10 Things You May Not Realize Affect Your Metabolism

“It’s all fun and games until your metabolism slows down.” Why is it that one person never has to watch what they eat, while another person feels like every snack shows up on the scale?

There are some common myths about metabolism, such as, your metabolism can’t change because of genetics. And while genetics do play a role in how our metabolism functions, it’s not the only deciding factor. Other common myths surrounding metabolism include slowing down as you age or after eating late at night.

So what is your metabolism, and how does it impact your overall health and wellbeing? In the guide below, we discuss how your metabolism works, what factors can impact your metabolism - including chronic health issues like diabetes - and how even weather can play a role in burning off those calories.

What Is Metabolism?

Metabolism is the internal process by which your body expends energy and burns calories when you eat. The amount of energy is measured in kilojoules (or calories), and the calorie content of foods depends on the amount of carbohydrates, fats and proteins in the food, along with portion size.

The metabolism process works at different intensities for different people, and can be affected by a number of factors. A fast metabolism will burn calories at a quicker rate, so when it comes to gaining or losing weight, metabolism can play a part – but it’s not the entire driving factor. For many people, age, diet and activity levels are the main components to metabolism and weight.

Basal Metabolic Rate (BMR)

Even at rest, the body needs energy to keep functioning - life sustaining functions include heartbeat, breathing, blood circulation and cell repair - and this energy is represented in the body’s basal metabolic rate (BMR). The largest amount of energy expended each day, BMR accounts for an estimated 50 to 80% of your daily energy use.

Diabetes And Metabolism

The metabolism of those with type 1 or type 2 diabetes will be different, attributed to the insulin resistance and potential metabolic syndrome. Because diabetes impairs the body’s ability to metabolize glucose, when blood sugars are elevated, weight gain is more likely and resistance to insulin can increase.

Type 1 diabetes, also described as insulin dependent diabetes, is an autoimmune disease that destroys insulin-producing cells in the pancreas, preventing the body from producing enough insulin. It requires regular insulin administration by injection or insulin pump.

Type 2 diabetes, on the other hand, is usually caused by other factors (such as obesity or genetics), and may cause the body to produce more insulin to compensate for the fact that the body can’t use its own insulin effectively enough.

Weight gain or unexplained weight loss, excessive thirst, increased urination and hunger, tiredness and fatigue can be some common symptoms for those with diabetes.

Factors That Can Affect Our Metabolism And BMR

There are a handful of factors that can influence our metabolism and BMR, from internal to external forces at work.

1. Body size, lean muscle and body fat

Increasing muscle mass can improve metabolism and is crucial to maintaining blood glucose control and energy balance, according to one study.

Skeleton muscle insulin resistance is a condition where the muscles in the body don’t respond as well to insulin, and is a predictor of type 2 diabetes. In one study, increasing muscle mass showed metabolic benefits, and lean mass is typically associated with reduced incidence of insulin resistance, or metabolic syndrome.

If most of the fat is around the waist rather than hips, there is a higher risk for heart disease and type 2 diabetes, with risk increasing when waist size is greater than 35 inches for women or 40 inches for men.

2. Diet

Weight loss and maintenance has a direct link to improving metabolic diseases, such as hypertension and type 2 diabetes. At a metabolic level, weight loss really means your body is in a continuous metabolic adaptation process.

When dieting, the main goal is that food intake is less than the energy spent on metabolic activities (including physical activity and BMR). However, if the diet is too restrictive, your body may break down muscle for energy, which could slow down your metabolism.

At the end of the day, a balanced lifestyle of healthy eating habits, exercise and sleep will help maintain a good metabolism.

3. Age

Age isn’t quite as impactful to metabolism as once believed. According to one study, the BMR expenditure between 20 to 60 years old remained relatively stable, but did start to show some decline around age 60.

4. Gender and hormonal influences

Biological sex plays a significant role in developing metabolic diseases (such as diabetes) and cardiovascular diseases. Estrogen therapy has been shown to improve cardiovascular health and insulin sensitivity, according to some studies.

5. Genetics

There are more than a thousand inherited metabolic disorders caused by gene changes, and can be passed down by one or both parents. A metabolic disorder may affect how the body makes energy (breaking down foods or chemicals), or breaking down and getting rid of substances that the body no longer needs.

6. Illness and metabolic diseases

We’ve already discussed how diabetes can affect metabolism, but there are a number of others that can complicate how metabolism functions. Metabolic disease is only classified as such if a critical enzyme is disabled (like insulin), or if the control of the metabolic pathway is affected.

Some of the other metabolic diseases include hereditary hemochromatosis, Lesch-Nyhan syndrome, obesity, pancreatic cancer, Tangier disease, and more.

7. Physical activity levels

Energy is used by physical activity, which can include a planned exercise (like running or playing a sport), or even just cleaning, running errands and chasing after kids and pets. For a moderately active person, this is about 20% of daily energy use.

According to the Office of Disease Prevention and Health Promotion (Health.gov), adults should do at least 150 minutes to 300 minutes a week of moderate-intensity physical activity, or 75 to 150 minutes of vigorous-intensity aerobic activity.

It’s suggested that weight training is one of the best activities, and combining adequate protein intake plus increasing muscle mass is the best way to boost metabolism. Other exercise options include adding high-intensity interval training (HIIT) to your routine, which is supposed to help keep your metabolism high for as much as a full day.

How Weather Can Affect Metabolism

It may be somewhat surprising, but the environment and weather can also play a role in your metabolism. From pollution to temperature, there can be certain negative impacts causing weight gain and metabolic problems.

1. Air Pollution

We’ve discussed before the link between air pollution and increased type 2 diabetes risk. Climate is intertwined with our daily lives, and changes can disrupt our quality of food and water, shelter and air.

Health risks from air pollution include respiratory and cardiovascular health effects, and those who suffer from a chronic disease can experience heart palpitations, fatigue, lightheadedness and shortness of breath when air pollution is high and air quality is poor.

Add in wildfire smoke and allergens, and you’ll have a perfect storm for poor breathing quality. According to one study, diabetes prevalence increased with higher exposures to the fine particulate matter in the air.

2. Cool Temperatures

There are several types of fat:

• White fat: Stores extra energy. Too much white fat is characteristic of obesity, risks for type 2 diabetes and other diseases.
• Brown fat: Burns chemical energy to create heat and maintain body temperature.

According to researchers, white fat cells in both animals and humans will take on characteristics of brown fat cells in response to cold. One 2013 study found that even small reductions in ambient temperature can increase brown fat activity. However, following periods of neutral temperature or warm exposure, the changes were completely reversed. More recent studies are still being conducted into how brown fat cells could be leveraged for weight loss.

It’s also important to note that winter can be a time of weight gain, with lower activity levels due to extreme temperature changes and dietary habits around the holidays.

3. Hot Temperatures

As with cool weather, in hot weather the body has to work harder to maintain its normal temperature, which can increase the BMR. Add in physical activity, and your body will need plenty of energy to burn at a faster rate. According to one study, as temperature increases, the rate of metabolism in an organism should increase and then rapidly decline at higher temperatures.

Learn More About Diabetes

If you’ve been diagnosed with diabetes (or wonder if you could be displaying the symptoms but have not been diagnosed), it's important to discuss your concerns with your physician or other specialist.

If you want to find out more information about other chronic health and skin conditions, be sure to check out more of The Weather Channel’s health and wellness coverage, including guides and videos on important topics including psoriasis, eczema, weight loss and other tips to live a healthier lifestyle.

The Weather Company does not provide medical advice, diagnosis, or treatment. Talk with your doctor before starting any new medicine, supplement, weight loss or exercise regimen.

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