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"My metabolism is too slow!" It's a common complaint of many hypothyroid patients. When you're hypothyroid, your thyroid doesn't produce enough thyroid hormone for your body's needs. A lack of thyroid hormone in your bloodstream slows down virtually every system in your body, including your metabolism. And a sluggish metabolism can leave you tired, brain-fogged, and gaining weight. It can also make it hard to lose unwanted pounds — even with a healthy diet and exercise.
How does your metabolism function? And what is the relationship between hypothyroidism – an underactive thyroid gland – and your metabolism? If you're hypothyroid and having difficulty losing weight, how can you boost your metabolism to make it easier? Ahead, we explore these essential questions about hypothyroidism and metabolism.
You'll often hear the term "metabolism" in terms of someone's tendency to lose weight, maintain their weight, or gain weight—and the speed of that weight loss or weight gain.
Metabolism is much more than a weight loss speedometer, however. Metabolism refers to the many complex chemical processes in your body to convert your food into energy. The energy produced by the metabolic process powers everything, from breathing and digestion to organs like the heart and brain. But simply put, the difference between a slow and fast metabolism is about how many calories you typically burn, at rest, when you're eating, and when you're physically active.
Your endocrine system and its hormones oversee the metabolic process. The thyroid has earned the unofficial title of "master gland of metabolism" because thyroid hormones set the pace, determining the speed of all the chemical reactions.
How does it all work? After you eat, enzymes help change the proteins you eat into amino acids, fats into fatty acids, and carbohydrates into glucose (sugar). Then, insulin–the endocrine hormone produced by your pancreas–comes into play, helping your body convert carbohydrates into glucose.
Once converted, your bloodstream absorbs amino acids, fatty acids, and glucose. They travel to your cells, where more enzymes help direct the release of energy. Your body uses some energy immediately; the remainder is stored for later use in tissues such as the liver, muscles, and body fat.
Some people can easily maintain a healthy weight. Others find it difficult to lose weight or gain weight on lower-calorie diets. What's going on? Each of us has a unique metabolic rate, and it's based on three variables:
- Basal Metabolic Rate (BMR) / Resting Metabolic Rate (RMR), which makes up around 60% of your metabolism
- Active Energy Expenditure (AEE), which makes up around 25% of your metabolism
- Thermic Effect of Food (TEE), which makes up around 15% of your metabolism
1. Basal/Resting Metabolic Rate (BMR/RMR)
The Basal/Resting Metabolic Rate (BMR/RMR) is how you burn energy/calories to support your body's essential functions, including breathing, blood circulation, and organ function. Your BMR/RMR reflects the speed of these reactions in your body and is determined by various factors, including:
- Age – The metabolism tends to slow as we age.
- Body composition – Muscle requires more energy than fat to maintain and speeds up metabolism. Conversely, a higher percentage of body fat is associated with a slower metabolism.
- Diet and nutritional status – A functional metabolic process requires amino acids, vitamins, and minerals from nutritious food.
- Underlying disorders that affect metabolism – Endocrine diseases such as hypothyroidism, diabetes, adrenal fatigue, and other conditions like enzyme deficiencies, inflammation, gastrointestinal/digestive problems, and nutritional deficiencies can all slow metabolism.
2. Activity Energy Expenditure (AEE)
Your Active Energy Expenditure (AEE) depends on two types of activity: your planned exercise and workouts and your Non-Exercise Activity Thermogenesis, known as NEAT. NEAT describes the reflexive, subconscious, or involuntary movements you make throughout the day, i.e., fidgeting, jiggling your foot, walking around, and standing.
3. Thermic Effect of Food (TEF)
The thermic effect of food (TEF) is the energy required to break down food and convert it into energy. Different types of foods and when you eat them all play a role.
Carbohydrates and fats require around 5 to 15% of their calories to process, and protein requires about 20 to 30% of their calories.
Nutritious food – compared to processed food and junk food – provides the nutrients needed to support a faster, more functional metabolism.
Food eaten earlier in the day tends to have a higher thermic effect than food consumed late or at nighttime.
Note: Being well hydrated is also necessary for food to have a maximum thermic effect.
Thyroid hormone also helps regulate both storage and burning of energy, two critical components of metabolism. Research shows that hypothyroidism is associated with a slower metabolism. Specifically, hypothyroidism reduces BMR/RMR, causes weight gain, and makes you less effective at fat-burning.
Whether undiagnosed or not optimally treated, people with overt or subclinical hypothyroidism tend to have a lower BMR/RMR and a higher body mass index (BMI) and waist circumference than people with normal thyroid function.
