Staggering 80% of people who lost a significant amount of weight gain it back within the next 5 years. One of the reasons behind it is the metabolic adaptations of the body, often referred to as “metabolic slowdown”. In this article I explain everything there is to know it and what you can to do avoid it.
The metabolic slowdown is the effect of lowered metabolic rate after significant weight loss or restricted calorie intake. After weight loss occurs, the resting metabolic rate goes 15–40% below its predicted value, which makes it extremely hard to maintain the results.
We can estimate metabolism to some degree using BMR equations based on age, height, and weight. But metabolic slowdown can lower your calorie burn way below its estimated value.
What Causes Metabolic Slowdown?
Have you ever thought how come when you eat less food you can still gain weight? Is this even possible? Our metabolism is extremely complex and dynamic. It can fluctuate like a stock market.
And frankly, it’s not a mystery anymore what is actually going on behind the scenes. And this allows us to maximize the loss of body fat while minimizing the loss of lean body mass.
With drastic weight loss and severe calorie restriction, our body starts to implement several changes to protect us from eating ourselves.
As the result, we don’t use as much energy as we should. Here are some of the examples:
- Decreased thermogenic effect of food
The more food you eat, the more you need the energy to extract and process nutrients to be used for the body. Because we eat less food, we gonna need less energy to digest and break down what we eat.
- Decreased basal metabolic rate
The heavier we are, the more calories we need. Calories are burned for things like blood flow, breathing, protein synthesis, and cognitive tasks. So now imagine if you lose 50-pounds of body weight, that immediately lowers the demand for energy.
- Decreased lean body mass
Unless you’re a gym rat, whenever you lose weight it’s gonna be the combination of fat and muscle. Of course, we want to keep as much lean mass as possible because it is the main driver behind the high metabolic rate.
With more muscle mass, you burn more calories. So one of the silver bullets for avoiding metabolic slowdown is to do strength training.
- Endocrine changes
After the hypocaloric diet, there are several changes happening in the endocrine system. This includes lowering leptin, increasing appetite, lowering testosterone, and thyroid hormones.
Are you wondering how those changes can affect your weight loss goals? All those adaptations accumulated together will cause our body to use much less energy than normal (source).
Here is the kicker. Based on the mathematical equations we can more or less calculate our basal metabolic rate. To illustrate you how metabolic slowdown works I will use a Mifflin equation and 40-year-old male as a model.
Here is the example of the Mifflin metabolic rate equation.
RMR = 10 x (weight in kilograms) + 6.25 x (height in centimetres) – 5 (age in years) + 5
RMR = 10 x (weight in kilograms) + 6.25 x (height in centimetres) – 5 (age in years) + 161
Imagine you have two guys of the same age and the same height but different body weights.
One is 100 kg (220 pounds) and another one is 50 kg (110 pounds).
According to the BMR equation, you can see that there is around a 500 calorie difference in daily energy expenditure. The guy who weighs 100 kg is close to 2000 calories, where the guy with 50 kg is around 1400.
The problem with metabolic slowdown is that when the guy who weighs 100 kg drops down to 50 kg, his BMR will be 15-40% lower than the guy who is already at his 50 kg. The drop will exceed the estimated BMR as adaptive thermogenesis (source).
What happens after that we all know. After being so long in the calorie deficit and dieting we eat as normal. But because now we burn fewer calories than before, we gain the weight back (source).
To some degree, this process also applies to radical calorie restriction. If we suddenly lower calorie intake, our body will reduce total daily energy expenditure and after going back to normal eating, we may gain the weight back.
Related article: Why am I gaining weight in a calorie deficit?
How To Avoid Metabolic Slowdown
Generally, we cannot avoid metabolic slowdown after weight loss. What we can do to minimize the effect is by adding a sufficient amount of resistance training and protein intake.
This will keep the resting metabolic rate high. In fact, studies show that by adding resistance training and protein you can positively exceed your metabolic rate (source).
It will stimulate muscle protein synthesis by building muscle mass. And as we know, the more lean mass we have, the more calories we gonna burn at rest (source).
And you don’t need to spend days in the gym to get good results. Your goal is to hit all the major muscle groups and add more volume as you progress. This is called progressive overload. Over time you add more weight, sets, or reps. So you don’t do the same exercise with the same amount of weight or reps all year round.
Best exercises for progressive overload:
- Bench press / push up
- Kettlebell swings
High protein will not only provide you satiety but also the building blocks for the new muscle. So by prioritizing protein in your diet, you will make sure that the weight is coming off from fat, not from the muscle.
Current recommendations for protein intakes during weight loss are around 1.6-2.4 g protein per kilogram of body weight per day.
At the end of the day, it doesn’t matter where you getting your proteins from. However, the best protein sources will have most if not all of the amino acids. That include:
- Protein shakes
Metabolic slowdown will happen regardless if you’re active or not. But you can dramatically improve your results and keep your metabolism as high as possible simply by eating more proteins and adding some resistance training to your program.