Why is My Metabolism Slow?

If you’ve gained weight and/or feel cold and tired it may just be that you have a slow metabolism. 

The next question of course is “why is my metabolism slow”? 

Well, that’s a great question!  Since your metabolism is how your body takes food and oxygen and uses it to fuel all of its biochemical reactions there are a lot of things that can slow it down. 

In this post we’ll talk about five common reasons your metabolism could be slow (plus we’ve included a link to our FREE 7 Day Hormone Reboot) including: thyroid hormones, history of dieting, size and body composition, activity level, and lack of sleep.  I’ve also included a tip that you can try for each one of these possible “metabolism busters”. 

Plus I’ll share one of my delicious thyroid-loving mineral-containing recipes that you can make for breakfast or dessert.

Why is My Metabolism Slow?

You may feel tired, cold or that you’ve gained weight.  Maybe your digestion seems a bit more “sluggish”.

You may be convinced that your metabolism is slow.

Why does this happen?  Why do metabolic rates slow down?

What can slow my metabolism?

Metabolism includes all of the biochemical reactions in your body that use nutrients and oxygen to create energy.  And there are lots of factors that affect how quickly (or slowly) it works, i.e. your “metabolic rate” (which is measured in calories).

But don’t worry – we know that metabolic rate is much more complicated than the old adage “calories in calories out”!  In fact it’s so complicated I’m only going to list a few of the common things that can slow it down.

Examples of common reasons why metabolic rates can slow down:

●     low thyroid hormone
●     your history of dieting
●     your size and body composition
●     your activity level
●     lack of sleep

We’ll briefly touch on each one below and I promise to give you better advice than just to “eat less and exercise more”.

Low thyroid hormones

Your thyroid is the master controller of your metabolism.  When it produces fewer hormones your metabolism slows down.  The thyroid hormones (T3 & T4) tell the cells in your body when to use more energy and become more metabolically active.   Ideally it should work to keep your metabolism just right.  But there are several things that can affect it and throw it off course.  Things like autoimmune disease, mineral deficiencies (e.g. iodine or selenium) and hormone imbalances for example.

Tip: Talk with your doctor about having your thyroid hormones tested.  If you are going to go this route, you want to make sure to have a full thyroid panel done, not just TSH.  TSH can tell us some things about your thyroid health, but you can have normal TSH levels with abnormal T3 and T4 levels. It’s just doesn’t give a full picture.

Your history of dieting

When people lose weight their metabolic rate often slows down.  This is because the body senses that food may be scarce and adapts by trying to continue with all the necessary life functions and do it all with less food.

While dieting can lead to a reduction in amount of fat it unfortunately can also lead to a reduction in the amount of muscle you have.  As you know more muscle means faster resting metabolic rate.

Tip: Make sure you’re eating enough food to fuel your body without overdoing it.

Your size and body composition

In general, larger people have faster metabolic rates.  This is because it takes more energy to fuel a larger body than a smaller one.

However, you already know that gaining weight is rarely the best strategy for increasing your metabolism.

Muscles that actively move and do work need energy.  Even muscles at rest burn more calories than fat.  This means that the amount of energy your body uses depends partly on the amount of lean muscle mass you have.

Tip: Do some weight training to help increase your muscle mass.

Which leads us to…

Your activity level

Aerobic exercise temporarily increases your metabolic rate.  Your muscles are burning fuel to move and do “work” and you can tell because you’re also getting hotter.

Even little things can add up.  Walking a bit farther than you usually do, using a standing desk instead of sitting all day, or taking the stairs instead of the elevator can all contribute to more activity in your day.

Tip:  Incorporate movement into your day.  Also, exercise regularly.

Lack of sleep

There is plenty of research that shows the influence that sleep has on your metabolic rate.  The general consensus is to get 7-9 hours of sleep every night.

Now as great as that sounds, what if you just can’t. What happens if you go to bed at a reasonable time but you wake up in the middle of the night and just can’t get back to sleep, no matter how hard you try.

This is a good indicator of hormone imbalances often caused by adrenal fatigue.  The adrenals are the major regulator of your hormone health, and when you are stressed (the body recognizes all stress the same) from life, from work, from traffic, from all the day to day things you have on your list to do or from a major stress that happens suddenly, the body recognizes it all the same. When this happens, the adrenals will pump out high levels of cortisol while you are fight or flight to protect you from what it perceives s imminent danger.  These high levels during the day can completely mess with your circadian rhytms and wake you up at night when you should be sleeping!

This is one of the biggest reasons why you may have a slow metabolism and why regular weight loss programs may not work for you.  If you don’t address the cause (hormone imbalances and adrenal fatigue) then a slow metabolism and added weight may be your least best friend right now.  The great news is, you can reset your hormones which can make a huge difference in how you sleep at night.  If you’re struggling to sleep at night, I highly recommend signing up for our FREE 7 Day Healthy Hormone Reboot to get your sleep patterns back on track!

Tip: Try to create a routine that allows at least 7 hours of sleep every night.  There’s some great tips in our Blog Post Bye Bye Sleeping Through the Night.

Recipe (Selenium-rich): Chocolate Chia Seed Pudding


Serves 4


½ cup Brazil nuts
2 cups water
nut bag or several layers of cheesecloth (optional)
½ cup chia seeds
¼ cup unsweetened cacao powder
½ teaspoon ground cinnamon
¼ teaspoon sea salt
1 tablespoon maple syrup


Blend Brazil nuts in water in a high-speed blender until you get smooth, creamy milk.  If desired, strain it with a nut bag or several layers of cheesecloth.

Add Brazil nut milk and other ingredients into a bowl and whisk until combined.  Let sit several minutes (or overnight) until desired thickness is reached.

Serve & Enjoy!

Tip:  Makes a simple delicious breakfast or dessert topped with berries.