weight loss · May 02, 2025

Understanding Your Metabolism: How It Works and How to Support It

two women doing yoga to support metabolism

By Emily Johnson, MS, RD

You’ve probably heard people say they have a “fast metabolism” and can eat whatever they want. Conversely, they may bemoan their slow metabolism, saying it causes them to gain weight. While it’s true that metabolism has to do with the food you eat, it’s so much more than just how fast or slow you burn calories.

But how exactly does your metabolism work, and how can you support it? In this article, we’re breaking down how metabolism works, how it relates to longevity and body weight, and what you can do to support a healthy metabolism for a long, healthy life.

What Is Metabolism?

Metabolism is a crucial system to your overall health, and it affects countless processes throughout the body. It works to maintain your body temperature, get your muscles in motion, and provides the energy to power all chemical reactions necessary for keeping you alive and well. At its most basic, your metabolism refers to how your body processes and utilizes the food you eat for energy production, hormonal regulation, and cellular function [1, 2, 3].

While metabolism is related to metabolic health, it is not the same thing. Metabolic health refers to the efficiency of your metabolism (how well it works), while metabolism is simply the process for converting food into energy. Metabolic health encompasses how well your body regulates blood sugar levels, responds to insulin, and maintains weight. Among other things — metabolism helps you regulate these systems and supports your metabolic health. Simply put, when you’re metabolically healthy (your metabolism is working as it should), you feel better in your day-to-day life, you have stable energy levels, quality sleep, get enough activity, and are adept at managing stress.

Metabolism indeed helps you burn calories and maintain weight, but in reality, metabolism is just a small piece of the weight and body composition puzzle. Metabolism encompasses three main components:

Basal Metabolic Rate: Basal metabolic rate, or BMR, is the minimum number of calories your body requires to keep all of your basic functions — like breathing, digestion, circulation, and cell production — up and running. In other words, it is the least amount of energy needed to keep you alive when you are doing nothing. When it comes to weight loss, understanding your BMR is helpful, as it helps you determine how high your caloric intake should be to lose weight, while keeping your body functioning efficiently.
Thermic effect of food: The thermic effect of food refers to the calories your body burns when ingesting, breaking down, and absorbing the food you eat. Of course, the food you eat generally involves the intake of far more calories than the amount of calories required to digest it, but certain foods, like high fiber and high protein foods, require more energy to process. These foods are great for metabolism because they are low in calories and your body burns more calories to digest them (compared to fat and simple carbohydrates). You can eat more of these foods, stay fuller for longer, support muscle mass, and keep your metabolism humming, all while still making progress towards your weight loss goals.
Activity thermogenesis: Also known as non-exercise activity thermogenesis (NEAT), activity thermogenesis refers to the calories you burn doing movement throughout the day, excluding planned exercise sessions. Walking to your car after work, taking the stairs, cleaning your house, even snapping your fingers — all of these things are ways your body burns calories by moving, and fall under activity thermogenesis. If you are trying to lose weight, increasing your activity thermogenesis by moving more throughout the day is a great way to support your efforts.

How Does Metabolism Work?

When you eat a meal, your body breaks down the macronutrients in foods to be used as energy. Carbohydrates, fat, and protein are all broken down into their simplest molecular parts by digestive enzymes and are absorbed into the bloodstream. Through this process, carbohydrates become simple sugars, like glucose; fat becomes fatty acids; and protein becomes amino acids.

From there, these molecular parts of food are transported throughout the body and taken to cells, where they are processed into the smallest possible units of energy, called adenosine triphosphate, referred to as ATP [4]. ATP is the energy source for all processes in the body — it powers your heart, lungs, brain, and every other system in the body.

This process of metabolising food for energy results in two separate processes that occur simultaneously in the body: anabolism and catabolism.

Anabolism vs. catabolism

Anabolism and catabolism are like two sides of the same coin — both processes are essential to fueling your everyday activities and maintaining health.

