Metabolic slow down is when you’re body goes into a state that you are unable to continue to lose weight, despite being in a caloric deficit and being very active.
…This happens because the body adapts.
The body wants to be at a ‘normal’, at a certain set point. And when you try to change that ‘normal‘, the body puts up a fight and usually wins in the long term…unless you use a clever approach to fat loss.
Your body burns a certain amount of calories per day to stay alive and to operate. When you eat more than it requires (caloric surplus) your energy expenditure will increase, your metabolism will speed up, and you will start to store fat. The degree of faster metabolism and fat storage will differ from person to person.
if you eat less than what your body burns per day, you’ll be eating in a caloric deficit. After a prolonged deficit, your body will increase hunger and slow down your metabolism (reduce the energy burned at rest).
Let’s look at a few terms:
TDEE can be broken up in 5 parts. BMR (basal metabolic rate), REE (resting energy expenditure), NEAT (non-exercise activity thermogenesis), EAT (exercise activity thermogenesis) and TEF (thermic effect of food).
BMR is the amount of calories needed daily just to keep you alive.
REE (resting energy expenditure)/RMR (resting metabolic rate) represents fasted-state energy expenditure at rest at any time of the day, and can range 3–10% higher than BMR due to the residual influence of TEF and physical activity. The greatest contributors to REE, per unit of mass, are the heart and kidneys, each spending approximately 400 kcal/kg/day, and the brain and the liver, at 240 and 200 kcal/kg/day, respectively. These four organs constitute up to 70–80% of REE. However, on a net basis (accounting for the total mass of each tissue in the body), muscle, brain, and liver are the top 3 contributors to overall REE, of which muscle contributes 22%, liver 21% and the brain 22% (1). In contrast, muscle and adipose tissue expend 13 and 4.5 kcal/kg/day, respectively. Even a significant increase of 10kg of lean muscle would only increase REE by ~130 kcal/day. Thus, substantial losses in lean mass can meaningfully impact REE.
NEAT encompasses the energy expenditure of occupation, leisure, basic activities of daily living, and unconscious/spontaneous activity such as fidgeting. NEAT can vary about 15% of TDEE in sedentary individuals and perhaps 50% or more in highly active individuals. The impact of NEAT can be substantial since it can vary by as much as 2000 kcals between individuals of similar size
EAT is the thermogenesis produced from exercise. EAT has been reported to range from 15 to 30% of TDEE.
TEF is the thermogenesis produced from eating, digesting and processing food through the digestive tract.
BMR typically amounts to 60–70% of TDEE, TEF 8-15%, REE 3-10%, EAT 15-30% and NEAT 15-50%.
As a result of a caloric deficit, you will lose weight, and in lean and obese subjects, maintaining a drop of ≥10% of total body weight results in a ~20–25% decrease in TDEE. That’s a lot.
What happens in your body during metabolic slowdown?
Your thyroid is responsible for releasing a hormone, particularly triiodothyronine (T3), which is known to play an important and direct role in regulating metabolic rate.
Eating in a caloric deficit for a prolonged period of time lowers T3.
Lowered T3 levels result in decreased thermogenesis and overall metabolic rate (1)
Testosterone is known for increasing muscle mass, and it also plays a role in burning fat .
A caloric deficit also lowers testosterone.
Keep in mind that fat also lowers testosterone. So in order to increase your natural testosterone levels, you need to lose weight – become lean. But being in a caloric deficit for too long will lower your testosterone levels as well.
Insulin, Leptin & Ghrelin
Insulin and leptin increase satiety while ghrelin increases hunger.
Leptin signals short and long-term energy availability and higher concentrations of leptin are associated with increased satiety and energy expenditure 
Insulin lowers ghrelin. Insulin is high after a meal and returns to baseline after a few hours. Insulin improves satiety.
A caloric deficit lowers both leptin and insulin.
And when insulin is low, ghrelin increases and increases constant sensations of hunger.
Hence, a caloric deficit decreases satiety and increases hunger.
Cortisol is a catabolic hormone that increases the breakdown of tissue in the body, including fat, muscle tissue etc. But as you aren’t consuming enough energy (calories), your body now has to break down its own tissue in order to provide energy for the body. We want our bodies to only break down the fat, while maintaining all our lean muscle.
A caloric deficit increases cortisol, which increases the risk of lean muscle loss. But this only becomes a real problem when we become really lean (<10% body fat), as we then have lots less fats to use for energy.
Uncoupling Proteins (UCPs)
Uncoupling proteins (UCPs) are responsible for something called proton leak. Proton leak increases resting energy expenditure (REE) – which is the energy the body uses during rest. There are two uncoupling proteins of interest, UCP-1 and UCP-3.
A decrease in UCP-1 reduces the thermogenic activity of brown adipose tissue (BAT) (4). So the more UCP-1, the more fat we burn at rest.
A decrease in UCP-3 expression could decrease energy expenditure, and UCP-3 expression has been negatively associated with body mass index and positively associated with metabolic rate during sleep (5).
One of the reasons for this, is that thyroid hormones, such as T3, plays an important role in regulating the activity of proton leak (6). Meaning, a decrease in T3 would lead to a decrease in proton leak. Hence a decrease in UCPs leads to a decrease in metabolic rate and thermogenesis.
