Understanding Metabolism in Grand Rapids, Michigan

Metabolism is the term for all the chemical processes that continuously occur in your body to keep you alive and functioning. These processes help you:

  • Break down nutrients from the foods you eat
  • Build and repair tissues like muscle, skin, and organs
  • Maintain a stable internal environment (homeostasis)

All of this work requires energy, which ultimately comes from your food. How much energy your body burns at any given time is influenced by your metabolic rate.

In Grand Rapids, where winters are long and cold and physical activity can drop when it’s icy or snowy, understanding your metabolism can help you manage your weight and overall health year-round.

Metabolism and Weight: A Balancing Act

Maintaining a healthy weight is about balancing:

  • Energy in – the kilojoules (or calories) you get from food and drinks
  • Energy out – the kilojoules your body uses to function and move

If you regularly eat and drink more energy than your body uses, the extra is stored, mostly as fat. If you use more energy than you take in, your body will draw on stored fat and, sometimes, muscle.

Most of the energy you burn each day is not from exercise, but from simply keeping your body alive and working.

The Two Main Processes of Metabolism

Metabolism has two main parts:

1. Catabolism (Breaking Down)

Catabolism is the breakdown of food components, such as:

  • Carbohydrates
  • Proteins
  • Fats

into simpler forms that your body can:

  • Use to provide energy
  • Use as basic building blocks for growth and repair

2. Anabolism (Building Up)

Anabolism is the part of metabolism that:

  • Builds and repairs tissues (muscle, bone, organs, skin)
  • Supports growth, especially in children and teens
  • Requires energy from your food

When you eat more than your body needs for daily anabolism and activity, the extra nutrients are typically stored as fat.

Components of Your Metabolic Rate

Your total energy expenditure (or metabolic rate) has three main parts:

1. Basal Metabolic Rate (BMR)

Your BMR is the amount of energy your body needs at rest to:

  • Breathe
  • Keep your heart beating and blood circulating
  • Maintain body temperature
  • Grow and repair cells
  • Adjust hormone levels and support brain function

BMR accounts for about 50–80% of your daily energy use.

Average BMR values (approximate):

  • Men: around 7,100 kJ per day
  • Women: around 5,900 kJ per day

2. Thermic Effect of Food (Thermogenesis)

This is the energy your body uses to:

  • Eat
  • Digest food
  • Absorb, transport, and store nutrients

Thermogenesis accounts for about 5–10% of your daily energy use.

Different foods affect this differently:

  • Fats: raise BMR by about 0–5%
  • Carbohydrates: raise BMR by about 5–10%
  • Proteins: raise BMR by about 20–30%

Hot, spicy foods (such as those containing chili, horseradish, or mustard) can also have a noticeable thermic effect.

Your BMR rises soon after you begin eating and typically peaks about 2–3 hours later. The increase can range from 2% to 30%, depending on the size and type of meal.

3. Energy Used During Physical Activity

This is the most variable part of your metabolism and includes:

  • Planned exercise (walking, running, cycling, gym workouts)
  • Everyday movement (cleaning, gardening, walking around at work, shoveling snow in a Grand Rapids winter)

For a moderately active person (30–45 minutes of moderate-intensity physical activity per day), this component contributes about 20% of daily energy use.

During strenuous or vigorous physical activity, your muscles may burn up to 3,000 kJ per hour. While muscles at rest use about 20% of your total energy expenditure, during intense exercise this can increase 50-fold or more.

Energy used during physical activity is the only part of metabolism you can directly control day to day.

Basal Metabolic Rate (BMR) and Muscle Mass

Your BMR is largely determined by your lean body mass, especially muscle mass. Lean tissue requires more energy to maintain than fat tissue. Therefore:

  • More muscle = higher BMR
  • Less muscle = lower BMR

Anything that reduces lean muscle (such as prolonged inactivity, crash dieting, or ageing without strength training) will reduce your BMR.

Because BMR makes up such a large portion of your total energy use, preserving or increasing muscle mass is crucial if you’re trying to:

  • Lose weight
  • Maintain weight loss
  • Stay strong and active as you age

Why Strength Training Matters in Grand Rapids

Combining regular physical activity—particularly weight-bearing and resistance exercises—with healthier eating patterns is more effective than dieting alone. Eating too few kilojoules (or calories) can cause your body to slow your metabolism to conserve energy.

