Why do people Re-gain the weight After their WeightLoss?
In my previous blogs, I had explained why the body defends against weight loss and favors weight regain after weight loss—and why it makes sense from an evolutionary standpoint.
This “self-defense system,” as I referred to it, utilizes a three-pronged attack to defend your body against perceived famine:
1. It slows metabolic rate through metabolic adaptation.
2. It activates genes that favor weight regain.
3. It causes changes to your biology that make it more difficult to lose weight in the future.
Now it’s time to dive deep into the biology of this self-defense system.
What is “Metabolism”?
I use the term “metabolism” a lot here in these series, and it sure sounds fancy. But what exactly is metabolism?
The dictionary defines metabolism as “the chemical changes in living cells by which energy is provided for vital processes and activities and new material is assimilated.”
On a basic level, it’s the process of extracting energy from the food you eat and producing energy to power your cell’s biological processes.
The molecules in food, like proteins (amino acids), Carbs (sugars), fats, and others, all contain energy that can be extracted through the process of metabolism.
The end product of macronutrient metabolism is the molecule adenosine triphosphate (ATP) as well as water and carbon dioxide.
As discussed in the previous blog, ATP is essentially the energy currency of the cell. The process of hydrolyzing ATP is used to drive many cellular reactions.
If we eat an excessive amount of energy compared to the ATP we use (burn), then we store this energy in FAT Cells -aka-adipose tissue (and, to a lesser capacity, lean mass (Muscles), and glycogen(Liver).
If we eat fewer calories than required to produce the ATP needed to run these chemical processes, then that energy must be released from storage in the form of adipose tissue—body fat and, to a lesser extent, lean body mass (LBM) and glycogen.
When I refer to someone who has a “fast metabolism,” I mean that their body is inefficient at the production and usage of ATP on a cellular level and that they end up wasting a lot of potential energy.
These people are the “Ferraris Cars” of metabolism, and they burn through a lot of energy. In fact, I am a kind of that person whose body type (Ectomorph) was tall and lean from a very young age. with proper nutrition and training, I rebuilt that frame to an athletic level.
If I refer to someone as having a slow metabolism, then that person is likely very efficient at ATP production and utilization. (Endomorph)
Someone with an efficient (slow) metabolism can waste less ATP and produce more ATP from less energy intake, meaning fat storage is easier for this person. they are efficient with energy.
How much energy goes to “waste” is in large part determined by the level of thermogenesis occurring in the body. Thermogenesis refers to the production of heat through dissipation (aka “wasting”) of energy (aka calories).
On a cellular level, much of this occurs in the mitochondria through the activity of uncoupling proteins. These proteins cause “uncoupling” of the mitochondrial membrane, which makes ATP production less efficient, and the wasted energy is given off as heat.
This process is complicated, but if you really want to nerd out about it, the production of ATP is powered by an enzyme called ATP synthase, which is located in the inner mitochondrial membrane and catalyzes the production of ATP from ADP + Phosphate ion.
To drive this reaction, a hydrogen ion gradient is created by pumping out hydrogen ions from the inner mitochondrial membrane.
This hydrogen ion gradient then drives ATP synthase. Uncoupling proteins make this process inefficient by making the membrane “leaky,” so that the hydrogen ion gradient is dissipated, less ATP is produced, and the dissipated energy is given off as heat.
Thus, increased thermogenesis means more calories are “burned.” When I talk about people who have “fast” metabolisms and “burn” through more calories, this is a big part of what we’re referring to on a cellular level.
This may all seem a bit complicated, but it’s the crux of the age-old idea of “calories in versus calories out” or, as I have referred to previously, energy balance. This is a broad overview, but it’s important to understand generally what I am referring to when I say “metabolism,” “metabolic rate,” and why “efficient” typically means “slow” and “inefficient” typically means “fast.”
The Metabolic Consequence of Dieting
Dieting activates your body’s self-defense system. However, this isn’t an “on” or “off” switch—it’s a proportionate response. The more severe the energy deficit and the longer it’s imposed, the greater the signal to activate this system.
If a person who doesn’t typically diet goes on a 2-week shortcut to lose a few Kilos. it’s not nearly the same problem as someone trying for the 20th time in a series of yo-yo diets to drop 10 or more kilos.
Three main factors will determine how strong the activation of the self-defense system will be:
1. The severity of the energy deficit (calorie deficit).
2. How long the calorie deficit is imposed.
3. How frequently the calorie deficits are imposed
It’s important to clarify that not all diets have the same impact on this system. I don’t want you to be terrified of trying to lose weight or to simply assume that any weight loss attempt is hopeless.
They aren’t hopeless, but they need to be planned correctly and executed correctly, or there’s a high likelihood you’ll be no better off than when you started—or, in many cases, you’ll be worse off than when you started.
As I mentioned, the first prong of the body’s self-defense system is a metabolic adaptation to reduce your total daily energy expenditure.
What’s interesting is that the drop in metabolic rate is almost always greater than you would predict based on the person’s LBM (lean body mass) and activity level.
We can predict with relative accuracy what someone’s metabolic rate should be based on different equations that calculate the basal metabolic rate (BMR).
However, in people who diet, especially those who have dieted for long periods, we find that their BMR is much lower than it should be. It’s as if the body overreacts to dieting.*1
Many people find it pretty easy to lose initially during a diet when their metabolic rate is still normal (assuming they haven’t already engaged in a lot of yo-yo dieting that slowed their metabolic rate) but over time, your metabolic rate slows to adapt to the calorie deficit.
