It's often heard: “I have a slow metabolism.” But what does that really mean?
Metabolism - also known as your body’s metabolic rate - refers to all the processes in your body that create and use energy. Think of breathing, blood circulation, digestion, cell repair, and of course, movement.

A major part of this is your resting metabolic rate (RMR): the amount of energy your body burns when you’re doing nothing at all. Even at rest, your body is hard at work - your heart keeps beating, your brain uses energy, and your muscles constantly consume fuel.

How active your metabolism is determines a large part of how much energy you burn each day - and why some people stay at a stable weight more easily than others.

How does your metabolism change as you age?

Your metabolism doesn’t stay the same throughout your life. From around age 35, your muscle mass gradually starts to decline if you don’t actively maintain it. This has a major impact: muscle tissue is metabolically active, meaning it burns more energy than fat mass. Less muscle = lower daily energy expenditure.

Hormonal changes also play a role. The production of testosterone, estrogen, and growth hormone decreases with age, which affects muscle maintenance and fat storage. We also tend to move less as we get older, further contributing to a slower metabolism.

Fortunately, this is not an irreversible process. Research shows that an active lifestyle and regular strength training can slow down or even reverse this natural decline.

Other factors that influence your metabolism

Age is only one piece of the puzzle. These factors also contribute:

When is your metabolism fast, slow, or normal?

There is no universal reference that defines a “slow metabolism.” It always depends on your age, weight, sex, and muscle mass.

However, signs that may indicate a slower metabolism include:

If you experience several of these symptoms, it’s wise to rule out medical causes (like thyroid issues) with your doctor first. If there are no medical concerns, you can safely and effectively support your metabolism and increase your energy levels.

Can you improve your metabolism?

Absolutely—and the best part is: you don’t need miracle supplements. The key is focusing on four pillars: building muscle, optimizing nutrition, increasing daily activity, and improving sleep and stress management.


1. Strength training as a metabolic engine

Strength training is the most effective way to sustainably improve your metabolism. Every kilogram of muscle you build increases your resting metabolic rate. This means you burn more energy 24/7—even while sitting on the couch.
Research shows that resistance training increases muscle mass and fat oxidation, even in adults at older ages.

Start with 2 to 3 sessions per week using basic movements (squat, deadlift, push, row). Gradually increase weights or repetitions.


2. Eat enough—with a focus on protein

Many people eat too little—especially when trying to lose weight. That seems logical, but too large a deficit can slow your metabolism. When your body receives too little energy over time, it shifts into “conservation mode,” lowering energy expenditure. It can also increase stress hormones like cortisol. Excess cortisol promotes muscle breakdown and fat storage, further lowering metabolism.

That’s why it’s essential to consume enough calories, including adequate protein and micronutrients. Protein is crucial for muscle repair and growth, helping maintain your resting metabolic rate. As a guideline: 1.2 to 1.8 grams of protein per kilogram of body weight per day, depending on age, activity level, and training intensity. Examples include: low-fat yogurt, eggs, fish, chicken, tofu, or legumes.

In short: sufficient, high-quality nutrition protects your metabolism, keeps your muscles strong, and helps you stay energized—even during healthy fat loss.


3. Move more throughout the day

Besides structured exercise, daily movement—your NEAT (non-exercise activity thermogenesis)—also counts. These are all small movements throughout the day: walking, cycling, taking the stairs, household tasks, or simply staying active. All of these significantly increase your total energy expenditure.

Research shows:

Practical tip: build short activity moments into your day - take the stairs, walk after lunch, or have a standing phone call. Every bit helps and naturally stimulates your metabolism.

4. Sleep and stress

Sleep is one of the most underestimated factors for a healthy metabolism. A lack of sleep reduces production of key hormones such as growth hormone and testosterone, which are essential for muscle recovery and building. At the same time, it increases cortisol, a stress hormone that promotes muscle breakdown and fat storage, especially around the abdomen.

Poor sleep also affects insulin sensitivity and appetite regulation: people who sleep poorly often crave more sugar and high-calorie foods, making weight management more difficult.

Guidelines to improve sleep: aim for 7–9 hours per night, maintain a consistent sleep schedule, and try to go to bed and wake up at the same time daily. Plan moments of rest and relaxation (like a short walk, breathing exercises, or meditation) to reduce stress and cortisol. Avoid bright and blue light before bed (phone/TV), allowing your body to follow its natural sleep rhythm.

Good sleep not only improves energy and recovery but also enhances the effectiveness of your training and nutrition, keeping your metabolism functioning optimally.

A personalized plan for a slow metabolism

Everyone is different. That’s why standard diets or generic workouts rarely work well. A personalized plan helps align your energy needs, goals, and lifestyle.

Step 1: analysis – understanding your body and lifestyle

The first step in a personalized plan is a thorough assessment. This goes beyond what the scale tells you; it provides insight into how your body functions and where improvements can be made.

A typical assessment may include:

With this analysis, you get a complete picture of your starting point, and your coach can tailor training, nutrition, and recovery strategies to your body.

Step 2: personalized nutrition coaching

Together with your coach, you determine what and when you eat, fully tailored to your metabolism, goals, and lifestyle.

Step 3: Personal training

With personal training, you receive a fully customized program tailored to your body, goals, and lifestyle. It’s much more than performing exercises—it’s a structured approach to increasing muscle mass, stimulating your metabolism, and improving overall fitness.

What to expect:

At Physicum, we:

Personal training is not only a way to get stronger, but a complete approach to optimizing your body, metabolism, and energy sustainably.

Step 4: evaluation & adjustment

To ensure progress, we schedule regular evaluations:

This combination of consistent evaluation and ongoing adjustments ensures your program remains aligned with your body, goals, and progress.

Why nutrition coaching and personal training work together

A well-functioning metabolism never results from just one factor; it’s the synergy between nutrition, training, recovery, and lifestyle. That’s why we combine personal training with nutrition coaching at Physicum, allowing every component to work together and reinforce each other.

With this approach, you:

This combination allows you to naturally improve your metabolism and build a stronger, healthier, more energetic body.

Ready to improve your metabolism?

Do you want your energy back, lose weight more easily, and feel better in your own skin? At Physicum, we’re here to help. Take our match test and discover how we can guide you toward your goals.

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