Anabolism refers to the work metabolism does to build and restore the body. It accomplishes this by way of cell growth, maintenance of tissue, and storing energy (in the form of glucose and glycogen) for crucial bodily functions. It requires tiny units of energy to be joined to form more complex molecules, which are used for restoration and preservation. In other words, anabolism involves building more complex molecules from simpler ones, using energy in the process.

Catabolism refers to the intentional breakdown of tissues to provide fuel for critical functions. Larger molecules from carbs and fat are broken down by the cells to release energy, which powers anabolism, keeps your body temperature regulated, and provides muscles with energy to move your body. In other words, catabolism involves breaking down more complex molecules into simpler ones, releasing energy in the process.

What factors affect metabolism?

Metabolism is a chemical process required to keep your body alive and well. Several things can help or hurt your metabolism.

Age: As you get older, your metabolism slows down. Research shows that metabolism decreases by 0.07% each year after age 60, so it’s important to eat a healthy diet and stay active with aerobic and resistance training to maintain a healthy weight and muscle mass as you age [5, 6].
Muscle mass: Muscles at rest burn more calories than fat at rest, so having a higher amount of muscle mass will help you burn more calories overall, even when you are just sitting on the couch.
Hormones: Thyroid, insulin, and cortisol are all hormones that can help or hurt your metabolism. Low thyroid function, high circulating insulin levels, and high cortisol can all slow your metabolism. Ask to have these levels checked via blood test at your annual physical.
Genetics: Your genetics play a role in metabolism, and while you can’t control your genes, you can control the habits you form to support a healthy metabolism [7].
Sleep quality: Getting enough high-quality sleep is crucial to maintaining metabolic homeostasis [8]. If your sleep continually suffers (you sleep fewer than seven hours a night or have an inconsistent sleep schedule), your metabolism may suffer as well — leading to lethargy, weight gain, and other symptoms.
Stress levels: Chronic stress increases levels of cortisol and insulin in the body, and can increase your appetite for sugary foods [9]. This can reduce energy expenditure and disrupt a healthy metabolism.
Chronic dieting or under-eating: Dieting can help you lose weight, but when you are eating less than your BMR requires, constantly yo-yo dieting, or stuck in an extreme calorie deficit, you can do real damage to your metabolism [10]. These extreme, restrictive practices make your body think it is starving, and your metabolism will slow down to conserve energy [11]. This may lead to retaining fat and losing muscle mass.

How Does Metabolism Affect Weight Loss?

Metabolism plays a role in weight loss, but it isn’t the only factor that influences weight loss. Boosting your BMR can be a factor in supporting healthy weight loss, but it’s also important to note that BMR isn’t everything. In fact, obese individuals tend to have a higher BMR than healthy weight individuals, because it requires more energy to support a larger body [12]. The same is true of calories burned. A person who weighs 100 lbs will burn far fewer calories than a person who weighs 300 lbs if both of them jog at the same pace for 30 minutes. This is because of the energy it requires for their body weight to do the work of jogging.

However, it’s worth noting that if you are trying to lose weight, increasing your BMR through dietary choices, improved rest, reduced stress, and increased muscle mass can help to support and sustain weight loss.

How to Support and Improve Metabolic Function

So, how exactly can you improve your metabolism? There are several ways to improve your metabolic function — and overall health — for better body composition, reduced weight, and increased longevity.

