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6 Ways to Boost a Slow Metabolism

Written by Dr. Michael Ruscio, DC on July 23, 2025

Written by Dr. Michael Ruscio, DC on July 23, 2025 — Reviewed by Hannah Wright

• What Is Metabolism?|
• What Slows It Down?|
• How to Speed It Up|

Some people seem to eat whatever they want—like pizza, burgers, and ice cream—and still stay lean. It’s easy to assume they just have a fast metabolism, while the rest of us are stuck with slow ones. But that’s not necessarily the case. 

It’s time to stop blaming weight gain solely on a slow metabolism. Gaining weight is usually more complex than just how fast your body burns calories or eating too much. Things like thyroid problems, stress, toxins, and gut health can all play a role.

This article looks at those factors and more—and offers a new way to think about boosting your metabolism, improving your energy, and losing weight.

What Is Metabolism and How Does Your Body Make Energy?

When we talk about metabolism, what we’re really talking about is how well our cells produce energy. Most of that energy comes from mitochondria—the tiny structures inside our cells that convert nutrients (mainly glucose) from food into ATP, the usable energy our bodies run on. 

Each cell has hundreds to thousands of these mitochondria, and their function is affected by many things, including our diet, hormones, stress, and exposure to toxins. That’s why metabolism is far more complex than just “calories in, calories out.”

Although overeating can lead to weight gain by giving the body more nutrients than it needs, it doesn’t affect everyone in the same way 1. In fact, research shows that having a slow metabolism doesn’t always mean you’ll gain weight, and having a fast metabolism doesn’t guarantee weight loss 2. Eating too little can also backfire—your body may respond by holding onto fat, storing it as a survival mechanism when it senses a lack of food.

And being thin isn’t automatically a sign of a healthy metabolism. Some people who appear lean may actually have too much body fat compared to lean muscle, which can slow the metabolism and increase the risk of conditions like diabetes and heart disease 3. 

What Slows Down Your Metabolic Rate?

Your metabolism isn’t just about how many calories you eat or how much you exercise. Those do matter, but many other factors can slow down your metabolism, making it harder to maintain a healthy weight or energy level. Research highlights the following contributors to a slower metabolism 3 4 5:

• Poor diet—especially too many carbs and not enough protein
• Undereating
• Chronic stress
• Infections
• Exposure to toxins
• Imbalances in the gut microbiome
• Poor thyroid function
• Hormone changes or imbalances, like those related to menopause
• Blood sugar swings and insulin resistance
• Lack of physical activity
• Aging
• Genetics
• Ongoing health conditions
• Certain medications, including steroids, antidepressants, and blood pressure drugs

What we can’t control: Our genes and the fact that we’re all aging. Everyone gets older, and we’re all born with a specific set of genes. Some people also need certain medications just to function day to day. These are facts we can’t change, so it’s not helpful to dwell on them when trying to improve metabolism.

That said, we can influence how some of our genes behave. Although you can’t remove genes you don’t like, many lifestyle and diet changes can affect whether certain genes get switched on or off. So even if you’re genetically predisposed to a slower metabolism, there’s still a lot you can do to support better metabolic function.

What we can control: Diet, stress, toxins, gut health, and more. One major but often overlooked factor is chronic stress. Short-term stress (like during exercise or a challenge) can be good, but long-term, chronic stress raises cortisol, which can damage your mitochondria and slow down your metabolism. 

Chronic stress is also one of the most underestimated causes of belly fat. When the body feels under threat, it stores fat around the abdomen to protect vital organs 6 7. 

Chronic infections and toxic overload are other hidden causes of a sluggish metabolism 8 9. These issues affect both your gut and your mitochondria. If your gut is overwhelmed with toxins or harmful microbes, it won’t break down food efficiently, which means your body has less usable energy. A damaged or leaky gut can also let toxins into the bloodstream, where they damage mitochondria and further reduce energy production. 

Supporting both gut health and mitochondrial health is key to restoring a healthy metabolism. 

