What can slow my metabolism?
Metabolism includes all of the biochemical reactions in your body that use nutrients and oxygen to create energy.
There are multiple factors which affect how quickly (or slowly) yours works. We call this your “Metabolic Rate”.
Common reasons why metabolic rate can slow down:
- Low thyroid hormone (called Hypothyroidism)
- History of crash-dieting or yo-yo dieting
- Body size and composition
- Activity level
- Lack of regular sleep (also called “chronic sleep deficit”)
I’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 diseases and mineral deficiencies (e.g. iodine or selenium) for example.
Tip: If you’re experiencing any of the above symptoms and don’t already get your blood drawn annually talk with your doctor about having your thyroid hormones tested.
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 the amount of fat, it can, unfortunately, also lead to a reduction in the amount of muscle you have. This occurs when your body doesn’t get the nutrients it requires from your intake of food. Your body’s goal is to get its nutrients from somewhere. If you’re restricting your intake, your body will break down its own muscle tissue as an energy source. As you know more muscle means a faster resting metabolic rate, whereas less muscle requires less energy and a lower resting metabolic rate.
Tip: Make sure you’re eating enough food to fuel your body by eating a variety of lean meats, whole grains, and heart-healthy fats.
Your size and body composition
In general, larger people have faster metabolic rates than smaller people. That is because it takes more energy to fuel a larger body.
This doesn’t mean that if you are taller or weigh more than your peers that you can eat anything you want. On the contrary, maintaining a healthy weight is your best bet. Not sure what a “healthy weight” is? (Hint: It’s not necessarily what you weighed your Senior year of High School), check with your doctor, consult with a Nutritionist or Registered Dietician.
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, so if you don’t already, add weight lifting to your routine. Studies show that the “fat burning” benefits of cardiovascular (cardio) exercise, only occur during the time that you are performing it. Once you stop, the increased calories that you were burning also stop. With weight lifting, however, the benefits are greater. Muscles burn calories all the time. Larger muscles burn more calories even while you’re at rest!
Tip: Add weight training to your routine to help increase your muscle mass.
While aerobic exercise only temporarily increases your metabolic rate, it doesn’t mean you should give it up altogether. 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, especially if you have a desk job. Take walks in the morning or evening. Park further away. Exercise regularly.
Lack of regular 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. If you find that your eating and exercise habits are on point and you don’t have any metabolic issues contributing to weight gain, sleep issues may be the reason. You can read more about that here!
Tip: Try to create a routine that allows at least 7 hours of sleep every night.