Thyroid hormones also affect how your body handles glucose. Even mild hypothyroidism is associated with an increased risk of insulin resistance, weight gain, and obesity.
Hashimoto's disease is an autoimmune condition that is the leading cause of many cases of hypothyroidism in the U.S. Hashimoto's is also associated with increased inflammation, a contributing factor to a slow metabolism.
Unfortunately, many Americans with Hashimoto's disease and hypothyroidism are undiagnosed. If you have a slow metabolism, a sensible first step is determining whether you have symptoms of Hashimoto's thyroiditis and hypothyroidism. In addition to weight challenges, some common symptoms include:
- Cold intolerance
- Dry skin
- Weight gain
- Puffy face and hands
- Muscle weakness
- Elevated blood cholesterol level
- Muscle aches, tenderness, and stiffness
- Joint pain, stiffness, or swelling
- Heavy or irregular menstrual periods
- Thinning hair
- Slowed heart rate
- Impaired memory
- Enlarged thyroid gland (goiter)
Whether you're not yet diagnosed with hypothyroidism or need to optimize your current treatment, starting with a complete thyroid blood test panel is always helpful. Some doctors only look at the Thyroid Stimulating Hormone (TSH). Still, it's vital to measure Free T4, Free T3, and Thyroid Peroxidase (TPO) Antibodies to understand the whole picture. A thorough evaluation can determine how your thyroid is functioning and whether it may be impacting your metabolism.
One of the most important ways to help your BMR/RMR and speed up a sluggish metabolism is to optimize your thyroid function. If you're hypothyroid, you should work with a knowledgeable practitioner to get treatment with safe and effective thyroid medication.
There's good news! For some patients, thyroid treatment levels the metabolic playing field. Once the thyroid treatment is optimized, healthy diet and exercise programs that didn't work before can finally show actual results!
Even with thyroid hormone treatment, some people with hypothyroidism still struggle with a slower metabolism. While you can't change your genetics or age, you can help boost your metabolism by focusing on the controllable aspects of metabolism. Here are some recommendations.
Increase your activity and build muscle
Your Active Energy Expenditure is entirely within your control, and the solution is simple: GET MOVING! The more planned exercise and activity you build into each day, the higher your metabolism.
Also, make sure that you incorporate some muscle-building and weight-bearing activities to help increase your BMR/RMR. Building muscle with strength training can help you burn more calories each day – even at rest – because muscle is more metabolically active than fat.
Give your diet a metabolic makeover
Focus on whole foods (not processed), and choose organic and hormone-free options whenever possible.
Avoid fried foods, fatty foods, foods with refined sugars, and processed foods. While these foods are tasty or tempting, they do not require much energy to metabolize, resulting in fewer calories burned and slowing down your metabolism.
It's also helpful to include more protein in your diet with every meal. Protein has a higher thermic effect, and your metabolism has to work harder to break down protein. Make sure you're getting at least 1 gram of protein per pound of body weight to help boost your metabolism.
Also, aim to get 25 grams of fiber per day from foods and supplements. Digesting, processing, and eliminating fiber requires energy, and increasing fiber intake can help boost metabolism. As a bonus, it also helps aid in elimination.
You can also get an extra short-term boost to your metabolism by incorporating some metabolism-enhancing foods and drinks like coffee, teas, and spicy foods. And always make sure you are well-hydrated throughout the day.
Avoid crash diets
Avoid going on a crash diet or following a very low-calorie diet. Cutting too many calories can negatively affect your thyroid and put your body into starvation mode. You'll absorb more calories from the same foods, burn fewer calories for energy, and feel hungry and tempted to binge. This cycle can lead to further weight gain and difficulty losing weight, putting you on the cycle of yo-yo dieting that's hard to escape.
Get enough quality sleep
Sleep is a meaningful way to help boost your metabolism. Growing research suggests that low quality or too little sleep can decrease leptin, the satiety hormone, and raise ghrelin levels, the hunger hormone. Researchers even discovered that just five days of short sleep – sleeping less than seven hours a night – can increase food intake and weight gain. Make it a goal to get from seven to nine hours per night of refreshing sleep.
Manage your stress
Ongoing stress increases cortisol, wreaks havoc on glucose and insulin, and slows metabolism. To help boost your metabolism, you'll want to incorporate at least 10 minutes a day of active stress management, like meditation, breathwork, gentle yoga, or crafts. (Extra benefit: a daily stress management practice helps your thyroid and immune health too!)
A note from Paloma Health
It's vital for anyone struggling to lose weight with a slow metabolism to ensure that they have a properly functioning thyroid. To develop a health plan that best supports your metabolic health, consider meeting with a Paloma Health thyroid doctor or thyroid nutritionist.