Slow Metabolism and Hypothyroidism

What feels like a slow metabolism might actually be an underactive thyroid (hypothyroidism). The thyroid gland produces hormones that are well-known for controlling metabolism—people with an underactive thyroid gland tend to have a lower metabolic rate 10. 

Hypothyroidism is a fairly common issue, and people with it often find it hard to lose weight even if they exercise regularly. When I have clients with hypothyroidism, the first step is to support the thyroid—because until it’s functioning properly, other efforts like strength training may not be very effective. 

If you’d like to get your thyroid checked and work with a practitioner to address it, you can schedule a free consultation with the Ruscio Institute for Functional Health. Or, if you want to learn more first, you can check out our online thyroid course. 

How to Calculate Your Resting Metabolic Rate (RMR)

Understanding why your metabolism is slow is the first step to fixing it. But how can you tell if your metabolism is actually underperforming? One easy way is to calculate your Resting Metabolic Rate (RMR)—the number of calories your body burns each day just to keep you alive, without factoring in exercise or other activity 11. This gives you a baseline for how much energy your body needs at rest and can help you figure out if you’re eating too little or too much for your actual needs.

In some cases, people find they’re not eating enough to meet their RMR, which can actually stall weight loss. When calorie intake drops too low, your body responds by slowing your metabolism to conserve energy and protect against starvation. But to burn fat and maintain muscle, your body needs fuel to work with. 

Though it may seem counterintuitive, without enough calories, weight loss becomes very difficult. Other signs your body is in this low-energy state include feeling cold, depressed, and constipated 12.

Knowing your RMR and your Total Daily Energy Expenditure (TDEE)—which includes calories burned through movement and exercise—can also help you fine-tune your diet. It can guide you in choosing the right balance of protein, fat, and carbohydrates for your energy needs. You can use this online RMR and TDEE calculator to get started. 

Once you know how much energy your body actually needs, a short bout of calorie counting can help you see whether you’re generally eating too little (which can slow your metabolism) or too much (which can lead to weight gain). 

But RMR is just the starting point. From there, you can begin making changes that help your metabolism work more efficiently and support long-term energy and weight balance.

6 Ways to Boost Your Metabolism

There are several effective ways to boost your metabolism. Building more lean muscle through strength training and eating foods that support metabolic health can help raise your RMR, making your body better at burning calories all day long.

As long as you’re also addressing deeper issues like low thyroid function or chronic infections, here are some of the most effective strategies for improving a sluggish metabolism.

1. Increase Exercise, Especially Resistance Training

Exercise matters, but the main goal should be to build lean muscle. Lean muscle burns up to 13 times more calories than fat 3.

Research shows that resistance training about three times a week can increase your metabolism by around 96 calories per day—if you’re replacing fat with the same amount of muscle. Aerobic exercise doesn’t have this effect, even when combined with resistance training or a better diet 13.

That doesn’t mean you should skip aerobic exercise. But if you want to boost your metabolism, building muscle should come first. 

2. Get Enough Sleep

Poor-quality sleep and irregular sleep patterns may harm your metabolism in several important ways, including:

• Disrupting hormones that control hunger and fullness, which can lead to overeating 14
• Affecting how your body processes sugar, increasing the risk of insulin resistance and type 2 diabetes 15
• Raising the risk of obesity, especially in children, due to changes in metabolism and behavior 14 
• Throwing off your body’s internal clock, making metabolic health worse 15 
• Negatively impacting digestion and overall nourishment 16

The good news is that getting enough sleep is largely within your control and can help improve your metabolism. 

3. Stay Hydrated

Water is essential for almost every function in your body, including how well you burn calories. When the body doesn’t get enough clean water over time, it adjusts by making more water internally through metabolism, which prompts you to eat more and use more energy in inefficient ways. This can also cause higher levels of inflammation and blood clotting markers, faster loss of muscle coordination, kidney damage, and scarring in the heart 17. 