Benefits of maintaining lean muscle mass:

  • Helps keep your BMR higher
  • Reduces the risk of injury during activities like shoveling snow, walking on ice, or recreational sports along the Grand River
  • Supports balance and mobility as you get older
  • Increases your daily energy expenditure, even at rest

If you’re over 40, have a chronic condition (such as diabetes, heart disease, or arthritis), or haven’t exercised recently, talk with a local Grand Rapids provider—such as a primary care doctor at Corewell Health (formerly Spectrum Health), Trinity Health Grand Rapids, or Metro Health – University of Michigan Health—before starting a new fitness program.

Factors That Affect Your BMR

Your BMR is influenced by several factors working together:

Body Size

  • Larger adult bodies have more metabolizing tissue and generally a higher BMR.

Amount of Lean Muscle Tissue

  • More muscle mass increases BMR.
  • Loss of muscle (due to inactivity, ageing, or illness) lowers BMR.

Amount of Body Fat

  • Fat tissue burns less energy than muscle at rest, so a higher body fat percentage usually means a lower BMR compared with someone of the same weight but more muscle.

Crash Dieting, Starving, or Fasting

  • Severe calorie restriction can cause BMR to drop by up to 15%.
  • If muscle tissue is also lost, BMR falls even further.

Age

  • Metabolism generally slows with age due to:
    • Loss of muscle mass
    • Hormonal changes
    • Changes in the nervous system

Children and teens in Grand Rapids have higher energy needs per kilogram of body weight because they are growing and need extra energy to maintain body temperature—especially during cold Michigan winters.

Growth

  • Infants, children, and adolescents have higher BMRs due to the demands of growth and development.

Gender

  • On average, men have higher BMRs than women, largely because they tend to have:
    • Larger bodies
    • More muscle mass

Genetic Predisposition

  • Your genes help determine your metabolic rate.
  • Some people naturally burn energy faster or slower than others.

Hormonal and Nervous System Controls

  • BMR is regulated by your nervous system and hormones.
  • Hormonal imbalances (such as thyroid disorders) can speed up or slow down metabolism.

Environmental Temperature

  • In very cold or hot conditions, your body works harder to maintain a normal internal temperature, which can increase BMR.
  • In Grand Rapids’ cold winters, your body may use more energy to stay warm, especially if you spend time outdoors.

Infection or Illness

  • During infections or illnesses, BMR often increases because your body:
    • Builds new tissues
    • Mounts an immune response

Amount of Physical Activity

  • Regular physical activity and exercise:
    • Increase muscle mass
    • Teach your body to burn energy more efficiently
    • Can raise your BMR over time

Drugs and Substances

  • Caffeine and nicotine can increase BMR temporarily.
  • Some medications may also affect metabolism.

Dietary Deficiencies

  • Certain deficiencies, such as low iodine intake, can reduce thyroid function and slow metabolism.

Physical Activity and Metabolism in Grand Rapids

Energy expenditure is continuous, but the rate varies throughout the day and is usually lowest in the early morning.

The United States physical activity guidelines recommend that adults aim for at least:

  • 150 minutes of moderate-intensity aerobic activity per week, or
  • 75 minutes of vigorous-intensity activity per week, plus
  • Muscle-strengthening activities on 2 or more days per week

In practical terms:

  • Moderate exercise: you can talk while exercising, but you can’t sing
  • Vigorous exercise: you can’t say more than a few words without pausing for breath

In Grand Rapids, you can stay active year-round by:

  • Walking or biking on the Kent Trails or Grand River Edges Trail in warmer months
  • Using indoor facilities at local gyms, community centers, or hospital wellness programs during winter
  • Taking advantage of indoor walking tracks and mall walking when sidewalks are icy

It’s also important to limit sedentary time (sitting or lounging) and break up long periods of sitting with short movement breaks.

Muscle, Age, and Metabolism

Muscle Tissue Has a Big Appetite for Energy

The more muscle mass you have, the more kilojoules (or calories) you burn—even when you’re resting. Many people gain fat as they age, partly because:

  • Muscle mass gradually decreases
  • Activity levels often drop, especially in colder months

Research shows that strength training and resistance exercises can reduce or prevent age-related muscle loss. This is especially important for adults in midlife and older adults in the Grand Rapids area, where slippery winter conditions can increase fall risk if strength and balance are poor.