Strength training: Lifting weights is well-studied and helps to build and preserve lean muscle, which burns more calories at rest. Incorporate strength training into your routine 2-3x a week, hitting all the major muscle groups [13].
Protein intake: Eating good sources of lean protein, like poultry, fish, soy, and tempeh, supports the maintenance of muscle, keeps you feeling satiated and has a higher thermic effect of food, so your body works harder (burns more calories) to digest it, all while taking in fewer calories. This can help you lose weight more sustainably, without needing a strict or aggressive dieting program.
Daily movement and exercise: Daily exercise, along with increased activity thermogenesis, helps you burn more calories throughout the day, which supports a healthy body weight. Aim to get 30 minutes of moderate intensity activity a day, and take any opportunity you can for more movement – like walking instead of driving, or taking the stairs instead of the elevator. Every little bit adds up, so a short workout or walk is better than nothing.
Sleep hygiene: Getting good sleep is essential for metabolism. Practice good sleep hygiene by sleeping in a cool, dark room and having a consistent bedtime and wake time. Aim to get 7-9 hours per night.
Stress management: Chronic stress elevates cortisol, which can impact metabolism. Practice stress management by trying deep breathing exercises for acute stress, taking walks in nature, and seeking out soothing behaviors, like gentle yoga, reading, or talking with a friend [14, 15]. All of these habits can reduce stress and support metabolism.
Balanced, consistent eating: When it comes to metabolism, extremes are never good. Crash diets and severe restrictions will hurt your metabolism (and weight loss efforts) more than they will help. Try to eat balanced meals that consist of whole foods to ensure you are nourished, satiated, and supporting your weight loss efforts.

Supplementation to Increase Metabolism

Like most things pertaining to health and wellbeing, there is no silver bullet. Supplements are the same way. They can be a great resource for supporting your efforts for improved metabolism and overall wellness, but they are not a quick fix.

That said, to get the most out of your supplements, look for supplements that have been clinically studied to support your goals. For example, ingredients like Berbevis®, ALA, taurine, and Siliphos® – all of which are included in Motus, Tonum’s proprietary weight loss supplement – are clinically proven to support weight loss, maintain muscle mass, and keep your metabolism running smoothly.

Supplementation with Motus, along with healthy habits, like strength training, sleep hygiene, and eating whole foods, can support your metabolism and help you reach a healthy weight.

Takeaways

Metabolism may seem complex, but we’re here to help you remember the key points of supporting and improving a healthy metabolism for a healthy life.

Metabolism works to conserve energy, not just burn calories. Metabolism is the body’s process of converting food into usable energy (ATP) for everything from breathing to moving to repairing cells — not just how fast you burn calories. Shift your focus from "speeding up" metabolism to supporting it through healthy, sustainable habits like balanced nutrition, regular movement, and recovery.
Anabolism and catabolism can be supported through proper nutrition and activity. Healthy metabolism balances anabolism (building and repairing tissues) and catabolism (breaking down molecules for energy). Prioritize a diet rich in protein, healthy fats, and complex carbs, combined with strength training and active recovery (like walking or yoga) to support these dual processes.
Muscle mass is critical for a higher basal metabolic rate (BMR). BMR is the energy your body needs at rest, and building lean muscle directly increases BMR, helping you burn more energy even when inactive. Strength train at least 2–3 times a week, focusing on progressive overload (gradually increasing weight or reps) to build and maintain muscle.
Daily movement is a powerful but overlooked metabolic booster. Non-exercise activity thermogenesis (NEAT) — like walking, cleaning, and fidgeting — can significantly increase daily energy burn without formal workouts. Find ways to move more in your everyday life: take walking meetings, use stairs instead of elevators, pace during phone calls, or do short stretching breaks.
Metabolism is influenced by sleep, stress, hormones, and age — not just diet and exercise. Factors like sleep deprivation, chronic stress, and hormonal imbalances (thyroid, cortisol, insulin) can slow metabolism, while healthy habits help counter natural declines with aging. Aim for 7–9 hours of quality sleep nightly, create a consistent sleep schedule, and practice daily stress-reducing activities like meditation and deep breathing.
Supplements can support, but not replace, healthy habits. Ingredients like berberine, ALA, taurine, and Siliphos® may help support metabolism, but they work best when paired with strength training, stress management, and nutrient-dense eating.

References:

Emily Johnson, MS, RD, is a health editor and writer with expertise in research, metabolic health, and glucose management. She has written and edited for several health tech companies, including Tonum, Veri, Oura, Doximity, and InsideTracker. When she is not writing for Tonum, she can be found reading novels, writing her newsletter, traveling, or getting some exercise with her rescue dog, Ponyboy.

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