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Most of us rarely consider our metabolism unless we are concerned about our body weight. Yet, metabolism is the foundation for all body functions and is unique to each individual. Most people approach weight loss through crash dieting or by altering their daily calories or caloric intake through diet, usually through a calorie deficit, or increasing their physical activity levels. However, this strategy often interferes with normal, healthy metabolic processes and sometimes results in a survival mechanism called metabolic adaptation. Here, we dig into metabolic adaptation and how you can fix it when your metabolism has decreased.
Metabolism is the chemical process by which the body uses energy. There are three primary ways we use energy:
- To provide fuel for our cells to keep our bodies alive and functional
- To help us digest food that gives us more energy for use or storage
- To allow us to move
The majority of energy expenditure goes to fuel our cells. We use this energy to regulate vital functions that maintain homeostasis like body temperature, heart rate, breathing, and cellular growth and repair.
Our bodies need a minimum number of calories per day to sustain our energy intake or requirements at rest to perform these functions. This minimum number of calories per day forms our basal metabolic rate (BMR) and accounts for 60-70% of our energy requirements and energy expenditure.
Age, sex, muscle mass, weight, and genetics influence your BMR. Certain conditions can also affect your metabolic speed. For example, hypothyroidism and Cushing's syndrome can cause a slow metabolism, whereas hyperthyroidism speeds it up.
Metabolic adaptation is the body's survival mechanism to ensure we have enough energy to perform essential functions. Also called adaptive thermogenesis, this physiological process helps us survive in times of food scarcity.
When we do not have enough energy from the food we eat, our bodies use up as little energy as possible and store anything extra as fat for later use. When we frequently experience food scarcity, our basal metabolic rate can be reset through metabolic adaptation.
Today, food scarcity does not come from starvation for most people in the United States but rather from dieting and purposeful caloric restriction for weight loss and weight loss goals. However, metabolic adaptation can delay weight loss progression because of how our bodies respond to food scarcity.
When most people start a diet, they lose a few pounds initially due to a reduced food intake of their daily calories. At some point, their body weight stays the same even though their caloric intake is stable. This plateau occurs because the body adjusts the metabolism to a new basal metabolic rate. The BMR is lower because:
- Our energy requirements to digest food decrease because we are eating less, and
- Energy requirements are lower to sustain basic body functions because the weight has decreased.
Once a person reaches a weight loss plateau, it is hard to progress without further restricting calorie intake or increasing purposeful exercise. Calorie restriction can make you feel run down and hungry, putting your body into survival mode, where any extra energy is stored as fat. Essentially, your body uses metabolic adaptation to prevent you from losing too much weight.
So, while severely restricting calories is often recommended for weight loss, it is usually not a long-term solution for maintaining a healthy metabolic adaptation.
Metabolic damage occurs when the body has been in starvation mode for too long, and the metabolism shifts its focus to energy storage and conversation. This mechanism was essential when we were hunter-gatherers, but today it is often the driving force behind lifelong weight struggles.
The primary cause of metabolic damage in modern-day humans is on-and-off dieting. It is commonly seen in people who try different fad diets. As a result, the metabolism gets confused and does whatever it can to ensure survival.
Therefore, people with metabolic damage often have a strained relationship with food, and feel hungry, irritable, or tired leading to either weight gain, a slower rate of weight loss or weight loss resistance. Other related issues may also include depression, anxiety, and gastrointestinal problems such as diarrhea and bloating.
If you have weight control issues and have tried dieting in the past, you may have some disturbances in your metabolism. However, other causes may undoubtedly contribute to weight problems, including hormone imbalance.
There are several steps you can take to fix metabolic adaptation. The first, and perhaps most important, is to see your doctor to ensure your symptoms are not related to another condition such as hypothyroidism. If so, you will likely need to do a full panel thyroid test to rule out any potential case of thyroid dysfunction.
Secondly, people often benefit from taking a diet break to reset their systems. Of course, this is not when you want to consume more calories than you need, as that also contributes to metabolic adaption. Rather, you will want to focus on certain eating habits, such as:
- Following a high protein diet, as protein keeps your muscles strong and helps you feel full
- Eating a variety of whole foods
- Feeding your healthy intestinal gut flora with fiber
- Limiting your processed food intake, and
- Eating at regular intervals so your body knows when to expect more food.
By focusing on whole foods and protein, your body will shift more energy toward digestion, which can help help your energy metabolism swing back in the right direction.
Regular physical activity is also important. Strength and resistance training exercises may be beneficial for keeping body fat from accumulating and fat-free mass high.
Another important component of fixing metabolic adaption is stress reduction. One of the best ways to reduce stress is to get plenty of sleep. However, alleviating stress in other areas of your life is also highly beneficial for your overall health.
Weight gain and weight loss resistance are one of the most frustrating symptoms of hypothyroidism. Unfortuantely, metabolic adaptation is also something the majority of our patients struggle with. If you notice issues such as weight loss resistance or weight gain, it is worth getting a complete thyroid bloos test kit. Your at-home thyroid test kit contains everything you need to collect and test your Thyroid Stimulating Hormone (TSH), Free T4, Free T3, and Thyroid Peroxidase (TPO) antibodies. You'll also have the option to add on reverse T3 and vitamin D tests.
If a thyroid condition is noted in your results, a Paloma Health thyroid specialist can work with you to address both your thyroid dysfunction and metabolic adaptation through medication, lifestyle and nutritional changes.