning we must burn more energy than we consume (i.e. calories). There are a lot of camps that like to argue this, but research continues to show that a calorie deficit is necessary to see the scale drop.
So why can’t we just eat 1000 calories each day and lose weight until the end of time? Well, these bodies of ours were designed for two things: survival and procreation. What this means is that when we try to ‘starve’ our bodies to get extremely lean, the body itself sees this as a threat to our well-being and this where metabolic adaptation comes into play.
The body has certain defense and safety mechanisms in place to make sure we don’t diet ourselves to death. What this means for us is that when we try to create a larger and larger calorie deficit with diet and exercise, the body works to conserve energy as much as possible in other areas to ensure it can hold onto enough body-fat to feel safe and protect itself. So what areas does the body adjust to stall out our weight loss?
There are a few main hormones that play roles in the regulation of our metabolism, body-composition, and our body’s ability to burn fat. These each get impacted by a caloric deficit and weight loss in certain ways that can start to slow down progress. These are by no means the only hormones that get impacted, but these are some of the most notable ones:
Although everything we are talking about today is in essence a ‘metabolic response’ - these areas we are going to discuss next are the main contributors to caloric burn in a day. They each get impacted negatively as well with a calorie deficit.
Many people will turn to exercise to work to increase their energy balance and essentially try to create their calorie deficit with more cardio, more ‘active calories’ on their Apple Watch, or ‘burn the fat off.’ The body’s response to increased levels of exercise is definitely something that research seems to be a bit unclear about still, but from what we can tell, females tend to see more adaptation than men do.
We will focus a bit more on the ladies in this section, because men - you have it a bit easier. The male body and hormones do not adapt as easily or as quickly as the female body does, and the main reason is because the female body is the one which has to build and carry a human during pregnancy, and in turn, the female body’s defense mechanisms are a bit more sensitive and strong.
One of the biggest misconceptions that females have about fat loss is that the more movement we do, the more calories we burn - and in turn, the more fat we burn. This is simply not true because the female metabolism in particular is reactive, not additive. There was one study that demonstrated this perfectly, which compared total daily energy expenditure and total minutes of exercise per week. What you may expect is that as energy burn increases, total daily energy expenditure would increase, but the metabolism doesn’t work like that. Metabolic adaptation happens.
As exercise calorie burn increased, the total daily energy expenditure actually pulled back and went down to compensate for the extra movement to drop overall daily calorie burn down (source). This goes back to our basal metabolic rate that manages energy towards our organ function and systems within the body. This is where energy gets conserved! Instead of burning more calories, our body takes energy from our systems to bring energy balance back and close the gap. It will pull energy from our immune system meaning we get sick more often or show lower white blood cell counts. It pulls energy from digestion meaning we may end up with bloating, constipation, or other digestive problems. It pulls energy from our reproductive system and we start to see irregular periods or no sex drive. It lowers brain function and you’ll start to notice fatigue or brain fog more commonly.
So instead of burning MORE calories, our body really just takes energy and conserves it in other places, making you feel run down, crummy, and stalled out with weight loss because like we said, the body really is designed to survive - it is not concerned about aesthetics.
Metabolic adaptation sounds like kind of a downer, right?? We get it, we know you have goals and want to lose that weight, but depending on how long you’ve been trying, your body may have other plans. If you have been in a long-term calorie deficit, or you’ve stalled out with weight loss, some great ‘markers’ we look for to let our body tell us it needs a break, and to perhaps start eating a bit more or exercising a bit less are the following:
As we always tell our clients, listen to your body talk so you don’t have to hear it scream! Our bodies are great guides for us to know when they need a bit more support, and when we can push them a bit harder as long as we’re willing to listen.
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