Hormonal Disorders That Affect Metabolism

Hormones help regulate metabolism. Some common hormonal disorders involve the thyroid gland, located in your neck. This gland produces hormones that help control energy expenditure.

Hypothyroidism (Underactive Thyroid)

Hypothyroidism occurs when the thyroid gland does not release enough thyroid hormones, causing metabolism to slow down.

A common cause is Hashimoto’s disease, an autoimmune condition.

Symptoms may include:

  • Unexplained weight gain
  • Fatigue or lethargy
  • Depression or low mood
  • Constipation
  • Feeling cold more easily (especially noticeable in Michigan winters)

Hyperthyroidism (Overactive Thyroid)

Hyperthyroidism occurs when the thyroid gland releases more hormones than the body needs, speeding up metabolism.

The most common cause is Graves’ disease.

Symptoms may include:

  • Increased appetite
  • Unintentional weight loss
  • Nervousness or anxiety
  • Rapid heartbeat
  • Diarrhea
  • Feeling hot or sweating more than usual

If you notice these symptoms, schedule an appointment with your Grand Rapids primary care provider or an endocrinologist at a local system such as Corewell Health, Trinity Health Grand Rapids, or Metro Health.

Genetic (Inherited) Metabolic Disorders

Your genes act as blueprints for the proteins in your body, including those that help digest and metabolize food. Sometimes, a faulty gene leads to a protein that doesn’t work properly, causing a genetic metabolic disorder.

These conditions are usually diagnosed and managed by specialists, often in collaboration with major hospitals and pediatric centers in Michigan.

Common examples include:

Fructose Intolerance

  • Inability to properly break down fructose, a sugar found in:
    • Fruit and fruit juices
    • Table sugar (sucrose)
    • Honey
    • Certain vegetables

Galactosaemia

  • Inability to convert the carbohydrate galactose into glucose
  • Galactose is produced when lactose (milk sugar) is broken down in the digestive system
  • Sources of lactose include:
    • Milk
    • Yogurt
    • Cheese
    • Other dairy products

Phenylketonuria (PKU)

  • Inability to convert the amino acid phenylalanine into tyrosine
  • High levels of phenylalanine can cause brain damage if not treated
  • People with PKU must avoid:
    • High-protein foods (such as meat, fish, eggs, and some dairy)
    • Foods and drinks containing the artificial sweetener aspartame

Most genetic metabolic disorders can be managed with:

  • Careful, lifelong dietary planning
  • Regular medical follow-up

Because their symptoms can resemble other conditions, it’s important to see a doctor if you suspect a metabolic disorder.

Local Support and Resources in Grand Rapids, MI

If you have questions about your metabolism, weight, or thyroid health, or you’re concerned about a possible metabolic disorder, you can seek help from:

  • Your GP / Primary Care Provider
    • At practices affiliated with Corewell Health (Spectrum Health), Trinity Health Grand Rapids, Metro Health – University of Michigan Health, or Mercy Health
  • Endocrinologists
    • Specialists in hormone and metabolic disorders
  • Registered Dietitians and Nutritionists
    • Available through local hospitals, private practices, and community health centers
  • Kent County Health Department and Grand Rapids Public Health Programs
    • Offer community health resources, nutrition education, and chronic disease management support

Key Points About Metabolism and Your Health

  • Achieving or maintaining a healthy weight is a balancing act between energy intake and energy expenditure.
  • BMR is the amount of energy your body needs to maintain homeostasis at rest and makes up most of your daily energy use.
  • Men generally have higher metabolisms than women because they tend to be larger and have more muscle mass.
  • BMR increases during growth, illness, and when your body is building new tissues or mounting an immune response.
  • Your BMR rises after you eat because your body uses energy to digest and metabolize food.
  • Regular physical activity and strength training are key to maintaining muscle mass and supporting a healthy metabolism, especially in a seasonal climate like Grand Rapids.

If you’re unsure where to start, consider scheduling a wellness visit with a local provider or asking for a referral to a registered dietitian or exercise specialist in the Grand Rapids area.