Metabolism is a word that comes up a lot when it comes to weight loss, and it’s obvious why – Your metabolism is the engine that drives your body. If it’s a little slow, you may feel tired, sluggish and, of course, feel like you’re gaining weight.
If your metabolism is fast then you’re not reading this because you’re probably out eating an entire pizza and not giving a s**t.
The thing is that our metabolisms can naturally drop about 5% for every decade after 40. So, if your BMR (Basal Metabolic Rate) is 1400 at 40, over the course of the next 10 years, often less because the metabolism slows faster as we age (I know – not fair), that means you may need up to or more than 150 calories less to maintain your weight.
And most of us are not correcting for those unneeded calories, right?
The Basics of Your Metabolism
Your metabolism describes pretty much everything that happens in your body – Everything your body needs to do to stay alive. So, when we talk about increasing our metabolisms, we’re basically saying we want our bodies to burn more calories each day, which will leads to weight loss, right?
Well, it’s obviously not that simple because there are a variety of reasons your metabolism may slow down other than getting older. Let’s delve in, shall we?
What can slow my metabolism?
You already know that your 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).
That’s why the whole calories in/calories out adage is pretty much crap when it comes to weight loss. Your metabolism is much more complicated than that, but there are some common reasons for a metabolic 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
Thyroid hormones directly regulate your metabolic rate and your body weight. It’s pretty much 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 diseases and mineral deficiencies (e.g. iodine or selenium) for example.
Symptoms of an Underactive Thyroid
- Unable to sleep
- Mood swings
- Weight gain
- Depression and/or irritability
- Feeling cold
- Brain fog
There are more and, obviously, these symptoms can crossover into other issues, so they don’t necessarily mean a thyroid problem. The only way to know that is to get to your doctor and get your thyroid tested.
What causes Underactive Thyroid
- Family history
- Autoimmune diseases such as diabetes, rheumatoid arthritis or lupus
- Medications such as steroids or lithium
- Swelling of the thyroid
Tip: Talk with your doctor about having your thyroid hormones tested.
Your history of dieting
Most of us have spent a large part of our lives dieting. A diet basically comes down to cutting calories enough that you lose weight. The trouble is, diets don’t work for the long term.
When you cut your calories too low, your metabolism actually slows down. On top of that, just losing weight at all causes your metabolic rate to slow down. This is because the body senses that food may be scarce and adapts by trying to keep all your life functions going, but doing it all with less food.
So, here’s the deal:
- Dieting without exercise can reduce fat, but it can also reduce the amount of muscle you have. Muscle is more metabolically active than fat, so when you lose it, your metabolism slows down.
- When you diet and then go off the diet (as we do), your new metabolic rate is based on the new body mass – especially the amount of muscle you have.
- According to one study published in the International Journal of Endocrinology, when dieters got to their goal weight, their metabolic rate was severely depressed. They experienced immediate weight gain once they went back to their regular diets.
The bottom line is to avoid cutting your calories so low that your metabolism thinks there’s no food available and shuts down.
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. No that doesn’t mean you should gain weight to increase your metabolism. Obviously, if that worked we would all be sitting around in our bathing suits basking in the glow of life.
You can’t always change your body type or your frame size, but one that you can change is your body composition. This is key to increasing your metabolism and losing fat. In fact, it’s much more important than a number on the scale.
So, how do you change your body composition? Besides your diet (adding more protein helps) and cardio exercise, there’s something else that really helps:
When you lift weights, you can increase your metabolism by more than 50 calories a day, which helps close the gap between how much you’re eating and how much you’re burning.
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.
If you’re new to strength training, start with a Basic Total Body Workout about 2-3 days a week. Even using light weights can help you build lean muscle tissue and change your metabolism.
Which leads us to…
Your activity level
Now, while strength training and lean muscle tissue give you a long-term metabolic boost, cardio exercise actually temporarily increases your metabolic rate. Your muscles are burning fuel to move and do “work” and you can tell because you’re also sweating, your heart rate is up and you feel like you’re exercising.
Try to get in regular cardio exercise every day like:
- Cardio machines – Treadmill, elliptical, etc.
- Home workouts such as this Low Impact Cardio Workout
And don’t forget 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.
That’s all part of the other equation for your metabolism – Non-Exercise Activity Thermogenesis or NEAT. NEAT comprises the energy expenditure of all daily activities that aren’t planned exercise – Sitting, standing, fidgeting, basically any movement you do.
Get More NEAT
- Walk more – at lunch, after dinner, to the store, around the block, etc.
- Play with your dog
- Wash your car by hand
- Park further away when you’re shopping
- Lap the park when you’re watching your kid’s game
- Work in the yard or do more chores around the house
- Use the bathroom on a different floor
Lack of sleep
There is plenty of research that shows the influence that sleep has on your metabolic rate. In fact, in one study published in the International Journal of Endocrinology, researchers had healthy participants sleep for 4 hours a night for 6 nights, followed by 12 hours of sleep for 7 nights.
The findings? Even just a week of sleep deprivation resulted in significant drops in metabolism. Lack of sleep also changes your ‘hunger’ hormones, making your hungrier than you normally would be.
That could lead to overeating without you even realizing it. The general consensus is to get 7-9 hours of sleep every night.
Tip: Try to create a routine that allows at least 7 hours of sleep every night. Go to sleep at the same time if you can and get up at the same time. Practice as much as you can and, if you can’t get it all in, try power naps.
More: How to Sleep Better
Recipe: Boost Your Metabolism
The following recipe contains selenium, a supplement that can help your thyroid stay healthy and keep your metabolism going.
Recipe (Selenium-rich): Chocolate Chia Seed Pudding
½ cup Brazil nuts
2 cups water
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: Make a simple delicious breakfast or dessert topped with berries.
Connolly J, Romano T, Patruno M. Effects of dieting and exercise on resting metabolic rate and implications for weight management. Fam Pract. 1999;16(2):196-201. doi:10.1093/fampra/16.2.196
Kinucan, P. Kravitz, L. Controversies in Metabolism. IDEAfit.com
Mullur R, Liu Y-Y, Brent GA. Thyroid Hormone Regulation of Metabolism. Physiol Rev. 2014;94(2):355-382. doi:10.1152/physrev.00030.2013