It’s really a catch-all for various metabolic changes in the body that work to slow down your total daily energy expenditure (TDEE), and nearly every component of your TDEE is affected. Let’s discuss the major factors of metabolic adaptation.
BMR (Basal Metabolic Rate)
During caloric restriction, the body’s basal metabolic rate adapts to the decrease in energy intake by dropping energy expenditure significantly.
Now, BMR encompasses many metabolic processes, so referring to it as a single aspect of metabolic adaptation is a bit misleading. However, for the sake of not turning this into a theory, we’ll keep it that way.
Most available research suggests that the reduction in BMR during dieting is about a 15% decline below predicted on average—but can be far greater in extreme cases.*2 *3 *4 Much of this decline in BMR is due to the reduction in weight and lean mass from dieting.
Since lean mass (and, to a much lesser extent, fat mass) are metabolically active tissues, you’ll have a reduction in BMR as you lose weight just due to less overall tissue and less energy needed to carry around the reduced body mass.
This change in body mass, however, is not nearly enough to account for the total decrease in energy expenditure.*5 It’s likely that the level of adaptation is proportionate to the level and duration of the restriction.
As I mentioned earlier in the series participants from the TV show The Biggest Loser demonstrated over a 20% metabolic adaptation that persisted even six years after the show ended.*6
NEAT (Non-Exercise Activity Thermogenesis)
NEAT is probably the component of your TDEE that has the biggest relative adaptation during caloric restriction. Indeed, research has shown NEAT to be reduced by a massive 400 calories per day in people who lost at least 10% of their body weight.*7
While some people dismiss the changes in NEAT, claiming that it’s modifiable and that people can make up for it by simply “moving more,” this isn’t the case.
True NEAT is a non-voluntary movement such as fidgeting, postural, and walking movement. If you have to think about fidgeting or pacing more, then it’s no longer truly NEAT.
Some people think that they can make themselves fidget more, but that requires conscious effort, which can likely take away from other conscious tasks you’re trying to do.
For example, if you’re consciously thinking about needing to fidget so you can burn more calories, you’ll probably have a harder time effectively doing jobs that require higher functioning.
There are a few ways to “cheat,” such as getting a standing desk if you’re confined to a desk. However, by expending more energy standing during the day, you may have less energy for other tasks, or you may move less when performing them or become more efficient with movement during those tasks.
I am not trying to make it seem hopeless, but I also don’t want you to think there are “hacks” or “tricks” to help you burn more calories without thinking about it.
TEF (Thermic Effect of Food)
TEF as a percentage of TDEE seems to be largely unaffected by dieting. However, since you’re eating less food, the absolute amount of calories burned from TEF will be lower while the relative rate may be unchanged.*8
Keep in mind that TEF is a very small proportion of your daily calorie output, so even if it’s unchanged, it doesn’t seem to have a huge impact one way or the other.
EA (Exercise Activity)
Dieting reduces the amount of energy you expend during exercise.*9 Ever hear someone say something to the effect of, “I don’t understand why I can’t lose weight when the cardio machine says I’m burning 1000 calories!”
The hard truth is, that you’re most likely burning far less than that during exercise. Just think about times in your life when you’ve been overfeeding for long periods.
You might have broken a sweat just standing up and moving around, whereas when you’re dieting, you find yourself constantly cold. This is another example of reduced thermogenesis.
In fact, studies examining people who add cardiovascular exercise to their normal daily routine show only small, short-term reductions in body weight.*10 *11
I am not saying don’t exercise, because exercise has many other awesome health benefits besides weight loss. I am also not saying that exercise won’t help you lose weight. I am just saying that it’s only going to give you an initial boost, and then it will become your new “maintenance” level.
To be continued …
1 “Metabolic adaptation following massive weight loss is … – NCBI – NIH.” 19 Sep. 2014, https://www. ncbi.nlm.nih.gov/pmc/articles/PMC4236233/. Accessed 10 Sep. 2018.
2 (2014, February 27). Metabolic adaptation to weight loss: implications for the athlete. Retrieved January 3, 2018, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943438/
3(2016, May 2). Persistent metabolic adaptation 6 years after “The Biggest Loser …. Retrieved September 6, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/27136388
4 (2013, February 14). Natural bodybuilding competition preparation and recovery: a … – NCBI. Retrieved September 6, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/23412685
5 Metabolic slowing with massive weight loss despite preservation of fat …. Retrieved January 3, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/22535969
6 (n.d.). Persistent metabolic adaptation 6 years after “The Biggest Loser …. Retrieved September 6, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/27136388
7 Long-term persistence of adaptive thermogenesis in … – NCBI – NIH. Retrieved January 3, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/18842775
8 Effect of weight reduction on resting energy expenditure, substrate …. Retrieved January 3, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/1570799
9 Greater than predicted decrease in energy expenditure during … – NCBI. Retrieved January 3, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/12617720
10 “The impact of exercise and diet restriction on daily energy expenditure..” https://www.ncbi.nlm.nih. gov/pubmed/2017606. Accessed 10 Sep. 2018.
11 “[Adaptation of food ingestion to energy expenditure]. – NCBI.” https://www.ncbi.nlm.nih.gov/ pubmed/3550978. Accessed 10 Sep. 2018.