Let’s look at how to prevent these negative metabolic changes
Your body induces these changes to increase the possibility of survival, in case of a food scarcity. So your body actually has your best interests in mind – survival. But we don’t want that to happen as we aren’t really in the situation of real-life food scarcity. These changes, however, can’t completely be inhibited during a caloric deficit, but can be minimized…
1) Ensure optimal thyroid health
Metabolic slow is a result of low thyroid hormones and can lead to hypothyroidism. Some people have thyroid problems even if they aren’t in a caloric deficit. You want to ensure that your thyroid is working optimally so that it’s not working slower than it has to. You want it to perform at its best, to be at optimal health, at all times.
All your daily essential minerals and vitamins help the thyroid to work optimally.
It’s been found that vitamin A, B12, C, D, E, iron, copper, zinc, magnesium, manganese and selenium deficiencies negatively affect the thyroid (7, 8, 9, 10, 11, 12, 13, 14). And probably all the rest, but they have not yet been studied. There is a good reason why it’s called essential nutrients. Your body needs them every day, and also requires a certain amount of them each day. So as you can see, deficiencies cause problems.
It’s also been found that eating a low carb diet lowers thyroid hormones compared to a moderate to high carb diet. And when I recommend a high carb diet, it won’t be over 50% of your total daily calories, but rather 40% on training days, and 25-30% on off days.
Two awesome testosterone boosting supplements that will also improve thyroid function are ashwagandha and forskolin.
2) Small deficit
In order to lose weight, you need to be in a caloric deficit. Usually, that would be a daily 500 calorie deficit (of maintenance) in order to lose one pound of fat a week. Less than 500 might result in slower fat loss and more than 500 might result in faster fat loss.
However, the bigger the deficit, the faster metabolic slow down will take place. You will also feel cranky, sluggish, tired and cold due to your body that’s trying to save its energy for survival.
Keep the deficit small (500 calories) and just be patient with fat loss. This small deficit will result in little to no metabolic slowdown.
So I advise being in a 500 calorie deficit each day in order to lose weight healthily.
3) Higher protein diet
Protein increases thermogenesis (the body’s ability to produce heat) and gives the greatest satiety of all the macronutrients. Protein is very important to maintain lean muscle mass during a caloric deficit. It is also involved in the production of neurotransmitters, hormones, red and white blood cells and much more.
It’s advised to eat 2.2-3.1g/kg/BW of protein when you are losing weight (15). If you are very active, consider eating at the high end of that recommendation. But again, everyone is different and needs different amounts of protein, so it’s important that you experiment and find out what is best for you. More on protein and fat loss here…
4) Weight training
Everyone should exercise in some way, as being active is very important for your health. When you do weight training, you burn a certain amount of calories, and afterwards, it increases your REE, (meaning you burn more calories at rest). Weight training is most important for maintaining your muscle while being in a caloric deficit. Weights produce that anabolic stimulus and “reason” for your body to keep your muscle. Muscle is very metabolically expensive to keep. So in order to keep your muscle, you have to lift some weights.
5) Decrease your caloric deficit in decrements
Only a small portion of the population of men really want to get super lean, and that’s where it can get tricky. Getting very lean increases the risk of metabolic slowdown, as well as the risk of lean muscle loss and lack of energy.
So if you do want to get super lean then the trick is to decrease your calories in small decrements.
While you are in your 500 calorie deficit, and weight loss stops, reduce your calories by another 100 to get fat loss going again. And repeat this process until you achieve your goal. Don’t just jump to low calories and get metabolic slowdown, but rather eat more while you’re still able to lose fat. If you start off with very low calories in the first place, it will be even harder to deduct more calories later.
Remember, as you lose weight, your BMI changes, and so does your maintenance calories.
It’s not needed to eat less if you are already losing weight at a certain amount of calories. Only if you get stuck, then reduce your calories a bit more.
A refeed is very important in order to increase your daily calories a little above maintenance to increase metabolic rate. A refeed will then give the thyroid the idea that you aren’t really in a food scarcity and that there is no need for reducing thyroid hormone production.
Refeeds are usually incorporated once or twice a week, depending on the body fat percentage of the individual. The more fat an individual has, the less it’s necessary to refeed.
So a refeed is very important to increase REE.
Refeed days are done by keeping protein and fat the same as on the other days, but just increasing the carbohydrate content till you’re slightly over maintenance calories, as fat is unable to increase REE, but only carbs (16).
For example, if your calories are 2300 on training days, in order to lose weight, then your macronutrients will look as follows – 35% total calories protein (201g), 25% fats (64g) and 40% carbs (230g).
For a refeed on a training day, your calories will be 2800 and will look as follows – 201g protein, 64g fats and 355g carbohydrates. So you would push up your carbs, in this case, by 125g for that one day in order to eat maintenance calories.
Refeed days would best be done on days when training a big muscle group such as back or legs.
7) Calorie cycling
Calorie cycling is kind of like refeeding.
It works like this. You eat in a deficit some days, and maintenance or small surplus on other days. On training days, you burn more calories than on rest days. So it would be better to be on a deficit on training days, and then on rest days, eat maintenance calories to give your body a rest from being under the stress of a caloric deficit.
Let’s say you train 5 days a week. So during the week (workout days), you’ll be burning 2800 calories, so you’ll be eating 2300 calories to be in a deficit. Then on the weekend, you’ll eat maintenance calories of 2300. People who do calorie cycling experience far less metabolic slow down than people who don’t (17).
Calorie cycling can also be done when bulking lean, in order to build only muscle and gain no fat.
More on calorie cycling here…
I hope you enjoyed reading this article and have learned something new. If you want a complete training program with dietary guidelines on how to get ripped and build a symmetric muscular physique of your dreams, get my Victorious Shredding Program, which is a comprehensive guide on how to achieve your cutting goals.
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