Here are simple ways to stay hydrated:

• Start your morning with water. Drink a glass before your coffee to rehydrate after sleeping.
• Aim to drink at least 64 ounces (about 8 cups) of water daily. You’ll need more if you’re active or in hot weather.
• Eat foods with high water content, like cucumbers, watermelon, oranges, and celery, to naturally increase your fluid intake.
• Support your electrolytes by adding a pinch of sea salt or a squeeze of lemon if you sweat a lot or exercise regularly.

4. Limit Stress

Chronic stress has been consistently linked to metabolic problems like weight gain, poor blood sugar control, high cholesterol, and increased risk of type 2 diabetes 18. Studies show that stress not only disrupts key hormones like cortisol but also causes inflammation and other changes that can harm metabolism and raise the risk of metabolic syndrome 19. 

Here are some proven ways to manage stress and thereby support your metabolism:

• Mindfulness meditation 20—Spending a few minutes each day focusing on your breath can reduce stress and cortisol levels. If your mind wanders, simply bring your attention back to your breath—this helps build emotional resilience over time.
• Yoga 21—Practicing yoga for even 20 minutes a day can help release physical tension and activate your body’s relaxation response. Poses like downward dog and child’s pose are especially helpful.
• Deep breathing exercises 22—Techniques like the 4-7-8 method (inhale for 4 seconds, hold for 7, exhale for 8) can calm your nervous system and lower cortisol. Just 5 minutes a day can make a difference.
• Time in nature 23—Spending time in nature—or even just looking at images of it—can reduce stress, anxiety, and depression.

5. Increase Your Protein Intake

Eating a diet where at least 20–45% of your calories come from protein can help improve weight loss, fat loss, blood pressure, some cholesterol markers, and insulin levels compared to lower-protein diets 24. 

The current protein RDA (0.8–1 gram per kilogram of body weight) is just the bare minimum to prevent deficiency—not enough for most people to support good health, fitness, or aging 25. Experts from the International Protein Board recommend these higher intakes: 

• 1.1–1.4 grams per kg (2.2 lbs) of body weight for general wellness
• 1.4–1.8 grams per kg for fitness and healthy aging
• 1.8–2.2 grams per kg for building muscle and athletic performance

For a 150-pound person, that means aiming for 75–150 grams of protein per day. 

Spreading this out—like starting the day with a 30g protein breakfast—can help meet your daily needs and support your metabolism throughout the day.

6. Improve Gut Health

Though there isn’t enough solid scientific evidence to say for sure that gut health treatments directly improve human energy metabolism, it’s reasonable to think that poor nutrient absorption can get in the way of how your body makes and uses energy 26. We also know the gut microbiome plays a role in energy use, but there’s no consistent, proven way to change it for a better metabolism yet 27. 

That said, a healthy gut supports overall health. If your gut is out of balance or dealing with chronic infections, it could absolutely be dragging down your energy levels. If you suspect gut issues are part of why you’re feeling tired or struggling to lose weight, it’s worth addressing your gut health alongside good diet and lifestyle habits.

Gut conditions that may interfere with nutrient absorption and metabolism include:

• IBS (irritable bowel syndrome)
• SIBO (small intestinal bacterial overgrowth)
• IBD (inflammatory bowel disease)
• Autoimmune gastritis
• Chronic constipation

For many people, probiotics are a good first step to support gut function and help the body better digest and absorb nutrients. We typically have clients take probiotics while they improve their diet.

Find What Works for Your Body’s Metabolism 

If you’ve been told that a slow metabolism is why you feel tired or struggle to lose weight, that may be only part of the picture. Things like thyroid function, gut health, stress, and toxin exposure can all have a big impact on how your body makes and uses energy. 

Simply exercising more and eating less might not be enough—you may need to dig deeper into issues like your gut microbiome, stress levels, and other personal health factors to truly support your metabolism.

If you’re interested in working with a health coach to improve your metabolism and feel energized again, reach out to us at the Ruscio Institute for Functional Health.

The Ruscio Institute has developed a range of high-quality formulations to help our clients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you. The information on DrRuscio.com is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.